LimeWords
June Issue 2015
LimeWords Welcome to LimeWords, a new quarterly magazine produced by Heritage Cob & Lime.
I N S I D E T H I S I S S U E
Differences Between Lime Mortar & NHL
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Using Lime Today
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Rising Damp
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Reader’s Stories
To Tank or not to Tank
If you have a question about traditional building methods, or would like to feature in our Reader’s Stories, then please get in touch by email: mail@heritagecobandlime. com
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The purpose of this magazine is to bring you tips and tricks on using lime mortar, some do’s & don’ts, customer stories, and all sorts of snippets that we hope you will find useful.
using lime based mortars that allow buildings to breathe. LimeWords will feature a variety of traditional building techniques, including thatching, stained glass, carpentry,
ed Woody Hudson of Hudson Stained Glass, who designs and repairs stained glass or specialist stonework of Ben Martin of Martins Stonemasonry.
Articles won’t be solely about lime mortar of course, we also share info on cob, and how to look after your cob property for generations to come. Whether your property is constructed of cob, stone rubble, bricks, or a mixture of all of the above then this magazine will help guide you to understanding how your property was built and the best way to maintain it. We will talk about damp issues in old buildings and how they can be rectified by
stone work, and all related subjects. Over the coming year, we shall be inviting contributions from specialists in some of the subjects where they are outside our own area of expertise such as the talent-
Our aim is to enhance your enjoyment of your traditional property through understanding and knowledge about how is was built, the products that were used and how to ensure that the building remains in a healthy state.
F e a t u r e o n t h e F r o n t P a g e o u r 2 0 1 6 C a l e n d a r We love to see photos of our customers work and we know you are interested as well. That’s why we are running a photographic competition with a difference this year. Anyone can send up to 3 photographs of their restoration work, preferably with a couple of lines explaining
how and what they did, and the winner will feature on the front cover of our calendar 2016 and win a £50 voucher to spend with Heritage Cob and Lime. Runners up will have their photos featured through the rest of the calendar. Closing date for entries: 30th September 2015.
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Please email your images as jpegs to: mail@heritagecobandlime. com
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L i m e W o r d s
W h a t ’ s
t h e d i f f e r e n c e b e t w e e n m o r t a r a n d N H L ?
We often get asked by customers, “ What is the difference between lime mortar and NHL?” Lime Mortar is known by several names: Lime Mortar, Fatty Lime Mortar, NonHydraulic Lime Mortar and Putty Lime Mortar. It sets by carbonisation, is a breathable mortar and can be lime washed. We have a wide choice of lime wash colours available. NHL (Natural Hydraulic
Lime) sets in water and does not have the same breathability or flexibility as fatty lime, however it is a useful lime based product.
NHL is available as a powder product
Where a property is situated in an exposed area, e.g. near the sea or where it receives the full brunt of the weather, NHL is very useful as it sets relatively quickly and gives a harder set. NHL will need to be painted with a mineral paint– we recommend Keim Paint.
Did you know that lime mortar is one of the oldest known types of mortar? It dates back to the 4th century BC and was widely used in Ancient Rome and Greece when it largely replaced the clay and gypsum mortars common to Ancient Egyptian construction U s i n g
Today, lime mortar is being recognized more and more for its ability to allow a building to breathe. It’s suitable for all types of buildings, from a modern barn conversion as shown in the picture on the right, to a Victorian town house or a 1930’s bungalow.
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Fatty lime mortar available 25kg, 750kg or 1 tonne
L i m e M o r t a r w a s u s e d e x t e n s i v e l y i n A n c i e n t R o m e
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Cob in particular must be allowed to breathe in order to maintain an optimum micro climate that is neither too wet or too dry. It’s always wonderful when customers ring us to ask about restoration a property using lime mortar. If in doubt, please ask, we are here to help.
T o d a y
L i m e W o r d s
R i s i n g
P a g e
D a m p ?
If you have bought an older property and someone tells you that you need to put in a damp course, please don’t! “But the walls have patches of mildew on them– we’ve got rising damp” we hear you cry. The reason for the damp issues is not because you haven’t got a damp proof course but more likely because the internal walls have been plastered in pink plaster and the outside walls rendered in cement mortar.
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remove all the hard mortars and replace with lime mortar and an appropriate lime wash, or if it’s internal paint you can use casein paint, then your house will be able to breathe. And guess what? The damp issues will be no more. We do also advocate that you always keep your gutters and downpipes clear, make sure your roof is sound and of course do the necessary maintenance that should be carried out throughout the year.
Whether it’s a cob house, brick, or stone and rubble construction, if you
Does and Don’t of Painting over Lime Mortar Use a breathable paint such as lime wash. It’s economical, can be made in almost any colour you wish and can be used on interior or exterior walls. For interior walls
only, casein paint or clay paint is also suitable. Avoid modern paints that seal the lime mortar. This will lead to damp and mildew issues such as in the picture opposite.
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The problem of rising damp is easily sorted.
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Reader’s Stories Our customers have some great stories to tell, all of them different, but what they do have in common is a passion for understanding how important it is to work with the fabric of the building. Nikki and Richard, who together with Nikki’s Mum and Dad, Pat and Alan, undertook quite a challenge when they bought a disused cob barn on the edge of Dartmoor. We caught up with Rich and Alan when we were first asked to visit the property just after they had bought it, and what a delightful property with a lot of potential to build a stunning home for the future.
The property nestles deep in a valley with access down several narrow lanes, some of which had grass growing up the middle. When we set eyes on the barn and the setting, we fell in love with it, just as its new owners did.
And so work began, with Richard and Alan making frequent trips down from their home in Essex to put all their spare time into making this space a great home.
Work was also taking shape inside, with large wooden French doors added at the far end of the barn to accent the light and space within. Nikki sent
Richard and Nikki had been searching for a long time to find the right project and here it was; an exciting, untouched barn, ripe for conversion, complete with a series of smaller barns, and a stream meandering through the property of this peaceful setting. The overall condition of the large barn was good, thanks in the main that it still had the original lime mortar on the wall that faced the weather, the tin roof was overall intact, and any repairs needed to the cob had been carried out using cob blocks. It was great to see Richard and Alan’s obvious enthusiasm as we talked them through the process of what they needed to do to maintain the fabric of the building in the best possible way.
by carbonisation, unlike cement which sets when water is added), the haired coat was added, followed by a smooth top coat.
A new roof replaced the ageing galvanised iron roof as per building regulations that stipulated the roof had to be replaced with like for like. The property received its first coat of fatty lime mortar, known as the scat coat. Once this had carbonated and dried (lime dries
photos to the Grand Design Show at Birmingham's NEC and was thrilled to be chosen to do a half hour initial consultation on stage with George Clarke. Well done Nikki, your family project is an inspiration to us all!
Tanking—Don’t get caught up in the spin We need a lie down in a darkened room to recover when people tell us they have damp issues on their internal walls and their builder has recommended tanking the wall to cure the problem. For those of you who are not familiar with the term, tanking is usually done in one of three ways– applying to the walls either liquid bitumen coating, cement based slurry or air gap membranes– not strictly ‘tanking’ in the same way as liquids – it is a dimpled plastic sheet fixed onto brick, stone, block or render with plastic plugs to form an air gap cavity. But it won’t cure the problem, in fact it will make it worse. All that tanking does is to send the damp further up the wall via capillary action, thus moving the damp issue from one part of the wall to another. It’s simple Science really when you think about it. So what is the answer? Well it’s quite straightforward – remove any pre-existing cement or pink plaster, wood cladding or any other covering from the wall and take it back to the original surface underneath. This will usually be stone or brick. Pic opposite shows lime mortar—sorts out the damp issues
Next scat the wall with a soupy 3/1 fatty lime mortar mix, and leave to carbonate and cure– it will be white in appearance once cured. Next add a haired scratch coat, again leave to dry and carbonate, and then apply a smooth topcoat of 3/1 fatty lime mortar. If you want a really smooth finish, you can apply Heritage 3/2 fine skim once the top coat is dry. Finish with lime wash or use a breathable casein milk paint in the colour of your choice. What you now have is a surface that can breathe and wick away any excess moisture from deep within the wall. You should also remove any cement mortar from the exterior of the wall and replace with lime mortar. Don’t be caught out by the spin surrounding tanking– it’s to be avoided.