Guide to Structural Timber Construction for house building

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Five inspiring structural timber homes Guide to timber frame Structural insulated panels Oak-frame construction Cross laminated timber Glulam beams A-Z directory

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An excellent way to build

T

imber really is a wonder material for house construction. It has a whole host of advantages over other building materials: it’s sustainable, economical, thermally efficient and can be constructed quickly. In short, it’s an excellent way to build!

With impressive cost efficiencies, as well as environmental credentials, it’s little wonder that timber is becoming the building material of choice for selfbuilders, accounting for a good percentage of the market and as much as 75 per cent in Scotland.

A self build can be rewarding in so many ways, not least financially, and using timber as the main structural component for your new home will put you on a solid footing.

The build time of a two-storey house is reduced by around 30 per cent – erected and watertight in a matter of weeks, with factory prefabrication making for simple on-site assembly.

Timber construction also allows for more accurate budgeting and the finished building is better insulated, reducing your energy bills. It is kinder to the environment too, with the lowest overall carbon footprint of any building material.

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It easily exceeds Building Regulations requirements, with superior thermal efficiency resulting in homes that remain warm in winter and cool in summer.

And then there is the design flexibility, along with guaranteed accuracy, where the structural timber components fit together exactly as designed. Not to mention the emerging new systems which allow for timber to be used in more applications than ever before.

Produced in association with the Structural Timber Association, this guide explores the various aspects of timber construction. Our thanks to STA members who have supported this publication.

Publisher Peter Johns Editorial Address: SelfBuild & Design Magazine, 151 Station Street, Burton-on-Trent, Staffordshire DE14 1BG Tel: 01283 742950 Fax: 01283 742957 www.selfbuildanddesign.com

Member of the Audit Bureau of Circulations Every effort is made to ensure that the material published in Structural Timber Construction is accurate and reliable. However, the publishers can accept no responsibility for claims made by advertisers, manufacturers or contributors. Readers are advised to check out any claims themselves before using them as the basis for any building project. Contributions are welcome but the safe return of unsolicited text or photographs cannot be guaranteed. Copyright for the contents of this guide rests with the publishers and no part of the contents can be reproduced without written permission to do so.

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Contents

21 26

Timber frame 6

Guide to timber frame Fast, energy efficient and convenient, no wonder timber frame is a popular choice with selfbuilders.

12 A hands-on approach

12

After Potton delivered and erected his timber-frame home, Rob Kybird chose to do many of the finishing touches himself.

16 Cottage comforts This classic cottage-style home has all the creature comforts expected of a modern and energy-efficient home.

SIPs 21 An introduction to building with structural insulated panels SIPs form a strong, lightweight structure, requiring no additional frame or skeleton.

So what more do you need to know?

24 Meeting the challenge When farmer Nigel Box wanted to convert part of a barn into a new home that required the steel frame to be retained, Frame Technologies rose to the challenge.

24

26 A view to the future Julie and David Clements wanted their new saltbox-style home in Yorkshire to be eco friendly, energy efficient and easy to manage in their retirement.

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32 Oak frame 29 Guide to oak frame construction This ancient building method is enjoying new popularity by embracing modern building techniques and materials.

32 Oak dream home Derek and Elizabeth Sandeman have no regrets after replacing a tired bungalow with a new oak-framed country cottage.

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Cross-laminated timber 36 Why cross-laminated timber panels are a versatile building component.

Glulam 37 The strong, light alternative to concrete and steel beams.

Directory 38 A guide to relevant STA members.

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You’re in safe hands

O

ff-site manufactured structural timber systems have advanced greatly in recent years, and they can offer genuine cost, programme and performance assurances for selfbuilders, especially when backed by STA Assure.

STA Assure is the largest UK trade association within the structural timber sector and there are a host of reasons why construction professionals and selfbuilders should choose one of its members. The STA's mission is to enhance quality and drive product innovation through technical guidance and research, underpinned by a members' quality standard assessment – the STA Assure Membership and Quality Standards Scheme.

STA Assure is designed to benefit both members and their clients by promoting the differing accreditations and quality standards held by individual STA member companies. This scheme offers reassurances to the construction community that its members meet or even exceed current legislation and regulatory requirements.

The STA has three levels of membership accreditation – Gold, Silver and Bronze – to highlight the different levels of quality procedures, management systems and product performance standards, together with external accreditations held by STA members.

It is not always feasible, possible or necessary for a member to achieve a Gold level membership. Specific quality requirements differ for each type of member and customer activity depending on the nature of a company's business so a Bronze or Silver member may be the most appropriate company for your project.

The STA has a formal agreement with the NHBC that recognises STA Assure Gold members as compliant with Chapter 6.2 of NHBC's assessment processes for timber structures without the need for further review or completing a HB2445 form. STA Assure has also received

formal recognition from other the industry-leading structural warranty and Building Control bodies including: LABC Warranty Premier Guarantee Protek Warranty Build-Zone Warranty Self-Build Zone Warranty ABC+ Warranty A full and comprehensive Customer Guide to STA's membership standards is available online (see below).

WHAT STA MEMBERS OFFER l They have completed a quality standard assessment – the

STA Assure Membership and Quality Standards Scheme. l They operate to the Site Safe scheme, an initiative to

ensure timber construction is both safe and sustainable. l They are familiar with the latest Building Regulations

and legislation, receiving regular updates from the STA. l They have access to dedicated technical support service,

advice notes and technical documents, including a full range of documents in the STA library. l They fully support sustainable construction and quality standards through adherence to a Code of Conduct.

By providing transparency, credibility and accountability, the STA safeguards the interests of end users, enabling them to partner with a reputable firm that will harness the multitude of inherent benefits that structural timber frame offers.

There is a wealth of information on the STA's website, from advice on timber systems to market reports and top building tips, together with an online members enquiry system.

For more information: structuraltimber.co.uk/self-build

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Timber FRAME Fast, energy efficient and convenient, it's little wonder that this is a popular construction method with selfbuilders. imber frame is the most widely used construction method in the developed world and tends to dominate in colder climates. In Scotland, more than 75 per cent of self builds use this method, and around a quarter of new homes in England are timber framed.

Some half-timbered buildings from the 12th century are still in good repair today and a modern timberframed house is fully recognised for lending purposes by banks and building societies. From the outside, it’s often impossible to tell a timber-framed house from a masonry one, because external cladding is unaffected by the choice of internal walls. In a timberframed house, the outer decorative ‘skin’ is finished in the same way as any traditional block house, using bricks, stone, timber cladding or render.

The Structural Timber Association (structuraltimber. co.uk), which represents the timber-frame manufacturing industry, believes that no alternative building material offers the combination of sustainability, renewable, natural, recyclable, and low embodied energy.

T

PANEL TYPES

When people refer modern timber frames, they are usually referring to building using prefabricated panels.

Open-panel systems are structurally engineered panels that form the inside load-bearing leaf of the external wall, comprising studs, rails, sheathing on one face and a breather membrane. Service runs, insulation, windows and doors are then added later on site. The open-panel system is made from treated softwood timber framing, over which a structural sheet material of either ply or OSB board is fixed. Depending on the system, U-values ranging from 0.26 down to 0.15 W/m²K can be achieved.

Closed-panel systems are usually more expensive than open panels, but faster to erect on site. Made from studs, rails and insulation, with sheathings and/or linings on the faces of the panel, closed panels also incorporate a vapour barrier on the warm side of the insulation and a breather membrane on the outer face of the panel.

If desired, closed panels may also include fitted windows and internal service zone battens, for ease of installation and construction. This will require decisions about positioning services at an early stage.

The walls, floors and sometimes even the roofs of these closed-panel systems are then delivered to site ready for erection, resulting in an airtight building envelope.

Closed panels are far heavier to manoeuvre than open panels and will usually need to be craned into position.

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GUIDE TO TIMBER FRAME

Popular in Scandinavia, this method has been adopted by some suppliers in the UK, ensuring faster build times and less reliance on good weather conditions.

These solutions have been designed to deliver excellent thermal and airtightness properties and are ideal as the basis of a modern energy-efficient home. U-values from 0.25 right down to 0.10 W/m²K can be achieved.

TIMBER FRAME DESIGNS

When it comes to design a timber-frame house is quite different to a masonry one and the structural calculations are usually carried out in-house by the manufacturer.

A timber-frame design is precisely engineered, which means that a timber engineer will need to prove that the structure can bear the imposed loads.

Although most timber frame manufacturers will offer a portfolio of standard designs, which may be adapted to suit individual tastes and requirements, they are also able to produce one-off bespoke houses or to work with plans from an independent architect or other designer.

The package deal is one of the highly seductive elements of buying a timber-framed home, and manufacturers can provide various levels of service depending on your location – offering anything from the design and assembly of the frame right through to a complete turnkey build where virtually everything is undertaken by the supplier's team, delivering a fully finished house.

GREEN APPROACH Timber-frame construction is seen as eco friendly, because wood is a renewable resource, while precision engineering keeps waste to a minimum.

This is in addition to the good energy performance due to the airtight structure and high levels of insulation.

HOW THEY ARE MADE

Unlike a masonry wall, which is built one brick or block at a time, timber panels are lightweight and easy to manufacture and the system lends itself to being prefabricated offsite. Factory fabrication ensures precision timber engineering under controlled conditions, with individual lengths of timber cut to size and pressure-treated with preservative prior to being assembled into the various components, ready for delivery to site.

Almost all wood in UK timber-frame construction is sourced from well-managed European forests, and benefits to the environment include the fact that wood is effectively a carbon-neutral material – even allowing for transport – as living trees absorb carbon dioxide and produce oxygen.

Factory-manufactured timber frames guarantee high levels of accuracy and quality, significantly simplifying on-site construction, which can often take just a few weeks.

During the lead times of around eight to 12 weeks between ordering the frame to delivery, the groundworks can be completed, so it won't impact on the length of the build.

In addition to manufacturing internal partitions, roof trusses and floor and ceiling joists, suppliers are often able to provide doors, windows, staircases, and other joinery as part of the overall package, but make sure you study the small print carefully to be certain about exactly what is being provided in your quote. Frame manufacturers will usually require a deposit and pre-payment for the frame – sometimes for the entire amount.

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VERSATILE TIMBER FRAME The zinc and slate bring a striking modernity to the simple shed-like form of Downview Farm,near Belfast. The architect advocated a timber-frame core as the most effective way of achieving the definition and shape . Timber frame was always going to be the clever choice for the exposed site.

The temperature inside remains comfortable despite the large aspects of glazing.

Timber-frame supplier Kudos worked with the architect throughout to achieve a high level of finish, proving that clean lines don’t just happen by chance.

ON-SITE INSTALLERS Putting up a timber frame is best handled by the experts and preferably someone already familiar with the chosen system. Most kits are sold on a supply-and-fix basis, and a major benefit is that both kit and labour are zero-rated for VAT. Timber-frame suppliers usually insist that their own people, or a builder recommended by them, erect the frame, and to do otherwise may affect the warranty. Some of the larger manufacturers have teams on their permanent staff, but most employ subcontractors as they are needed.

STA represents more than 700 members supplying quality structural timber systems. Under their audited STA Assure scheme, manufacturing members can only use STA accredited erectors (structuraltimber.co.uk/ professional-development/timber-frame-competencyaward-scheme-for-timber-frame-erectors).

THE BUILD PROCESS One of the main benefits of building with timber frame is reputedly the fast build speed which, it is claimed, can be as much as 30 per cent faster than traditional masonry construction times using standard format blocks.

Frames arrive in panel form and can be stored easily, and with less risk of damage, resulting in reduced handling of materials. Also, as structural elements are factory engineered, there’s less need to keep excess materials on site, which reduces waste and potential loss through theft, resulting in a tidier, safer site.

Factory-made frames can be difficult to modify once complete and need to be perfectly aligned with the ground-

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floor slab. Like their masonry counterparts, timberframe construction requires accurate, level slabs and foundations are best left to experienced groundworkers.

During construction, the frame is usually built up storey by storey and exterior wall panels are nailed together. All other components are added on site once the weatherproof shell has been erected and the exterior of the building may be finished using bricks, stone, timber or rendered blockwork.

Once the foundations are complete, the panels can be assembled on site, the roof put in place, sheathed and battened, and finally windows and external doors fitted into their openings if these are not already in place. A kit can take anything from just a few days to several weeks to erect, depending on its size, the site and weather conditions.

INTERIORS With the walls and roof finished in waterproof membrane and left watertight by the erection crew, internal trades can start work quickly. In most cases, the internal dividing walls of a timber-frame house are stud partitions, insulated and finished in plasterboard, with no internal loadbearing walls, the floorplan may be open plan and may be reconfigured relatively easily in future.

As the entire inside of the house is formed by a wooden frame, the installation of internal services is very straightforward, with fewer ‘wet’ trades involved. Careful detailing in timber-frame houses can reduce the impact of airborne sound transmission and there are numerous acoustic insulations on the market, as well as heavier wall linings, which will give impressive results – although the additional cost of materials should be taken into

GUIDE TO TIMBER FRAME

CLASSIC COTTAGE STYLE Selfbuilder Rob Kybird achieved a classic cottage look for his new timber-frame home in Nottinghamshire. Potton supplied and erected the frame, whlle Rob completed much of the finishing work himself (see page 12).

consideration when making your budget calculations.

As timber frames are largely hollow, it is relatively easy to insulate them to a high standard while maintaining a clear cavity between the frame and the external walling material. A timber-frame house, by its very nature, has less mass than a pure block home and will therefore heat up and cool down more quickly – making it prone to fluctuations in temperature. Heat retention will therefore be a major consideration. Timber is a naturally insulating material, however, and technology has developed so that properties can be designed which require no space heating systems at all – eliminating heating bills.

An increasing number of selfbuilders want to build ultra low-energy homes that perform well above the levels required by current Building Regulations. Unlike masonry houses where there is limited capacity for cavity insulation, timber-frame homes can have thicker wall sections to accommodate more insulation between the studs.

COSTS AND MORTGAGES Timber frame is often perceived as being more expensive than traditional masonry construction, but any additional outlay should be recovered thanks to the time savings.

Project costs are reduced not because timber frame is cheap, but because factory fabrication allows for greater predictability and a faster pace.

One of the main factors to consider before going down the timber-frame route is cash flow, as manufacturers will usually require pre-payment for the frame. Selfbuilders are always taught never to pay for anything up front, but in this instance, it may be unavoidable and there are mortgages available which take this into account.

Fortunately the days of timber frame being considered too risky for lenders are well behind us. Mortgage providers recognise the reliability and quality of this form of construction. A house which can be erected quickly and made weathertight in a matter of weeks, reduces the risk of costly budget over-runs due to delays caused by inclement weather.

WHY CHOOSE TIMBER FRAME? It’s eco friendly Timber is not only a ‘green’ material, its high thermal insulation means that a timber-framed house is energy efficient, with low heating bills and a low carbon footprint.

It’s light Timber frame is a light construction method compared with masonry and therefore requires comparatively less expensive foundations. It also enables larger buildings to be constructed on difficult sites.

It doesn’t need good weather The structural weatherproof shell can be erected quickly, allowing the internal fit-out team to carry on regardless of the weather. With less dependence on the weather, site planning is more predictable. Other trades can also begin work before the outer brickwork is completed.

It needs less drying-out time Internal finishing can be completed sooner with less risk of shrinkage cracks.

Factory quality Prefabrication ensures the quality is consistent and accurate. The precision-engineered units are made in the factory, before being assembled on site, so there is less dependence on the skills of on-site contractors.

Less wastage and theft Because the structural materials are all quantified in the factory there is less wastage. The size also makes theft of materials less likely.

Accuracy Precision engineering means that all walls are vertical and flat, and rooms are true and square, making decorating and installing carpets and fitted furniture easier.

It’s easy to store on site The kits are delivered with the sections labelled, so materials can be unloaded and stored in the correct order for erection.

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Never a better time to consider timber frame Rising energy costs – along with Net Zero Targets – have made it essential to consider timber frame construction, argues Frame Technologies MD Simon Orrells.

It’s been impossible to escape the news of increasing gas prices. Rising energy rates have resulted in a cost-of-living crisis unlike anything seen before. This, alongside growing concerns over carbon emissions, has meant that more and more people are evaluating their individual impact and choosing greener ways to live.

Building energy-efficient homes is one of the crucial steps to reaching zero carbon and keeping bills low. As a provider of bespoke timber systems, I’ve long been championing sustainability in the building industry, simply by choosing the right material – timber.

Timber frame is the UK’s fastest growing construction method, and a popular route to achieving energy-efficient and environmentally conscious homes. Timber is the only organic, non-toxic, naturally renewable building material, offering design flexibility, quality and speed of build, as well as achieving excellent thermal performance.

Timber is significantly better for the environment than other building materials. Not only are more trees planted than are felled (a net increase so more carbon can be absorbed), but the embodied energy costs are considerably less than those in other forms of construction.

Energy use in homes accounts for around 14 per cent of UK greenhouse gas emissions and this is something that can easily be addressed, especially when it is considered at the initial design stage. Using timber with a fabric-first approach is one of the most cost-effective routes to reducing your carbon emissions. Timber frame delivers the most airtight and energy-efficient envelope of any building material.

As well as ticking the environmental box, high levels of insulation within the timber frame mean that these homes are extremely economic to run. A well-insulated timberframed building needs less energy to heat it, which means long-term savings.

Choosing renewable energy sources for your electricity and heating is also a great way to make your home greener. However, renewable energy sources can only excel when the building envelope is efficient. Solar panels, heat pumps and biomass boilers should all be considered – but if the building isn’t airtight, these products won’t run effectively.

There has never been a more important time to build sustainably – both for the planet and for the pocket. I see a responsibility in championing and encouraging the use of timber frame, not only due to its reduction of embodied carbon in the built environment, but also because it’s building to best value and long-term energy investment.

More people are realising that it’s not only more energy efficient but also more cost efficient to build a sustainable home than it is to buy a house that is built to cost but costs the earth to heat – literally and figuratively. People are building with a conscience, and they’re also safeguarding their future; choosing to keep their outgoings smaller later in life and avoiding the risk of fuel poverty.

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TOP TIPS FOR SELFBUILDERS

Stick-build versus prefabrication It may be tempting to see whether a local joiner can ‘stick-build’ your home for less than the price quoted by a recognised manufacturer, but remember that one of the main benefits of a timber frame is its off-site manufacture. Prefabrication allows for controlled, precision engineering, so the frame is produced to exacting standards and in line with quality assurance procedures. It will also be designed and manufactured for speed of erection. In contrast, a carpenter is unlikely to have a quality assurance scheme in place; ultimately, it will be their individual skills and their commitment that will determine the quality of the build and timescales. Bear in mind that delays will have a knock-on effect and could mean additional costs.

Low running costs High levels of thermal insulation are relatively easy to achieve with a timber frame, mainly because the core insulation layer is housed within the structure. In addition, multiple layers of insulation can be added to the structural fabric to increase thermal performance. Most timber-frame companies will offer a range of U-value options. The better ones will be happy to create a panel to meet your specific U-value requirements.

Consider in-house design services Wood is light and strong. It’s a highly versatile building material that lends itself to innovative design and stunning architecture, so a Grand Designs-style, architect-designed house is not a problem for timber frame. But if you’re planning to build a typical family home, you can save money by choosing a manufacturer with an in-house design service. Some offer standard design packages while others can help you design your dream home for a fraction of the cost of an architect.

Some in-house design services will even work out free should you proceed with a timber-frame kit order. This can save up to 12 per cent of your total build cost.

Speed can deliver dividends A timber-frame kit can be manufactured concurrently rather than sequentially, enabling it to be delivered to site ‘just in time’ upon completion of site foundations. With just a couple of weeks required to erect the house to the wind and watertight stage, you’ll have more control over your build schedule allowing you to factor in follow-on trades soon thereafter. A reduced construction programme also has the potential to deliver cash-flow benefits if your project is designed to generate income.

Finding a good manufacturer The Structural Timber Association (STA) is the go-to trade association for information on structural timber systems in the UK. Its Quality Assure Scheme can help you chose a timber frame supplier, confident in the knowledge that they will have been subject to a rigorous independent audit process. A list of STA members can be found at: structuraltimber.co.uk

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A hands-on self build Four years in the making, Rob Kybird’s timberframe home has aesthetics at its core, achieved with patience and attention to detail.

R

ob Kybird had dreamed of building his own home for many years and so when, in 2014, he found a half-acre plot in a leafy Nottingham suburb, he knew the time had come to take on the challenge. “Self build appealed to me for many reasons,” explains Rob, who worked in banking until leaving his job to carry out the project. “The freedom of design choice, value for money, and also achieving a better build quality were all important aspects in my decision.”

The L-shaped site has a generous garden with treelined fields beyond, and so maximising the view from the back of the house was a priority. Rob, who has two grown-up children, had been aware of timber-frame housebuilder Potton for 20 years, having come across the show centre by chance. He was immediately drawn to the Gransden, one of Potton’s show homes that is rooted

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EXTERIOR Clad in render and brick with exposed timbers, the house is rooted in tradition with an aesthetic that extends into the classic garden.

“Potton proved a good choice, from original design consultations right through to the completed build.” in tradition and characterised by exposed timber posts and beams, low-hanging eaves and dormer windows.

“The team at Potton proved a good choice, from original design consultations right through to the final completed build SAP calculations,” says Rob. “Their individual, personalised service demonstrates a wealth of construction design expertise, technical knowledge and customer-focused support.”

Rob had his own ideas of what he needed from his five-bedroom home, and so a number of changes were made to the floorplan, redesigning the interior to provide a series of rooms, each space distinct yet connected, with its own character while being part of a harmonious whole. Uniform finishes, such as white limestone tiles and one type of carpet, achieve consistency.

A sunroom extends from the rear facade, with roof lights dropping in daylight which bounces off the white tiled floors and into the inner spaces of the house. The multifaceted sunroom also allows views of the garden and countryside to be visible from the kitchen, where there is a drop ceiling housing a glass extractor above the hob.

Aesthetics were high on Rob’s agenda, which saw illuminating touches such as LED strip lights beneath the 30mm Silestone worktop, providing a sense of drama. German kitchen company Beckermann produced the high-quality handleless kitchen, 3D glass-effect

HOMES OAK-FRAME COTTAGE

LOCATION Noinghamshire LAND COST £390,000 BUILD COST £300,000 (excluding garden) WORTH £820,000 FLOOR AREA: 260 sqm

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acrylic doors and textured concrete-effect doors on the wall cupboards that house the ovens.

Tall, thin, open alcoves provide a connection between the living and dining rooms, exposing a view to the next room on both sides of the feature fireplace.

Exposed timbers are on display both internally and externally, featuring throughout the interior of the house in varying degrees and most celebrated in the master bedroom, which has a number of horizontal and vertical posts and beams. Soaring ceiling heights are twinned with panelled doors, heavy linen curtains and an ornate mirror to add opulence and charm. A sense of space is created in the en suite bathroom by a large inset mirror, which reflects light onto the shower screen and up into the partially vaulted ceiling above.

The large bathrooms are fitted with top-of-therange sanitaryware and tiled in warm yet pale tones punctuated by the richness of the wooden beams, creating a light and relaxing space.

Exposed brickwork in places adds to the rustic appearance of the substantial timbers which have a strong woodgrain. Extra-wide doors further contribute to the sense of opulence of the interiors, leading out from the generous double-height hallway.

Rob managed the project from the outset, breaking ground in the winter, with heavy rain causing

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KITCHEN A German kitchen company supplied the units, island and wall cupboards.

GARDEN ROOM Views to the garden can be enjoyed from the sunroom, which has windows on every face and roof lights above.

delays to the excavation work. The build was to take four years, with Rob taking on many of the bigger jobs himself. “The frame went up in two weeks, which was really exciting to watch,” he recalls.

“Once that was all erected and the block-and-beam floor was laid I took over, installing the plasterboard, insulation, the roof covering, building the garage, laying underfloor heating, doing the second-fix electrics, tiling the bathroom, building the stairs and fitting the kitchen.”

A formal classic garden to the rear includes a path lined with columns supporting a pergola, a raised bed surrounding a fire pit and comprehensive tree planting, much of which Rob did himself.

“I resigned from my job to focus on the build but what I hadn't expected, or intended, was to become quite as comprehensively involved. It surprised me just how much a little bit of confidence and a lot of YouTube tutorials allowed me to become so hands-on and achieve a quality result, if a little slower than a professional.”

INTERIORS The country home has a warm, cosy feel, with lavish finishes and small touches of detail creating an opulent look.

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Cottage comforts This traditional-style country cottage was built using modern methods of construction.

“W

e first became aware of the development by chance when we were out for a drive on a Sunday afternoon,” recalls Kevin Swift of his first sighting of an exclusive housing development in Herefordshire. “We were so impressed with the style of development that we drove onto the site even though we were not considering a move.”

While Kevin and his wife Kate were ‘having a nosy’ around a partly completed cottage, the couple were approached by a man who turned out to be the developer, Les Chambers, who asked if they would like to have a look inside.

“Les explained that the houses were being built using timber-frame construction which provided excellent insulation and would therefore keep heating costs low,” continues Kevin. “He also pointed out that the construction technique made it easy to redesign the floorplan if needed in the future – bedrooms two and three, for example, could be made into one quite easily, if required.”

In the past the Swifts had considered buying a cottage, but were put off because those they had seen tended

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EXTERIOR Externally, the brick-clad timber-frame home has a traditional countrycottage appearance.

to have small windows, making them dark inside, and also because of the potential maintenance costs.

“We could see immediately that this property would give us everything we wanted – a modern house with a cottage design, plenty of light and low maintenance. We also would be living on a small development with close neighbours, which is desirable as you get older,” says Kate.

“Even though the property was still to be completed, having listened to what Les had to say we decided there and then that we wanted to buy it. We made arrangements the next day to put our existing house up for sale." The property sold within two weeks and the Swifts moved into their new home five days before Christmas 2018.

“We have now been in Acorn Cottage for over three years and have absolutely no regrets about the decision we made on that Sunday afternoon,” says Kevin.

“This is the first property we have owned in which the temperature is constant. The lounge and kitchen are probably our favourite rooms, but the cottage character can be found throughout the house.”

During their time at Acorn Cottage, three further houses have been built on the estate, giving the Swifts an insight into the construction process from start to finish. This has confirmed their initial belief that

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INTERIOR Internally, the cottage has all the creature comforts of a modern home, with low running costs, plenty of natural light and comfortable temperatures year round.

THE SPEC ARCHITECT John Phipps Architectural

they have bought into a quality construction.

“We have seen other developments being built, whilst we have travelled around the country, and we can honestly say that we believe none compares with the quality of the timber frame construction provided by Taylor Lane.”

TIMBER FRAME (140mm) Taylor Lane INSULATION 100mm rigid polyurethane JOIST TYPE I-joists TRUSSES Mix of trusses, purlins and rafters

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The STA defines the standards for the use of timber building systems in the UK ■ Self builders choosing and STA member will be backed by a members’ quality standard assessment – the STA Assure Membership and Quality Standards Scheme.

■ Offsite manufactured structural timber systems have advanced greatly in recent years, and they can offer genuine cost, programme and performance assurances for self-builders – especially when backed

by STA Assure.

■ STA Assure reassures customers that our members meet or even exceed current legislation and regulatory requirements.

■ STA Assure is formally recognised by six of the industry leading structural warranty and building control bodies including: LABC Warranty, Premier Guarantee, Protek Warranty, Build-Zone Warranty, Self-Build Zone Warranty and ABC+ Warranty ■ STA members operate to the Site Safe scheme – an initiative to ensure timber construction is both safe and sustainable ■ STA members fully support sustainable construction and quality standards through adherence to our Code of Conduct

By providing transparency, credibility and accountability, the STA safeguards the interests of customers, enabling them to partner with a reputable firm that will harness the multitude of inherent benefits that structural timber frame offers.

There is a wealth of information on the STA’s website, from advice on timber systems to market reports and top building tips together with an online members enquiry system.

For more information go to: www.structuraltimber.co.uk/self-build

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In association with

An introduction to

Building with SIPs WHAT ARE THEY? Better known as SIPs, structural insulated panels are a preengineered building system, which was developed in America in the 1930s and first introduced to the UK in the 70s.

The panels are made up of two parallel faces – usually oriented strand board (OSB) – sandwiching a rigid core of expanded polystyrene or injected urethane.

These are the most common in the UK but other variations of facing materials and cores exist. The stressed skin panel makes it exceptionally strong, and high levels of insulation can be achieved in thinner wall thicknesses than other forms of construction.

SIPs provide a fast, efficient way of building walls, requiring less timber with fewer studs compared with a timber frame. They have very good thermal performance and form a strong, lightweight structure which is fast to erect, thanks to the large components. They cost slightly more than conventional timber frame with insulated walls and uninsulated roof trusses, but the faster build speed, reduced waste, lower labour costs and less need for on-site machinery can offset the extra expense.

Energy-saving benefits should also be considered.

SIPS Manufactured off site, SIPs can be used in a wide range of applications, and are quick and easy to erect, usually with a crane.

APPLICATION SIPs can be used as the inner skin of a cavity wall, as a self-supporting single-skin structural wall, in place of timber frame or blocks, and as a pre-insulated roofing structure. They can be used in walls and roofs, creating ecologically friendly and energy-efficient buildings.

Suitable for new builds and home extensions, SIPs are commonly used for garden buildings and garages, as well as making ideal infill panels for other structures, such as oak, steel or concrete frames.

They are perfectly suited for roofs for new builds, extensions and renovations. The panels arrive pre-cut, with insulation already fitted, and span from wall to ridge beam – usually unsupported. This means that the roof space can be left completely open to be used as further accommodation, storage or as a vaulted ceiling.

SIPs are very flexible and can be used with any external cladding, including brick, render, weatherboarding and aluminium. They can also be roofed with slates, tiles or metal coverings. Internally, the panels may be simply finished with plasterboard and a skim coating (with service cavities where needed) so wet trades

structuraltimber.co.uk / BUILDING WITH TIMBER

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In association with

PICTURES

are kept to a minimum and build times reduced.

A SIPs house is very airtight so it won't require much in the way of heating due to the energy efficiency of the building. SIPs are particularly suited for air source heat pump installations, and mechanical ventilation is strongly recommended.

THE PROCESS House designs can usually be modified to suit a SIPs system. It is sensible to choose a designer who has worked with SIPs and understands the structural implications of a panel system, or use a package company.

Manufactured off site as blank 1.2m-wide panels, with various standardised height options, SIPs panels are cut to size and the openings formed. Designing a house using standard SIPs sizes – usually 1.2m by 2.7m – will be the most cost-effective way to use the system. Utilising a 1.2m grid will reduce the number of cut panels and limit waste, as well as minimise the cost for a fabricator to cut panels to fit.

SIPs can also include service ducting, which makes wiring easy but means that the electrical layout will need to be planned at an early stage. Alternatively, services can be run through internal partition walls, with wiring passing through the cavity between the panel and internal plasterboard, or through a double layer of plasterboard. Including a service zone means that you can decide on the services distribution at a later stage.

Manufactured in the factory the panels will be delivered on site where they can be erected – often by the same company. Some SIPs companies offer a full-build package while others rely on the selfbuilder or project manager to take responsibility for the foundations and fitting-out stages.

Be sure to follow the manufacturer’s recommendations for sealing joints properly. Edge openings, such as window reveals, are lined with inset timber to allow frames to be easily fitted, and floors may be sandwiched between upper and lower walls or attached with joist hangers.

Most foundations are suitable, but the slab should be accurate and leveI, within tolerance, and on-

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SIPs are made in the factory and are relatively easy to handle on site. They can be put in place quickly to achieve a weathertight shell and achieve unrivalled levels of airtightness and insulation.

site access should be available for a suitable crane or telescopic handler if required. Panels are joined together, and window and doors are installed on site.

Lightweight wall cladding like cedar, render, rainscreen and brick slips will require additional support to form ventilation spaces, while finishes such as brickwork and stone will typically require foundations to carry the increased weights.

THE BENEFITS l SIPs offer high levels of insulation, structural strength, and airtightness, with thinner wall sections. They can also increase the available roof space, thanks to their truss-free construction, enabling rooms to be created in the roof. . l By combining the stages of conventional timber-frame construction – framing, sheathing and insulation – into a single unit, a structure can be erected quickly and with less specialised labour. A crew of two, with no special equipment, can easily install smaller panels, while larger panels may be erected with the use of a crane. l SIPs are relatively lightweight, at around 25kg/ sqm, and may only require a reduced foundation specification. The shell of a typical house can be erected within a matter of days. l SIPs don’t require particulary good site conditions (except for wind) and the speed of erection can offer savings on skip hire, scaffolding and finance costs. l The size of the panels makes them less likely to be stolen from site than more conventional building materials. l The panels are exceptionally strong, and high levels of insulation can be achieved in thinner walls than other forms of construction. In timber-framed buildings the spacing of vertical timber wall studs is usually at 600mm centres, whereas with SIPs panels these are usually 1,200mm, depending on point loads. SIPs use insulated splines to provide a continuation of the insulation core.

Choosing deeper panels will increase energy efficiency, and U-values as low as 0.10W/m2K can be achieved. l SIPs are ideal for meeting the stringent energy-efficiency requirements of Passivhaus construction. A Passivhaus build is airtight and has high levels of insulation, with little need for home heating and cooling. l Radiators, kitchen cabinets, light fittings and other fixtures can be easily attached to the continuous OSB surface, with little or no additional support required. l The OSB and insulation core are resistant to attack by mould and microbes and have no food value to vermin. l The jointing techniques in SIPs buildings mean that sound transmittance between rooms is reduced.

6 top SIPs tips Building your own home can be a daunting prospect but to get you started and help you along the way, here are a few pointers from SIPs expert Ian Clay to make sure your self-build experience is a good one.

1: Do your product research You may have already decided to build with SIPs but remember, not all SIPs systems are the same.

There are plenty of systems on the market, so make sure you understand the composition of SIPs and the benefits the different options offer.

at the lifetime cost savings of a thermally efficient SIPs home and, most of all, take comfort from living in a sustainable home that you’ve built yourself.

3: Find a credible supplier

Look at thermal qualities, the jointing system - which is key to creating an airtight envelope – certifications and fire performance, strength and stability. Consider a recognised brand such as the Kingspan TEK Building System for all-round quality.

2: Weigh up the long-term benefits Budget is key with any self build and it’s easy to lose sight of the long-term benefits of SIPs. Consider the speed of construction and short build programme, reduced on-site labour and plant costs, the additional floor space, ie a habitable roof space, and the increased value it brings. Look

Just like the variety of SIPs systems available, there are many suppliers offering different levels of service and product.

Your supplier should demonstrate unrivalled knowledge of their product, offer a comprehensive package of design, supply, installation by certified fitters, and be members of the Structural Timber Association (STA). Ensure they are transparent in their costings and capabilities.

4: See if you can arrange a factory visit After you’ve made your shortlist of suppliers, visit their factories and meet the teams.

You will quickly get a feel for the organisation and see how your new home will be designed and fabricated.

Also, ask to see examples of previous work and speak to past

clients about their experience with the company.

5: Be ambitious with your design There are no limitations to SIPs designs and homes don’t have to be boxy and boring. If you, your architect or SIPs designer has vision then almost anything is possible.

Consider adding value to your project with a ‘room in the roof’ or double your room height by leaving the roof space open to the apex.

6: Plan upfront It’s important to work with your provider on some upfront thinking.

This will ensure that window and door openings are suitably positioned, MVHR duct location is identified to enable correct alignment of floor joists, and any other technical complexities are identified early on.

It’s a lot of work upfront but it will ensure value engineering, precise fabrication and save time, hassle and possibly additional costs later on.

Ian Clay is managing director of SIPS@Clays: clays.com

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In association with

Meeting the

challenge When farmer Nigel Box approached Frame Technologies to convert his barn into a family home, the Herefordshire company was ready to take on the challenge.

F

rame Technologies used an energyefficient timber system to convert a steel-framed agricultural barn and concrete yard into a sensitively integrated residential dwelling. Nestled in an eightacre field for grazing livestock, the stunning new three-bedroom family home is idyllically located in beautiful Herefordshire countryside.

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Planning permission for the barn conversion was approved under Permitted Development Part Q. Frame Technologies has created a modern structure that blends into its agricultural setting.

With any barn conversion, there are specific challenges to consider as working around an existing structure can be tricky, especially as they are not originally intended for human habitation. Most farm buildings are not insulated either, so significant work needs to be done to upgrade their thermal performance.

On the plus side, these structures can offer unique features, such as double-height internal spaces, beautiful open-plan living, and fantastic rural locations, which make them so aesthetically pleasing.

With the Leadon Dale project, farmer Nigel Box used the barn for winter housing of his beef cattle and hay storage.

Initially Nigel was concerned because it looked unlikely that he would get planning permission for an on-site residence. However, under Permitted Development Part Q for change of use of an existing agricultural building to a residential dwelling, planning permission was granted.

Adopting a fabric-first approach to ensure optimum energy efficiency, Frame Technologies created a unique timber solution to the planning requirements which stipulated that the existing steel framework had to remain in situ and the building could not be enlarged.

Using integrated architectural drawings along with Nigel's additional design requests, Frame Technologies has created a structure that blends into its natural surroundings and retains its agricultural heritage, thanks to an innovative timber system and cement timber-effect external cladding.

Careful consideration had to be given to the home entrance to take into account the daily farming and agricultural activities. The new timber dwelling incorporates undercover car parking for protected access to the dwelling, as well as a downstairs shower room at the immediate entrance.

HOMES BARNCONVERSION

THE INTERIORS The new home has a distinctly modern look and offers year-round comfortable temperatures, thanks to the airtight structure, high levels of insulation and solar gain from south-facing glazing.

To improve storage, two custom loft spaces have been built into the roof voids to the left and right of the main living area.

The barn was built using Frame Technologies’ unique Tech Vantage System, consisting of a 140mm panel with glass mineral wool insulation that is tightly packed between a sheathing board and a wood fibre board. Inside the panel, a 25mm service batten is nailed to the OSB. Based on a breathable wall principle, the system uses natural insulation to deliver a wall U-value of 0.14 W/m2K. The system’s excellent thermal properties work well with the impressive solar gain from extensive south-facing glazing.

To reduce cold bridging, the wall is sheathed in 20mm wood fibre board, which is fixed to a 140mm timber stud with full-fill insulation. A 9mm OSB is fitted internally with site-fitted PIR insulation, with tapered joints, a 25mm x 50mm service batten and 15mm plasterboard.

The floors use 254mm top-hung metal web joists, instead of traditional ring beams, to reduce shrinkage and improve thermal performance through the floor zone.

Optimal airtightness has been achieved through a timber system that includes membranes and tapes for sealing joints or apertures around building services; airtightness detailing in critical areas such as

THE BUILD The original steel frame has been retained, with Frame Technologies' Tech Vantage System used to provide an insulated airtight shell.

“When we were obtaining quotations for the timber frame, most companies we approached were put off by the requirement for the steel-framed building to remain in situ.

In contrast, Frame Technologies welcomed the challenge.”

Nigel Box, owner

intermediate floor-to-external-wall panels; battens to form service zones and reduce the need for penetration through the barriers; and OSB sheathing on internal faces of external walls that were then taped.

Following a site measure and survey, it became apparent that the original slanted steel framework of the barn was twisted. Working with Frame Technologies, Nigel uprighted the building based on structural details. The next challenge was to erect the wall panels and integrate the existing steel trusses of the old building with the roof zone of the new frame. This was achieved using an engineered rafter, sheathing and roof sheets that matched the existing design.

The structure was made weathertight within days, and with project planning, efficiency was maximised, on-site risks were minimised and internal works could run parallel to external finishes. Not only is the timber system environmentally friendly, recyclable and waste efficient, it is also lightweight, requiring only simple cost-effective foundations.

structuraltimber.co.uk / BUILDING WITH TIMBER

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In association with

SIPs TEK new home Julie and David Clements wanted their new home in Yorkshire to be eco friendly, energy efficient and easy to manage in their retirement.

“W

e wanted to make the best use of the site to create an attractive and practical family home. Our vision was a saltbox design with a blend of traditional stone, slate and contemporary windows,” explains Julie Clements, describing her new home in NorthYorkhire.

After semi-retiring, Julie and her husband, David, wanted to build a new modern, low-maintenance lifetime home on a 0.6 acre plot in the grounds of their original 1903 stone house. Although downsizing, they didn’t want to downgrade, so with architect Vic Craven from Craven Design, they drew up plans for an energy-efficient SIPs home which was small enough for the couple to manage in retirement, yet flexible enough to welcome family.

Inspired by the traditional saltbox homes of New England, Raikes Corner sits perfectly within the Skipton Conservation Area and complements the traditional stone and slate homes found in the Gateway to the Dales.

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SIPS NEW HOME

As far as possible, the Clements wanted to use local suppliers, materials and trades to reduce the carbon footprint of the build. Fortunately, their SIPs supplier, SIPS@Clays, is less than three miles away, and local recycled stone was used for the cladding.

The three-bedroom home, which achieved an impressive airtightness of 1.5m3/h/m2, was built using the 142mm Kingspan TEK building system.

It is clad with close-jointed traditional stone with a slate roof and has solar panels incorporated into the SIPs roof, an MVHR system, underfloor heating and bespoke triple-glazed Weru windows.

One of the advantages of the 142mm Kingspan TEK system is the option to add an additional layer of internal insulation. David and Julie’s new home has 220mm of dense insulation in the slab, an additional 50mm on the inside of the SIPs panels on all exterior walls, and 100mm on the roof panels. This continuous layer of insulation covers all posts and lintels and, together with minimising the steel used within the structure, substantially reduces cold bridging.

An MVHR system and triple glazing keep

EXTERIOR The saltbox design features single- and double-storey sections, with a large southfacing roof with five Velux roof lights.

The house is constructed using SIPs and the exterior is clad in local stone. The build was completed in just eight months.

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In association with

DOWNSTAIRS

heating to a minimum, which helped the house achieve a SAP rating of A98.

The SIPs roof allows additional internal height in the entrance hall and kitchen, as well as the upstairs bedrooms, and was also key to the saltbox design, with a single-storey, south-facing frontage, double storey to the rear and an asymmetric roof. The large southfacing roof has five Velux windows and 14 in-roof solar panels to generate more electricity than the couple use.

The SIPs roof also minimises the ridge height to 6.9m.

Prefitting the windows in the SIPs made it quick and easy to get the structure weathertight so the build could proceed efficiently. The time-consuming application of the external stone cladding could proceed at the same time as the internal works. The SIPs structure also offered flexibility with some of the internal walls so,

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Large glazed pocket doors can divide the sitting room when required. A playroom for grandchildren also leads off the entrance hall. There is a downstairs en suite bedroom for lifetime living which has large windows with garden views.

Thresholds have been avoided and wider doors throughout allow wheelchair access.

KITCHEN To enhance the kitchen views, picture windows sit flush with the Corian work surfaces. This was achieved with the SIPS@Clays team, Weru and the kitchen designer and contractor Roger Tiffany working closely together.

for example, the walls in the en suite bathrooms were positioned to fit the 1,700mm shower trays and in the main bathroom to best suit the large 900mm tiles.

SIPs also came into their own on the tight site, which has a tricky access from the main road. This would have been a challenge for a traditional build but with the efficient delivery of all the components the superstructure was installed swiftly.

Raikes Corner is an exemplar of the advantages of SIPs construction, taking just eight months to complete what is a stunning new home.

In association with

A guide to

Oak frame construction

T

he time-honoured tradition of oak-frame construction has never really gone out of fashion and is as popular as ever with selfbuilders, thanks to recent energy performance innovations. Period halftimbered black and white houses have long been admired for their beauty and structural integrity, having survived for centuries, with some dating back to mediaeval times.

Building a new oak-framed house offers the perfect compromise – the chance to combine modern building materials with the instant appeal of exposed beams and timbers. Modern technology allows designers to utilise the beauty, strength and integrity of the frame to its full effect, creating open-plan living spaces without the need for internal structural walls.

Oak is a slow-growing wood with a tight grain which makes it durable, strong and a natural insulator. In a fire, a protective layer of charcoal forms around the outside of a beam, delaying damage to the core, and most oak frames are sturdy enough to withstand the ravages of

OAK FRAMES Often lasting more than 200 years, oak is a perfect building material: sustainable, durable and a natural insulator.

a tornado. A lifespan of at least 200 years is achievable for a well-designed oak frame and, even then, there is the chance to continue the tradition of reusing the timber for other purposes when a house has had its day.

Ultimately, oak will biodegrade when eventually redundant, making it the perfect natural building material.

MODERN TECHNOLOGIES While the design and carpentry of oak frames were already highly developed by the mediaeval period, modern technologies such as insulation, glazing and frame infill techniques now far outperform their historic counterparts. Oak’s versatility can be exploited in great open-plan spaces, soaring vaulted ceilings, galleries and atriums, adding to the sense of drama.

If choosing to build in oak it is important to use an architect who is familiar with the method, or at least to consult an oak-frame specialist early on. Traditional oakframe homes are created around a series of rectangles (bays), which make up the base structure (box frame). A good designer will help you to recognise how to make the most of your structure, the best orientation and the size of the bays and spans. They will also work out the loads, as well as the scale and proportion of the rooms. The design will also be affected by roof pitches – between 42.5 and 52.5 degrees – with the most common being 45 degrees.

It is worth noting just how flexible the design services offered by oak frame companies can be. Many selfbuilders assume that they will have to build one of the standard house types shown in their brochures but these tend to be a sales aid designed for guidance rather than an indication

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SIPS NEW HOME

In association with

for an oak frame because these can vary enormously depending on how busy the suppliers are, frame size, design complexity and other issues.

RIDGE

This is a estimating stage set of drawings for discussion only.

PRINCIPAL RAFTER

WIND BRACE

STRUT PURLIN

CONSTRUCTION

WAISTED KING POST COLLAR -

-

Like all timber-frame construction, the foundations must be accurately completed before the frame can be delivered, so ensure you leave plenty of time for unforeseen problems at this stage. Oak frames need a level surface, and poorly built foundations are a frequent problem for all types of timber frame, so it pays to employ experienced groundworkers.

Make sure that site access will not be a problem for a crane, which may be required to lift the huge trusses and cross sections from the lorry. Erecting the frame will then usually take between a few days and several weeks to complete by a specialist team.

Once the frame has been built the timber stud infill panels and insulation can be fixed in place, and the shell clad with materials such as brick, stone, weatherboarding or render.

Structural insulated panels (SIPs) are a modern alternative 190XXX -01 to a timber stud wall, manufactured in a controlled environment and shipped to site ready for erection. They consist of an inner insulating core of expanded polystyrene (EPS) sandwiched between two outer skins of oriented strand board (OSB), and provide excellent thermal efficiency.

Whether renovating or building from scratch, it is recommended that traditional materials are used such as lime mortars and plasters, which allow for minor building movement. Hydraulic lime mortars are particularly useful in timber-frame buildings because their excellent vapour exchange properties minimise rot and damp while providing good weather resistance.

It is possible to build externally exposed oak frames that meet and exceed Building Regulations. Additionally, encapsulation systems have been developed which completely insulate the frame externally, minimising the cold bridging effect of the timbers and providing a draughtfree environment. Several oak-framing companies have developed their own prefabricated encapsulation systems and most well-made, exposed oak frames – with the proper detailing – perform exceptionally well on airtightness tests.

Oak, unlike many other timbers, does not require preservative because the wood is naturally resistant to insects and weathering, although the frame can become marked from the natural tannin in the wood. These marks and other stains from the building process can be removed by sanding or using oxalic acid once the frame has been built.

-

-

DRAWINGS PRODUCED BY

T.J. Crump Oakwrights Ltd The Lakes, Swainshill, Hereford, HR4 7PU

QUEEN POSTS SLING

+44 (0)1432 353353 enquiries@oakwrights.co.uk

© This drawing, its contents, and all information contained therein is protected by Copyright. It may be used once only for its intended purpose under a contract with T.J. Crump Oakwrights Ltd, but not for any other use or purpose. This drawing is for Planning purposes and does not constitute a construction issue drawing. All setting out dimensions and levels are indicative and are subject to detailed site survey and site conditions. The Client and their agent are responsible for ensuring that Building Control and construction drawings are carried out following Planning approval. Scaling from this drawing is for Local Planning Authority information only.

CLIENT

WALL PLATE

Mr& Mrs XXX

SITE ADDRESS

GIRDING RAIL

XXXXX PROJECT

New Dwelling

CHAMBER BEAM

DEPARTMENT

ESTIMATING

DRAWING

Oakwrights

TIE BEAM GLAZING STUD

JOWL/BAY POST

FRAME ELEMENTS

SCALE

N/A

DATE DRAWN

XXXXXXXX

BRACE

DRAWN

SOLEPLATE

DRG. NO.

of the available options. Many standard designs can be adapted to create individual houses, and in-house designers and architects can produce bespoke plans and elevations, including detailed drawings for Building Regulations.

It is possible to build a very contemporary home around an oak frame, and if a structural engineer specifies additional steelwork to reinforce the building this can be concealed within an oak beam. Alternatively, traditional frames are based upon the design and style of the vernacular oak frames found in English towns and villages.

There is no county in England without examples of oak framing and this can be extremely useful in persuading local authorities to grant planning permission.

A popular option is the barn-style oak frame, which combines the contemporary and the vernacular. The essential difference is that the beams are not generally exposed externally. These buildings invariably have a more openplan feel, with fully vaulted roofs, and the heavy oak frames are well suited to accommodating large areas of glazing.

Some package companies will undertake everything from gaining planning permission and erecting the frame to organising subcontractors and completing the entire project on your behalf. Others will simply design, supply and erect the oak frame, leaving the selfbuilder responsible for organising everything else.

DIAGRAM The main components of an oak frame.

PICTURE OPPOSITE Oakwrights' show home outside Hereford where potential clients can stay overnight to experience what it’s like to live in an oakframe home.

XXX

DATE ISSUED

XXXXXXXX

CHECKED

XXX

REV.

FRAMING

MAINTENANCE

Some oak-framing companies continue traditional framing techniques, passed down through generations, with hand tools still very much in evidence. Others favour fast, computer-controlled cutting machines.

The oak is used soon after it is felled so that the green timber is easy to cut and work into the desired shapes.

Green, unseasoned oak is traditionally assembled with classic wooden pegged mortise and tenon joints, and the timber continues to contract – tightening the joints to give a uniquely strong structure which will last for centuries.

Most companies make up the entire frame at their framing yards prior to dismantling it ready to be delivered and re-erected on site. The finished building will also need to incorporate modern materials such as air barriers in order to meet Building Regulations.

It is important to find out the lead (waiting) time

Untreated oak weathers to a silver-grey colour externally, while remaining deep golden inside. As the oak seasons it hardens to a nail-bending density, so carpenters tend to work the wood while it is fresh and unseasoned. Oak is described as ‘green’ when it has been felled only a couple of years and the timber still has a high water content and is not dry in the middle.

It then takes between five and 10 years for an oak beam to dry out completely and season, and this process often results in shrinkage and movement – a factor which can alarm homeowners. As the oak dries and shrinks, the process creates minor splits or ‘shakes’, which are all part of the building’s charm but can cause a few creaks and groans to emanate from the timbers. Oak can be exposed externally without any need for artificial coatings and is extremely resistant to insect attack. For wood to rot there

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must be a serious damp problem, as moisture passes through wood unless covered in materials such as cement render.

COSTS Oak framing is often seen as an expensive building option, with oak costing at least one-third more than other timbers. In general, though, oak construction will only increase the overall cost by between five and 10 per cent and the simpler the design, the less expensive the frame. Resale values are high and there are ways to reduce costs and ensure that you get maximum value from the exposed frame without breaking the bank.

One option is to combine this form of building with a less expensive alternative, such as blockwork and areas of softwood framing. By building just one section of a house using an oak frame you can benefit from all the advantages of the wood in prominent areas like vaulted hallways and sitting rooms. Known as ‘hybrid’, this method is ideal for those on a more limited budget who wish to feature some oak within their home.

8

top TIPS

By Helen Needham RIBA ARB Architect, head of architecture at Oakwrights 1. MAKE A WISH LIST Refine your ‘wish list’ of spaces – in words, or even your own sketches – what are the essential components of your brief? This will be room uses; number of bedrooms etc, and may also extend to what you have always desired from your oak-framed home, such as wanting a galleried landing, a picture window, a wow staircase that is framed by the oak, or something designed around pieces of furniture or paintings you own. Whether big or small, your wishes matter and drive the project – this is your opportunity to create your bespoke dream home.

2. CHOOSE A STYLE Oak is a really versatile product, bringing quality and character to a new home. The exteriors are extremely adaptable with a variety of materials and proportions – would you like a traditional, country, or contemporary appearance? You may have seen barn, cottage, farmhouse, single-storey, or other styles that catch your eye. Collating examples helps to channel the design and allows your architect to understand your tastes, so keep those magazine cuttings, and create that Pinterest board.

3. SET A BUDGET Do you have a build budget that you need to work to? A design should be tailored to this. Or do you need guidance?

Again, options can be given to refine this for you. Indeed, monitoring the build budget throughout the whole process is vital – you want to ensure that what is designed is buildable when you arrive at that exciting stage. Buying a standard design from a range will help you to budget better and save on design fees. A turnkey service will allow a professional project manager to manage your build and your budget.

4. USE A SPECIALIST Working with an oak framing specialist who can guide you through the important planning and technical design steps is essential. They will ensure the layout and design will work well for an oak frame and is buildable. You need to get on well with your design team, to trust that they listen to your wishes, and also to ensure they are professional and experienced, and will support you throughout. Understanding their processes and what they produce is essential – will they be creating 3D software images at the early stages for you to visualise your design? Will they be liaising with oak frame and encapsulation designers at the concept stages? This is all key to ensure the services and expectations of both parties are clear.

5. GET THE PLAN RIGHT The position of the main habitable spaces and stairs is essential, while carefully considering those equally important ‘working’ sides of the house – for ancillary areas such as side entrances, boot rooms, utility etc. Oak may not be necessary for these sides and can be built in structural softwood. As a rule, the clear span between oak posts should be no more than five metres - though with additional posts or steels, larger spans can also be achievable. In open-plan areas, the oak framing works perfectly as it creates zones and visual separation. Vaulted spaces and fully exposed oak framing can make the most of the aesthetic appeal of the oak. We can start to divide and ‘sculpt’ spaces to give a frame the right amount of proportion and balance on the eye within a room. The oak frame designers provide creative ideas using terms such as cruck, arch-braced collar frames, scissor trusses, and dragon ties!

6. SIGNING-OFF STAGES For any build to go well, a good design is paramount. A good design team has the ability to design any style, shape, or size of house. At Oakwrights, once the design is agreed we also handle the planning submission. When planning is approved by the local authority we then start the process with the finite oak framing details with our frame designers to create a buildable and costeffective frame. From the early stage we are considering the next technical design stage – so, for example, the soil pipes are considered alongside the oak frame. It is important that each of these stages is signed off by the client.

7. QUALITY IS KEY Selecting the right manufacturer and product for your build is important. The building fabric is key to the future comfort of your home and will also affect planning and Building Regulations – building to a green agenda will assist with both. Insulation and airtightness are essential parts of the construction, reducing energy consumption and lowering heating costs. A post-and-beamstyle home, ie with the main oak structure on the inside, wrapped with an insulated encapsulation system, will create the most energy-efficient method. Our wraparound encapsulation systems will encase your bespoke frame, using either our Wrightwall (PIR foil-backed and mineral wool insulation) or the Wrightwall Natural (recycled newspaper option). The amount and orientation of glazing also need to be carefully factored in. You may even go on to require Passivhaus levels (we built the first two and only oak-framed Passivhaus buildings in the UK).

8.THE SYSTEM How the frame is produced is also important – ensuring there is precision and quality control in the workshop.

Understanding how a building will be constructed can enable you to save time and cost at a later stage. The off-site production of an oak frame can allow you to press on with the enabling works, while the oak frame is being designed and constructed under workshop conditions. The structural oak frame could take as little as a week to erect.

With the encapsulation wrapped around it you could have a dry shell within four to six weeks.

structuraltimber.co.uk / BUILDING WITH TIMBER

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In association with

New dream oak home Derek and Elizabeth Sandeman haven't regretted their decision to replace a tired bungalow with a new oak-framed country cottage.

H

aving lived in their period property in a pretty New Forest village for nearly 20 years, Derek and Elizabeth Sandeman began considering the possibility of downsizing. “Our children were leaving home, so we decided to move somewhere smaller,” explains Elizabeth.

“As we love the village, we didn’t want to go too far.”

The couple’s search was largely unsuccessful until one day they noticed a listing for a bungalow on a large plot and immediately made an appointment to view it. “It was in the right location but the ugly bungalow was in a dark corner,” Elizabeth recalls. “We bought it with a plan to replace it with a house in a more central position.”

EXTERIOR The new home is more centrally located on the plot than the former bungalow to take advantage of the bucolic country views.

The oak frame is clad in timber to blend in with the surroundings.

“Because we have a highly insulated fabric in the house, we need little heating and have much lower fuel bills.”

Derek and Elizabeth hadn’t previously considered a new build but they could see the plot’s potential and began contemplating building a house bursting with character and charm. They could picture living in a home that worked in harmony with the natural surroundings they loved.

Following research, they found Oakwrights and saw a photograph of its Herefordshire show home, The Woodhouse. “It was perfect, with lots of beams and a warm atmosphere,” says Elizabeth. “We went to stay at the show home and loved it so much, I didn’t want to leave.”

Derek and Elizabeth knew they wanted to build an oakframe home, and began working with one of Oakwrights’

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BUILDING WITH TIMBER / selfbuildanddesign.com

HOMES OAK-FRAME COTTAGE

LIGHTING The house and garden come into their own in the evening with clever lighting.

structuraltimber.co.uk / BUILDING WITH TIMBER

33

HOMES OAK-FRAME COTTAGE

regional architectural designers, John Williams. They came up with a barn-style design that would sit more centrally on their plot. This orientation placed their new home closer to an existing garage and would harness their views and the sunlight.

To ensure their house would provide the space they required for years to come, Derek and Elizabeth decided to build a basement for additional storage. This was approved by the planners, as it was not included in the floor area or volume limits set by the council.

With planning approved, the Sandemans sold their period property and moved into the bungalow, living there while work was completed on their new build next door.

The oak frame was prefabricated at the Oakwrights Herefordshire workshop and erected on site in just four days, along with the WrightWall and WrightRoof Natural encapsulation panels that wrap seamlessly around the frame. The encapsulation allows walls to breathe and is built with high insulation levels to retain comfortable internal room temperatures all year round.

“Because we have a highly insulated fabric in the house, we need little heating and have much lower fuel bills,” explains Elizabeth. “We’re absolutely thrilled with it and so glad we made the decision to build.”

OAK ON SHOW The oak beams can be clearly seen in the central dining room and the main bedroom, which has a balcony.

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BUILDING WITH TIMBER / selfbuildanddesign.com

KITCHEN The barnstyle home has a warm country feel, with a large dresser in the hall and oak flooring matching the beams on show.

Oak beams can also be seen in the modern kitchen.

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CLT construction explained As a relatively new innovation, cross-laminated timber is strong and versatile, and can be used for a range of applications, from walls and roofs to floors and even stairs.

K

nown as CLT, cross laminated timber was pioneered in Europe in the 1970s and is imported to the UK, mainly from Austria, Germany and Scandinavia.

The cross-layered engineered wood is particularly strong and its versatility has seen it used in many ways in construction, from walls, roofs, and floors to stairs. One of the most exciting aspects of CLT panel construction is its potential to overcome the height limitations of traditional timber structures. A striking example is the Mjøstårnet tower block in Norway which was built using CLT. Built in 2016, it is the world's tallest timber building, standing at an impressive 85.4m high.

CLT structures are typically built using a platform frame where walls are temporarily braced with raking props before floor panels are lowered onto them and fixed.

The completed floor structure provides the ‘platform’ for the erection of the wall panels to the following storey.

For those with more modest aspirations, CLT panels have practical applications for the housebuilding sector too. For example, pre-insulated wall and roof cassettes are suited for room-in-the-roof construction where there is a simple arrangement of continuous ridges and gable ends.

A breathable roof underlay and rigid insulation are usually installed above the CLT panels for a warm roof construction which can be prefabricated as an insulated cassette.

So what gives CLT panels their inherent strength and stability? Basically, it is the way they are formed.

Multiple layers of cross-bonded timber, typically 20mm to 45mm thick, are glued together. The number of layers is always odd, with a minimum of three, and

CLT is mainly imported from Europe.

Stora Enso in Austria recently invested £7m in a coating line to provide protection to the panels against moisture, sunlight, insects and fire. As a sustainably sourced material, CLT can help meet carbon offset requirements and lower the footprint of a building’s entire life cycle.

CLT's inherent strength means it can be used on timber bulldings to achieve heights previously thought impossible.

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BUILDING WITH TIMBER / selfbuildanddesign.com

these layers may be of varying thicknesses, arranged symmetrically around the middle layer. The panel’s strength is achieved by having the grain of each layer at right angles to each other. The overall thickness, as well as the load-bearing performance of the panel, is determined by the build-up of the individual laminates.

The benefits of CLT over conventional softwood wall framing and joisted floor constructions include its large axial and flexural load-bearing capacity when used as a wall or slab, its high inplane sheer strength (resistance to wind and seismic forces), and its fire resistance. As a solid wall panel, rather than a framed construction with loadbearing post elements, CLT panels also distribute their weight evenly as in-line loads at foundation level, which reduces the requirement for localised pad foundations.

Other pros include good acoustic performance and excellent thermal insulation which can be used to achieve good U-values, typically 0.13W/m2K for the building envelope.

In association with

Glulam beams Glulam is another form of laminated timber. Unlike CLT panels, it is used in lengths and is an alternative to concrete and steel beams.

Although it is broadly considered a modern building material, its origins date back to the late 19th century.

A Swiss patent in 1901 heralded the true beginning of glulam which consists of layers of timber glued together with a moisture-resistant adhesive. The timber is manufactured in a factory where the laminated layers, usually made from softwood such as spruce, larch or fir, form a larger, single element which can be used for a range of applications, from beams for large spans, to lintels and posts. Glulam can be made to virtually any shape, and its light weight makes it practical to handle.

Because of its natural good looks, glulam is often left exposed and can frequently be spotted in sports hall roof structures and in numerous commercial buildings such as supermarkets, serving as both a decorative and structural component. Glulam is often used in place of concrete and as an alternative to RSJs or a steel frame. Surprisingly, it can outperform steel in a fire where the latter distorts in high temperatures. The timber surface of glulam may become damaged, but the integrity of the shape remains intact.

Glulam is considered a greener alternative to concrete as it has a 60 per cent lower carbon footprint. In house construction it is often used to span large open-plan spaces, creating a striking contemporary feature in the process.

structuraltimber.co.uk / BUILDING WITH TIMBER

37

A-Z MEMBERS Picture: Taylor Lane

Directory It is important to note that it is not always feasible, possible or necessary for a member to achieve a Gold-level membership. Specific quality requirements dier for each type of member and customer activity depending on the nature of a company’s business; therefore, a Bronze or Silver member may be the most appropriate company for your project requirement.

KEY TO MEMBERS

BRONZE MEMBER

SILVER MEMBER

GOLD MEMBER

OAK FRAME Oakwrights Limited oakwrights.co.uk 01432 353353

SIPS Eurosips Energy Eicient Homes eurosips.com 01279 413535

Timber Innovations Ltd

Frame Technologies Ltd

timberinnovations.co.uk 0121 314 7735

frametechnologies.co.uk 01544 267124

TIMBER FRAME

FrameWork Synergies Ltd

A1 Timber Frame

fwsl.co.uk 0800 085 3341

a1timberframe.co.uk

01639 894329

Glosford Timber Solutions

FREDS Timberframe Ltd

glosfordsips.co.uk 01432 842999

Allwood Buildings Limited allwoodtimber.co.uk

fredstimber.co.uk 01792 966455

JML Contracts Ltd

Bartram Timber Frame Ltd

Gibbs Timber Frame Ltd

jmlcontracts.co.uk 01764 663271

bartramtimberframe.co.uk 01767 699699

gibbstimberframe.co.uk 01983 522188

Poon

Cornwall Timber Build

Horton Timber Homes

poon.co.uk

01767 676400

cornwalltimberbuild.co.uk 01579 364932

hortontimberhomes.co.uk 01327 460421

SIP Build UK Ltd

Craiglea Timber Frames td

Hybrid Houses Ltd

sipbuilduk.co.uk

01977 520902

craigleatimberframes.co.uk 07791 288795

hybridhousesltd.com 07850 406406

SIP Building Systems

Danwood House

Kestrel Timber Frame Ltd

sipbuildingsystems.co.uk 0151 420 1404

dan-wood.co.uk 01896 752271

kestreltimberframe.co.uk 01778 348173

SIPCO Ltd

Deeside Timberframe Ltd

Kudos

thesipcompany.com 0151 424 5346

deesidetimberframe.com 01569 767123

buildingkudos.com

SIPS Industries

DG Timber Solutions Ltd

Lakeland Timber Frame Ltd

sipsindustries.com 01383 823995

dgtimbersolutions.co.uk 01933 653818

lakelandtimberframe.co.uk

SIPS UK

Fforest Timber Engineering Ltd

sips.uk.com 01933 353501

orest.co.uk 01792 895620

SIPS@Clays LLP

Frame Homes/Frame UK

Marconi Builders & Developers Ltd

clays.com 01756 799498

framehomes.co.uk 01209 310560

marconibuilders.com 01326 562519

028 9083 8951

Maple Timber Frame

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BUILDING WITH TIMBER / selfbuildanddesign.com

mapletimberframe.uk 01995 679547

In association with

MBC Timber Frame

Wyder Engineered Timber Systems

MD Insurance Services Ltd

mbctimberframe.co.uk 01452 346499

wydertimber.co.uk 01772 780175

Merronbrook Ltd

MULTI-FRAME OPTIONS

07771 918321 daniel.hughes@mdwis.co.uk premierguarantee.co.uk

merronbrook.co.uk 01252 844747

Flight Timber Products Ltd

MTE (Leicester) Ltd

flighimber.com 01787 222336

mte-leicester.co.uk 0116 232 1777

Norscot Joinery Ltd

Scotframe Timber Engineering Ltd

Warranty provider

Buildstore Mortgage Services Limited 0345 223 4888 tom.mcsherry@buildstore.co.uk buildstore.co.uk

Mortgage & funding

scotframe.co.uk 01467 624440

Evolved Design Ltd

Paramount Timber Frame Ltd

Kingspan Timber Solutions Ltd

01691 778846 sue@evolved-design.co.uk evolved-design.co.uk

paramounimberframe.com 01634 893821

kingspanosite.com 01767 676400

Premier Timber Systems

Lowfield Timber Frame

premiertimbersystems.co.uk 01924 335735

lowfieldtimberframes.co.uk 01743 891922

Rob Roy Homes (Crie) Ltd

OTHER MEMBERS

robroyhomes.co.uk 01764 670424

Olive Modular ltd

norscot.co.uk 01955 641303

Sevenoaks Modular Ltd somodular.co.uk 01639 620240

07930 025583 jonathan@olivemodular.com olivemodular.com

CLT

Target Timber Systems Ltd

ABC+ Warranty

targeimber.com 01403 782600

0161 928 8804 info@architectscertificate.co.uk architectscertificate.co.uk

Taylor Lane Timber Frame

All services

taylor-lane.co.uk 01432 271912

Protek Group Ltd

The Timber Frame Company fcuk.co.uk 01582 635888

07584 039194 simon.middleton@protekwarranty.co.uk protekselfbuild.co.uk

Point1 Building Systems Ltd

thomasarmstrong.co.uk 01900 68211

01743 460066 garry.dyke@point1buildingsystems.com point1buildingsystems.com

Timber Frame Management

Installer

Timber Frame Technology UK timberframetech.co.uk 01525 370372

Self build centre

Allan Corfield Architects Ltd 01383 737101 allan@acarchitects.biz acarchitects.biz

Architect

Thomas Carter Ltd 01892 724710 gerry@thomascarter.co.uk thomascarter.co.uk

SIPS installer To find a member, including supply chain companies for insulation and membrane, use the STA search engine: structuraltimber.co.uk/members

01732 742102 peter.richardson@sennocke.co.uk sennocke.co.uk

Warranty provider

Neat UK Ltd

timberkitsolutions.co.uk 01952 770990

0141 297 1927 colin.taylor@neat-living.com neat-living.com

Truro Timber Frame Ltd

All services

trurotimberframe.com 01872 519494

Mary Riley Solutions Limited

turnertimber.co.uk 01482 218945

01506 409464 philip.wilson@nsbrc.co.uk nsbrc.co.uk

Sennocke International Insurance Services Limited

Timber Kit Solutions Ltd

Turner Timber Frames

The Homebuilding Centre Ltd

Warranty provider

Thomas Armstrong Ltd

timberframemanagement.co.uk 01553 692771

Designer

01794 399966 mary@maryrileysolutions.co.uk maryrileysolutions.co.uk

Mortgage & funding structuraltimber.co.uk / BUILDING WITH TIMBER

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