Straw bale building Training for European Professionals: Wrapping

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INDEX

U4 – WRAPPING (EXTERIOR THERMAL INSULATION)

U4 TIME

PAGE 5

U4 Session 1 : Design and Planning ca. 6 hrs.

Info: Thermal Insulation Composite Systems in Relation Info: Design and Planning: Details (Foundation/Windows) Tipps: Planning-Checklist Wrapping

7 8 12 14

U4 S2: Constructions Info: Wrapping-Konstruktionssysteme Tipps: Konstruktionssysteme

2 days

21 22 24

U4 S3: Prefab-Constructions Info &Tipps: Wrapping-Prefab-Systems

1 day

U4 Learning Outcome

001 -1 4 Hybrid Foundation, 002-1 5 Perimeter-Insulation, 003-1 6 Drainage, 004-1 7 Roof Overhang, 005-1 8 Windows and Doors, 006-19 Scaffolding

007-24 CUT centered, 008-25 CUT outside, 009-26 Binding Bales to the Wall, 010-27 Spanning Bales down, 011 -28 Spanning Bales to the Wall, 01 2-29 PalletteHybrid-Constructions, 01 3-30 Cage for Bale Layers, 01 4-31 Drop Nose, 01 5-32 Direct Plaster, 01 6-34 Cladding , 01 7-35 Glass Facade

37 38

01 8-38 system/haus/bau / ASBN, 019-39 Jules Ferry Residence / Bet Gaujard, 020-41 Complemedis / Werner Schmidt, 021 -42 Straw/Reed-Facade by Kengo Kuma Ass., 022-42 Waseda University Students: A-Recipe-To-Live-Straw-House, 023-43 Enterprise Centre of University East Anglia: Prefab Straw-Reed-Facade, 024-43 Schelfbauhütte: Montage System for Straw Bale-Wrapping, 025-44 School Montreuil and Issy les Moulineux: Exterior Modular Straw Bale Facade, 027-45 Make your City Smart! / Paul Schulz, TU Vienna, 027-46 Calculation Building Costs

U4 S4: Alternatives to Straw Bales Info &Tipps: Natural NAWARO-Alternatives

ca. 2 hrs.

023-47 Inject Straw Fibres, 024-48 Straw Mats, 025-49 Reed Mats

Credits and Impress

49 49 52

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LEARNING OUTCOMES

U4 Level 3 (ECVET credit points: 1 5) / Level 4 (12)

Knowledge Trainees know …

• about the existing national building regulations related to straw bale building.

• the specific problems organizing a wrapping straw bale building site and their solutions (weather protection, safety, logistics).

• the symbols to be able to understand plans and construction drawings.

• new and historical wall-constructions and their impact on wrapping (horizontal moisture barrier, position ofwindows, consistence of plaster, roofoverhang).

• the different methods and techniques of wrapping, their requirements, advantages and disadvantages.

• the necessity and the techniques to avoid and to close gaps (between bales and between bales and construction).

• other bio-sourced insulation materials, that can be used additionally in straw bale building.

• different fixings and their characteristic and the suitable methods of compressing.

• different wrapping techniques and their requirements related to schedule, planning, budget and resources.

• about techniques and construction details for the adjacent building elements (ceiling, walls, floor- and roofplates) avoiding cold bridges.

• techniques to manufacture the additive base plate for straw isolation avoiding cold bridges.

• the reasons and the techniques to prepare the substrate with a plane and gap free surface.

Skills Trainees can …

• control the quality ofexisting constructions in relation to its suitability for wrapping straw constructions.

• handle the tools and machines which are used in wrapping construction.

• apply different wrapping and retrofitting methods professionally.

• resize and fix the bales and kompress them if needed.

• fix the bales on an existing wall and fill gaps with straw or another suitable sustainable insulation material in order to produce a continuous layer of insulation avoiding cold bridges.

• make a lasting connection between the wrapping and the existing construction.

• read and understand the symbols of plans and construction drawings.

• make supportive wooden structures and posts and lintels for the openings.

• give advice to others, who make the plinth wall and other requested details.

• prepare the substrate for following crafts (plaster, cladding, air- and wind tightness) or execute it in accordance with them (level and shave the straw surface, fix the plaster ground on wooden construction elements).

Competence

Trainees can …

• organize and attend the building site at all stages and adapt the working process, the use oftools and adequate techniques related to straw bale wrapping (planning, preparation, execution, additional crafts).

• coordinate and communicate the special needs of wrapping constructions with other professionals.

• explain different methods ofwrapping with straw with reference to advantages and disadvantages.

• select good quality bales for wrapping and supervise the whole wrapping process during the construction period.

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SESSION PLAN S1

U4 – WRAPPING (EXTERIOR THERMAL INSULATION)

U4

Session Plan U4-S1 : Design and Planning Objectives: Trainees ... … have the ability to read and understand architectural plans and construction drawings. … know different structural options. … know the advantages and disadvantages of every solution.

Skills:

Make a building schedule Organize and finish the work according to schedule Make a cutting list Calculate the building costs

Trainer:

Place:

Classroom

Duration: 3 days

Equipment: Beamer Flip chart

Methods:

Theory

Lecture/talk Explanations Practice Basics of architectural plans and construction drawings Different structural options, characteristics and bale requirements Advantages and disadvantages of different techniques How to prepare a building schedule How to make a cutting list Calculation of building costs (material, labour etc.)

Practice

Study and develop a case-study comparing the results with other trainees.

Organization:

Prepare a case study for every group of trainees (2–3 persons), study it in order to be able to compare it with the results of the participants.

Documents:

Info sheets: I1 Drawing basics I2 Characteristics of different options I3 Drawings of pros and cons Text sheets: X1 Drawing basics X2 Characteristics of the different options X3 Organization of building site and schedule Exercise sheets: E1 Make a building schedule E2 Cutting list E3 Calculating material and costs E4 Drawing construction details

Evaluation:

Multiple choice

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INFO 1

U4-S1-I1 : thermal insulation composite system U-Wert: 0,1 32 W/m 2K PEI n.e.: >1 9 kWh/m²

Straw Bales with Direct Limeplaster Bale density ca. 100 kg, complete 38,5 cm thick Surface: shaving, stuffing, plastering Wrapping-System: Material Price/m2 (AT) Straw Bales: around € 10,00 - 1 7,40/m2 (cert.)

Constr. with/out window box: € 1 3,05 - 36,50/m2 Lime plaster 2,5 cm, mesh, Rabolin: € 10,00/m2 Material-Price complete: € 33,05 - 63,90/m2

U-Wert: 0,1 28 W/m 2K PEI n.e.: >23 kWh/m²

Straw Bales with ventilated Cladding Bale density ca. 90 kg, complete 45 cm thick Wrapping-System: Material Price/m2 (AT) Straw Bales: around € 10,00 - 1 7,40/m2 (cert.)

Constr. with/out window box: € 1 3,05 - 36,50/m2 diffusion open facadeboard (DWD): € 8,46/m2 Batten, Counterbatten, Cladding: € 40,00/m2 Material-Price complete: € 71,51 - 102,36/m2

U-Wert: 0,1 78 W/m 2K PEI n.e.: >1 3 kWh/m²

Naporo Hempmat + Capatect Facade 20 cm Hemp Board/Mat, complete 21 cm Wrapping-System: Material Price/m2 (AT) Hempmat (Naporo): 24,91 - 41 ,52/m2 Screw dowel, filler, plaster base, fibre glass mesh, CarboPorPlaster: € 24,80/m2 +/-Windowbox with Insulation: € 23,45/m2 Material-Price complete: € 50,00 - 89,77/m2

U-Wert: 0,1 73 W/m 2K PEI n.e.: >1 3 kWh/m²

Mini-StrawBales, Woodfibreb., Lime-Directplaster 26 cm Straw, 4 cm SteicoProtect, compl. 32,5 cm Wrapping-System: Material Price/m2 (AT) Straw Bales: around € 8,00 - 11 ,20/m2 (cert.)

Constr. with/out window box: € 1 3,05 - 36,50/m2 diffusion open facadeboard: € 1 3,1 8/m2 Lime plaster 2,5 cm, mesh: € 8,70/m2 Material-Price complete: € 43,00 - 69,58/m2

U-Wert: 0,1 74 W/m 2K

PEI n.e.: >1 33 kWh/m²

to compare: Baumit WDVS EPS-F 1 8 cm EPS-F, complete ca. 20 cm Wrapping-System: Material Price/m2 (AT) EPS-F (Polystyrol-Insulation): 22,60/m2 Adhesive filler, fibre glass mesh, primer, SilikatTop: € 1 7,09/m2 +/-Windowbox with Insulation: € 23,45/m2 Material-Price complete: € 40,00 - 63,14/m2

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Prices: baustrohballen.at/sonnenklee.at/frischeis.at/haeuser-in-wolle.com/bauschilf.at/hagebau.at

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U4 – WRAPPING (AUSSENDÄMMUNG)

U4-S1-I1 : thermal insulation composite system

Source: u-wert.net, infos without warranty

INFO 1

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U4-S1-I1 : thermal insulation composite systems in relation

INFO 1

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U4-S1-I1 : thermal insulation composite systems in relation

INFO 1

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Session Plan U4-S1 : Design and Planning

INFO 2

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Session Plan U4-S1 : Design and Planning

INFO 2

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Session Plan U4-S1 : Design and Planning-Checklist

Task: Calculate PEI of this foundation per m

001 insulated HybridFoundation: Concrete or not Concrete?

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In order not to have to build with organic, moisture-sensitive materials in the splash area, we have to somehow overcome the 30 cm - with a base or auxiliary foundation. In general, this is made of concrete, although we don't have much loads except a plastered straw ball wall. What actually speaks against concrete? Concrete is an artificial mixture of cement, sand or gravel and water. Usually. further additives are used. The required energy expenditure for the production of concrete depends essentially on the composition of the concrete. The component with the highest energy content is the cement. Furthermore, a distinction is made between reinforced and unreinforced concrete. The reinforcement degree has a significant influence on the production energy PEC (transport concrete C20 / 25: PEI: 31 5 kWh / m3, λ = 2.0 W / mK, concrete blocks: PEI: 379 kWh / m3, λ = 1 ,35W / mK).

Advantages Concrete: High compressive strength, good sound insulation, good fire protection, good moisture protection, high thermal mass, any shape Disadvantages Concrete: poor thermal insulation, aging process, "composite building material".

Thermoblock-Bricks have an even higher primary energy content (perlite filled) Brick S, Poroton: PEI: 484 kWh / m3, λ = 0.09-0.11 W / m.K) One possibility is to reduce the proportion of concrete as much as possible and to use mineralic, insulating building materials instead. However, their properties are also very different: perlite (PEI: 1 87 kWh / m3, λ = 0.06 W / mK), foam glass (PEI: 224 kWh / m3, λ = 0.07 W / mK), Leca (PEI: 850 kWh / m3, λ = 0.035 W / mK) as well as XPS have a higher primary energy content than concrete (PEI: 548 kWh / m3, λ = 0.1 6 W / mK) ) Solution: 1 5 cm concrete blocks with perlite or foam glass. Thus, the primary energy content remains justifiable.

Source ofallValues for PEC und λ:TU Munich

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Session Plan U4-S1 : Design and Planning-Checklist

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002 Foamglass-gravel and Cork Perim.insulation instead of XPS Are there any ways to prevent concrete and XPS in the wrapping foundation and perimeter insulation? The starting price for comparison is: € 9.74 / m.

If we take a single-storey building (3 m high), we have a static load of straw bales (100 kg / m3 = 108 kg / and lime plaster (1 400 kg / m3 = 105 kg), thus total of 227 kg / m foundation. This is comparatively little load. Furthermore, these wrapping loads are not carried completely by the foundation, but partly by the wall and the roof rafter (suspended construction). And the 6 cm foot threshold distributes the unequal loads.

Now we know that foam glass e.g. is suitable as a capillary, heat-insulating and loadbearing layer under ground level. 30-40 cm foam glass gravel around the house are enough (price at 50 cm depth € 11 ,70 - 1 5,70 / m). In order to overcome the 30 cm above ground level, Mirapor proposes so-called wall bags. Foam glass could also be filled into gabions (30 x 30 x 30 cm: € 8.95) or as in the case of the Earthbags (Calearth), filled into PP sandbags (€ 0,83, 4 rows of á 40 x 60 cm = € 6.46 / mm).

Another alternative is cork as perimeter insulation. Cork should not be placed directly on the damp ground, but it can bridge the 30 cm on top of foam-glass gravel (price at 10 cm thickness and 30 cm height: 1 2,53 / m). A lime-cement plaster with glass fiber mesh ensures that this auxiliary foundation does not settle. But: without guarantee!

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Session Plan U4-S1 : Design and Planning-Checklist

003 Advantages and Disadvantages of Drains in Restoration

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In the restoration and clearing of old building cellars no drainages are generally found. This has its good reason in building the floors of these basements. In many of the cellars, for example, only a loose brick is laid in the Wilhelminian era, which does not have any kind of sealing against the ground. If foundations are built, they are usually water-permeable and in no way waterproof concrete. On the outside, the floor materials were again installed in a slightly compressed manner, so that at the base of the walls only capillary moisture - ie soil moisture, which could not be removed by drainage - is present. If the soil situation remains the same, the installation of a drainage tube would be completely ineffective, since a drainage pipe only drains water in liquid form.

The installation of a drainage system with leachable granules, drainage plates and drainage pipes on the exterior walls and foundations would considerably impair these cellar constructions. Water would permanently flew into the open-pore and leachable drainage package next to the basement, which would lead to continuous water input and damage on walls and foundations. In particular, the soil moisture present to date under the basement floor would convert to a moisture saturation of the soil, which could not be relieved by a functional drainage at the exterior side of the walls.

Respecting this, drains in old buildings are not purposeful and usually senseless, especially since a drainage in water-bearing soil layers would only bring about a reduction in the water amount. (Source: trockenlegung-hannover.de/drainagen)

TIPS

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U4 – WRAPPING (EXTERIOR THERMAL INSULATION)

Session Plan U4-S1 : Design and Planning-Checklist

TIPS

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004 Is there enough Roof-Overhang lateral and on gable-side?

Roof overhang lateral: the distance from the façade to the respective eaves (drip edge); Roof overhang at the gable-side (Ortgang) beyond the façade.

While the extension of the lateral roof overhang is relatively simple, static calculations are mandatory when the roof overhang on the gable-side is extended.

The administrative background has also to be added to the effort. When you renew the roof overhang at the gable side, you will have to obtain a building permit. In addition, building laws define a minimum distance to adjacent areas and also to the road. Finally, in many cases the neighbors will also have to confirm their agreement in writing.

This also means that you need a structural engineer or architect who can design and sign the appropriate blueprints before submitting them to the building authorities for approval.

Please check, before you cover an outer insulation, the roof overhang on all sides, for the wrapping with straw you need in the minimum case 36 to 40 cm on all sides.

If this space is not available, it is advisable to think about thinner thermal insulation layers (for example with 26 cm minibales, flakes or other insulation) (see page 8 or tip 01 3). Or you extend the roof unconventionally: with a short extra roof under the main roof above the wrapped straw bale wall. This could be covered for example with a metal sheet (roofer / plumber, see picture on the upper right).

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Session Plan U4-S1 : Design and Planning-Checklist

005 Solid Boxes carry the (new) Windows and Doors:

If windows are left in the existing wall (e.g. because they still correspond to the thermal insulation standard), a thermal bridge is created because the straw bale wrapping insulation is completely open here. Windows are always the weak point in any house (8 - 1 2 cm wood or plastic frame has a significantly worse insulation value than 36 cm straw). In this case, the window frames must be massively insulated (outside), but this usually causes a problem (from the wall to the window wing it is usually not more than 5-6 cm).

So windows are ideally removed and placed in the insulation area. Sturdy boxes (the larger the window or the (terrace) door, the more solid) are used for this purpose, which are pushed into the cavities after removal and are laterally fixed (and insulated). Concrete formwork panels meet these requirements better than OSB and are cheaper than natural three-layer panels. In addition, their impregnation provides a double rain protection (window sill). On the front, they are attached to our hybrid posts. The window sill is slightly sloped (2 °) and because the additional 40 cm insulation layer greatly reduces the amount of sunlight the box can also be beveled outwards (45 °). It is simpler, however, to extend the box only 1 8 cm to the center of the straw bale (where the windows are then installed at the front edge of the box) and the angle before is produced by cutting the bales (alligator / hedge trimmer).

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Session Plan U4-S1 : Design and Planning-Checklist

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006 Safety and Efficiency: Do we need a Scaffolding?

Anyone who has lifted a 1 4 kg strawbale on a ladder standing in front of a wall and does not have the muscles of Arnold Schwarzenegger can sing a song of it: a scaffolding helps not only to save energy (and to not leave the motivation), it also helps to maintain the quality of the installation. Bales need to be compressed downwards with your weight (feet) or the persuader (wooden hammer) and with additional flakes to close the gaps to the adjacent bale, they must also be installed as flush as possible in a level with the neighboring bales ( so that we get a flat surface for the subsequent plaster). We are talking about quality work, which can only be done on a safe scaffolding. In single-storey houses, you may work perfectly with a few stable bucks and scaffolding boards. Or a smaller sliding aluminum scaffolding (which can be rented easily and cheaply, e.g. at geruestverleih.at: â‚Ź 70, - / week). In two-storey buildings it is advisable to have a scaffolding erected by a scaffolding builder or master builder, as it can be used also by other craftsmen (e.g plasterers and roofers). Saving money here can ultimately become more expensive as not only the motivation of the straw bale builders or helpers is decreasing but also the workload during the post-processing of the wall increases massively. in a new building the bales can be infilled from inside, in wrapping also the plastering is carried out exclusively from the outside. So please do not save money on the wrong place. Additionally the construction site becomes much safer.

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SESSION PLAN S2

U4 – WRAPPING (EXTERIOR THERMAL INSULATION)

U4

Session Plan U4-S2: Construction Objectives: Trainees ... … know different structural options of wrapping and retrofitting and their characteristics and bale requirements. … know how to fix the bales, to stabilize the system and all the different techniques. … know the different options to compress the bales within the systems. … know the details of the connections: foundation, corners, windows, doors, roof etc. … know how to prepare the different surfaces for plastering.

Skills:

Execute wrapping and retrofitting construction methods Use of different compression and fixing techniques Organize and finish the work according to schedule Execute good connection details Knowledge of how to maintain integrity of the insulation Prepare different surfaces for plastering

Methods:

Practice

Theory

Practice on different wrapping and retroffiting systems Different structural options of wrapping and retrofitting and their characteristics and bale requirements Fixing the bales with different techniques Compressing bales within different systems Advantages and disadvantages of wrapping and retrofitting techniques Details of connections: foundation, corners, windows and doors, roof, etc.

Preparing different surfaces for plastering Study and develop a case-study comparing the results with other trainees.

Trainer:

Place:

Workshop or building-site and classroom

Duration: 5 days

Equipment:

Beamer (projector) Bales Structure or model to work on with tools

Documents:

Info sheets: I1 Wrapping I2 Retroffiting I3 Details Text sheets: X1 Wrapping X2 Retroffiting (Best building practice) Power point: P1 Ex. Wrapping P2 Ex. Retrofitting

Evaluation:

Multiple choice

Organization:

Preparation of a structure to be wrapped or retrofitted, preparation of a structure to demonstrate different construction details.

Order enough bales, prepare tools for measuring, cutting, adjusting bales, fixing, compressing.

Order all the material needed for preparing the plastering.

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Session Plan U4-S2: Construction

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INFO S2

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Session Plan U4-S2: Construction

INFO S2

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Session Plan U4-S2: Construction

007 CUT-Hybrid-Construction: centered - for direct plastering

If the surface of the straw bale wall is directly plastered, the posts (usually planks 2.5 x 1 5 cm are enough to hold the bales) are placed in the center. The back of our construction thus forms the wall of the old stock. The bale is simply pushed against the existing wall (on edge). If the wall is directly plastered, care must be taken when filling the bales to form a flat surface on the outer side (ie connect to the adjacent bales without gaps). In order to prevent the bales from slipping or falling out in hybrid constructions (where they are not clamped between the boards and the wall) they are fixed (nailed or screwed) after each row by battens (2.5 x 2.5 cm). Predrilling especially helps when the battens are nailed. This (5 m long) batten is entered in the bale (laid halm side) by cutting the straw on the surface with a bread knife or a wide, stable cutter. This additional 36 cm insulation (approx. 39 cm thickness incl. plaster) brings your house to low-energy standard. Alternatively, 26 cm miniballs can also be used (28.5 cm total thickness).

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Session Plan U4-S2: Construction

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008 CUT-Hybrid-Construction: outside - for (Timber-)Cladding

If the front of the bales is to be planked with diffusion-open boards (for example, for a ventilated wooden facade), we place the posts (2.5 x 1 5 cm or better 4 x 1 5 cm) flush with the front of the 6 cm thick wooden base. In this case, we do not need battens to fix the bales, since they are clamped between the wall and the boards (diffusion-open 1 6 mm DWD). If the wall is slightly sloped, our Wrapping wall should also be slightly sloped, just like in the assembly of a insulation composite system, which is usually not levelled. Otherwise, it must also be stuffed after each row, since crevices in the dewpoint area lead to convection and thus condensation. Please check the exact bale thickness before installing the hybrid posts, there are also bales which differ by the standard size 36 cm (about 34 cm thick). The bale density does not have to be as high (from 85 kg / m3) as with direct plasters (100 kg) and when stuffing, it is enough to fill the holes just in such a way that holes disappear, the straw doesn#t have to be well anchored. Contrary to the direct plaster, since the boards also hold loose straw. However, overhanging straw should be cut off, especially along the stands (hedge trimmer), so that the straw does not slide between the post and the board during assembly. Since here the individual rows are not fixed with battens (which also fix the distance of the stands), it is important to ensure that the posts / planks do not bend during the filling (especially at the corners). And it is advisable to fix the stands at least after each storey (2,5-3 m) on the wall.

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Session Plan U4-S2: Construction

009 Binding Straw Bales on the Wall Before the CUT hybrid construction was invented and adapted for wrapping, bales were attached to the walls with cords. New connecting cords were knotted on the two bale cords and these were then fixed to the wall (dowels and eyelets). This does not just sound like a lot of work, it is. In addition, there are other disadvantages of this (outdated) technique: the cords intersect the bales and deform them, fixing dowels in old walls can be a real challenge, the strings remain as in the load bearing straw bale technique on the bale, which makes shaving much harder (or impossible).

The first layer of bales is attached to the base plate with small spikes (also as in loadbearing straw bale construction). Pointed 2.5 x 2.5 cm battens with a length of approx. 20 cm fit into a 3 cm drill hole in base wood, to prevent bales from slipping.

The advantage of this technique (some argue with the continuous insulation area) is not clear on closer inspection, since hybrid posts (1 " planks) affect the total insulation value of the wall far less than e.g. remaining cavities, which are then filled with clay or COB or lime plaster. Of course, no "planking" for a wooden facade can be attached to this "construction", it can only be "plastered" directly. The technique is a mixture with or, rather, a relic of load bearing straw bale building, where bales have still been laid flat (47 - 50 cm bale thickness). Since we know that flat bales have a way worse insulation value than bales on edge, this technique is actually superfluous (unless wood is not available).

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Session Plan U4-S2: Construction

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010 Down-spanning Straw Bales in the Wall

The down-spanning of straw bales also comes from load-bearing construction technology. Admittedly, it compresses the bales quite good, thus closing up fairly reliably gaps between the bale rows. The packaging tapes, which are used for this purpose and are clamped with a packing tong, remain in the wall and - similar to the cords (tip 09) - are a hindrance when shaving the walls. Also the wood consumption does not really decrease compared to the CUT technique, because instead of the stands a massive, at least 6 cm thick and 36 cm wide, wooden top plate hinders the bales before constriction. As well the base plate has to be doubled so that the tape can be pulled through. And again, the wrapping tapes are guided through eyelets, which are fastened to the old stock wall every 50 - 100 cm. In the case of bad bales, this technique may have advantages due to the stronger compression with the packaging tong (and possibly precompression with truck straps). In case of good bales, the technique as well as the binding with cords to the wall (tip 009) is actually only one big disadvantage compared to hybrid CUT construction.

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Session Plan U4-S2: Construction

011 Straw Bales spanned to the Wall

Jakub Wihan, the Czech strawball builder, who has worked with amazonnails for a long time, is the inventor of this optimized fixing technique, which is still used today in Slovakia (Boris Hoechel demonstrates the technique). Bbales are installed here again on edge, after the second row, a wrapping tape is placed on the straw bales and guided through two eyelets attached to the wall. On the front, 2 strips or round wood are threaded through the cords and formed into an "H" with an approx. 50 cm wide spacing board. As soon as further rows of bales have been piled up, the wrapping tapes are now pulled over the "H" connected to the eyelets of the back wall. This H auxiliary construction presses the bales towards the wall, with sufficient tension (and not too hard bales) the wood pulls into the straw bales and forms a straight surface at the front. The advantage of this technique is that the bales are attached to the wall with pressure (tension), exactly what we mean by fixing the bales to the existing wall. And the technique is relatively fast, you only need 2 eyelets per "H" and can simultaneously clamp 6-9 bales on the wall. But once again, the disadvantages of this technique are: the durable fixation depends on the 2 eyelets, if they are not well anchored, the entire bale wall falls, as well as if the wrapping band tears. Also here the strings remain on the bale and hinder shaving.

Finally, at least the board must be provided with a plaster ground.

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Session Plan U4-S2: Construction

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01 2 Straw Flakes for thinner Layers mounted with Pallettes

Used pallets are a favorable construction material, usually cheaper than the wood in it. In addition, we do not need Euro pallets for this technology, but the more favorable pallets with a little more space between the boards at the top. These can be filled well with bale flakes while lying backwards on the ground. Afterwards, the filled and "insulated" pallets are simply screwed to the wall, thus compressing the protruding bales again compactly. From the front (visible) cavities can be re-stuffed (therefore also the slightly larger distance between the boards is ideal). In the spaces we fill clay with a lot of straw fibers (COB), which sucks the moisture from our dewpoint area, since clay is strongly hygroscopic (water-absorbing). As with a diagonal bracing, it must be covered with reed stucco or another plaster carrier. The advantage of this technique is that it can achieve lower insulation thicknesses up from 1 5 cm (pallet thickness). Depending on the distance between the wall and the pallet, the insulation thickness can be set individually. Pallets are solidly built, even if a nail is missing or riddled, it doen't fall apart. Who once tried to break a pallet, knows how stable they are. This technology is also extremely favorable at around â‚Ź 10, - / m2 of material requirements (wooden stands, pallet, straw). By the way, we do not fix the pallets directly on the wall, but on planks which are connected between base plate and the roof by a distance of the width of the pallets (for example 1 25 cm), like our CUT posts.

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Session Plan U4-S2: Construction

01 3 Straw Flakes for thinner Layers: building a Cage

As already mentioned for the pallet wrapping technique (tip 01 2), we need a kind of cage for thinner insulation thicknesses below 26 cm (mini bales) or 36 cm (standard bales) in order to fix the bale flakes. The thickness can thus be individually adjusted from about 6 cm (for example, if the roof overhang is not sufficient for whole bales).

In order to fill the bales as efficiently as possible, post distances of 36 cm, 47 - 50 cm or 72 cm are ideal.

Materials which are suitable for a cage: 1 ) diffusion-open boards (DWD), see also tip 025 form a wind-tight outer plane, and are especially useful when a wooden facade is to be mounted (price for DWD around â‚Ź 8, - / m2). See picture above.

2) 2.5 x 2.5 cm strips/battens at intervals of max. 10 cm have the advantage that they can be directly plastered with appropriate plaster thicknesses (2-3 cm) without plaster grounds (but with mesh). The advantage here is, as with the pallets, the filling of the interspaces with clay (when plastered with lime directly on top, we use 5-6 parts of clay and 1 part of lime) thus keeping our straw insulation layer dry as with Fachwerk-houses. See picture on the left.

3) It is also possible to use bamboo, (reed) mats or similar solid materials, depending on the regional availability.

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Session Plan U4-S2: Construction

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01 4 Break between Perimeter- and Wall Plaster: Dripping Nose

To prevent moisture transport from the cement plaster in the splash water area (30 cm above ground level) up to the lime plaster facade, these two plasters must be separated by a horizontal barrier. This droplet is essentially an extension of the horizontal barrier between the strip foundation and the base plate of the construction to the outside, in such a way that water can drip off (picture above left).

The dripping nose is at the same time the stiffening of this metal strip. Ideally, better use zinc, aluminum or stainless steel instead of galvanized sheet, which is a few euro cheaper but not permanently rustproof, if it is not painted. The drip can be fixed on the outside of the base plate (with roofing nails) or under the foot threshold. It then stands horizontally to the outside (plaster thickness + 5 mm overhang) and then bends obliquely downwards to the dripped nose. Each tinsmith will bend such a sheet in short time in the desired length. A 5 cm strip of Steico Underfloor can be clamped above the metal (picture on the upper right). A further possibility is to cover the entire base in the splash area with metal, the drip nose is then just above ground level (Center).

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Session Plan U4-S2: Construction

01 5 Direct plaster on Straw Bales: rainproof and windproof

Straw surfaces - properly prepared - are excellent plaster carriers. For this purpose, straw bales must be well baled (or compressed) to a minimum density of 100 kg / m3. The surfaces must be shaved ad levelled with the hedge trimmer and hollow spaces should be filled with as long straw as possible. It is not advisable to store the straw bales for month or years (so that the smooth but protective wax layer disappears). The surface - after shaving - is so rough that the clay and lime plasters hold on to this plaster carrier (the straw is shaved / cut off with the hedge trimmer with strong pressure). Excessed wood parts wider than 2 cm must be covered with plaster grounds (such as reed stucco, Steico Unerfloor, soft fiber board, Heraklith BM or cork) or heavily roughened (every 3 cm). Connections to window frames, doors, roundwood stands, etc. must be air- and wind-tight (tapes, apu strips, multiple plastering). Because earth- and lime plasters leadeasily to rust in metals, metals in touch with plasters must remain permanently rust-free (stainless steel, zinc, aluminum).

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01 6 Timber Cladding on Straw Bales: Boards and Ventilation Areas

The safest method of protecting straw from rain and moisture is a wooden facade.

Since wood with a μ-value of > 20 (spruce dry 50, damp 20) has a moisture-braking effect, a back-ventilation is to be provided, which allows the moisture from the room air diffuse outwards. In the case of vertical ventilation areas, 3-5 cm are sufficient, horizontal ventilation areas (flat roof) should be 8-10 cm. They are usually built with battens and counter battens, so that the air can sweep from all sides through the ventilation area. The first lattice is always installed in the direction of the boards / planks of the wooden facade, the second is then 90 ° to it. In order for air to circulate (which practically always works by the solar radiation on the façade when the air is heated), an air inlet of at least 3 cm in width at the lower end of the wooden façade and an equally wide air outlet at the upper end has to be installed. This openings are covered with a bird protection mesh (picture on the upper right), so that no animals (eg wasps) can enter here, this perforated mesh should be relatively fine (2-3 mm).

The second layer of rain protection underneath the façade then usually forms a diffusion-free, but also water-repellent, wind-proof layer: this is usually achieved with diffusion-open panels (DWD) or with a two-layered clay plaster: the second (fine plaster) layer closes the cracks of the base plaster. In order to be windproof even under the battens, it is advisable to plaster the clay over the entire area and to install the battens afterwards.

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Session Plan U4-S2: Construction

017 ventilated Glass Facades in front of Straw Bales: visible Straw Building physics says that a (not wind-tight) insulation layer, which is not enclosed (ie aerated), loses its thermal properties. The estimates range from half to 100%.

Therefore an unplastered or unplanked straw bale house should not insulate at all (which is easy to check, anyone who has once built such a house knows how fast it can be warm, but it can cool down quickly when the insulation area is ventilated).

But if the wind is hindered by a glass or Plexiglass layer (of course glass must also be ventilated, so cold air flows into the ventilation area), and according to calculations of the house of the future project "Biohof Achleitner" (20 m-long straw bale wall behind glass), the heat gain in this "glass house" is greater than the loss due to the lack of wind resistance: U-value: 0.11 4 W / m2K (plastered: 0.11 6 W / m2K).

Maybe this is right for the south side ... Nevertheless, such techniques (similar to bottle walls) are at least to be questioned: for sure they serve more aesthetics than building physics.

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Session Plan U4-S2: Construction

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Sarah Wigglesworth´architectural office in London / Guest House in Chile, AATA Arch.

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SESSION PLAN S3

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Session Plan U4-S3: Prefab Wrapping Constructions Objectives: Trainees ... … know the tools and machines used on the straw bale building site. … know specific problems of straw bale building site organization. … know how to solve any technical problem conveniently. … know accident prevention regulations, how to recognize dangers and save working practices.

Skills:

Handling tools and machines which are used in straw bale construction

U4

Trainer:

Place:

Workshop or building site

Duration: 4 hours

Equipment: Tools

Methods:

Demonstration Explanations Practice

Theory

Specific problems of straw bale building site organization

Practice

Trying the tools, visiting building site

Documents:

Info sheets: I1 Tools I2 Building site Text sheets: X1 Tools X2 Building site Power point: P1 Tools

Evaluation:

Multiple choice

Organization:

Looking for an appropiate building-site in the surroundings; prepare different tools and materials for the demonstration

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Session Plan U4-S3: Prefab Wrapping Constructions

018

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system/haus/bau-Module, entwickelt von C. Kastner, H. Gruber, W. Schmelz

INFO &TIPPS S3

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INFO &TIPPS S3

Session Plan U4-S3: Prefab Wrapping Constructions

019

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Jules Ferry Residence in St. Die des Vosges (FR) von Bet Gaujard Arch.: 7stöckiger Bau

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INFO &TIPPS S3

Session Plan U4-S3: Prefab Wrapping Constructions

Jules Ferry Residence in St. Die des Vosges (FR) by Bet Gaujard Arch.: 7storey-building

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Session Plan U4-S3: Prefab Wrapping Constructions

020

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Complemedis AG, CH: Wrapping with prefabricated modules by Werner Schmidt

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Session Plan U4-S3: Prefab Wrapping Constructions

021 022

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Straw/Reed-Facade by Kengo Kuma, Japan; below: Waseda University Students have developed this prototype: Straw cools through evaporation in summer and heats through fermentation in winter

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U4 – WRAPPING (EXTERIOR THERMAL INSULATION)

INFO &TIPPS S3

Session Plan U4-S3: Prefab Wrapping Constructions

023 024

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Enterprise Centre/University East Anglia, UK; Schelfbauhütte in the Alte Brauerei, DE

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Session Plan U4-S3: Prefab Wrapping Constructions

025

School in Issy les Moulineux and Montreuil, FR: external mounted straw bale modules

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INFO &TIPPS S3

Session Plan U4-S3: Prefab Wrapping Constructions

026

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MakeYour City Smart Project by Paul Adrian Schulz: conccrete slab building with DIYstraw bale walls: social living in Vienna (Partner: ASBN); ASBN-Projec InsulateGreece with a similar idea against Fuel Poverty, GR

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Session Plan U4-S3: Prefab Wrapping Constructions

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INFO &TIPPS S3

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INFO &TIPPS S3

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Session Plan U4-S3: Prefab Wrapping Constructions

MakeYour City Smart Projekt-Calculation for the project by Paul Adrian Schulz: Materials and Work in Straw Bale Walls +/- Self-Building (DIY)

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Session Plan U4-S4: Alternatives: Straw Injection-Systems

INFO S4

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027

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Session Plan U4-S4: Alternatives: Straw Mats

028

INFO S4

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Session Plan U4-S4: Alternatives: Reed-Mats

INFO S4

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029 A) 25 cm Reed (5 Layers)

U-Value: 0,208

W/m 2K

PEI n.r.: >1 7 kWh/m² € 52,50 - 75,80/m2

B) Straw, Reed-Insulation-Board, Lime-Direct Pl. 26 cm Straw, 5 cm Reed Mat, complete 33,5 cm Wrapping-System: Material Price/m2 (AT) Straw Bales: around € 8,00 - 11 ,20/m2 (cert.)

Constr. with/out window box: € 1 3,05 - 36,50/m2 Reed insulation board (bauschilf.at): 8,47/m2 Lime Plaster 2,5 cm, Mesh: € 8,70/m2 Material - complete price: € 38,22 - 56,17/m2

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STEP – Straw Bale Training for European Professionals UNIT 4 – Wrapping (201 7) ©/Editor/Texts/Tipps: Herbert Gruber (ASBN) Co-Workers: Helmuth Santler, BuildStrawPro-Team (Erasmus+ Projekt) Design & Photos: Herbert Gruber; more Photos: Naporo (8) Hagebau (8), u-wert.net (9), Geocell (1 5, 1 6), Misapor, Kurkfabriek (1 5), Horst Danner, GrAT (22), Virko Kade (23), Kengo Kuma (36), Icons: Michael Howlett (SBUK) This Handbook bases on the Handbook by the LeonardoGroup STEP (201 5)