Renovating the Tiny House - A detailed look at sourcing and using lime/hemp & lime/linen mortars for wall-covering and insulation.

The Cream of the Crop: Lovely Linen and Lime.

Understanding the material

Like all organic matter linen and hemp react to their environment so although there are some indications as to the quantities used to make up plaster, there are no actual hard and fast rules. When making up your mortar consideration should be made for several factors.

The moisture content in the air on the day you are using the plaster.

The air temperature both inside and outside.

The movement of air both inside and out.

The particular batch of linen/hemp (I have never found two the same).

The grade of linen/hemp used. (see paragraph below)

The grade and type of lime used. (see below)

If you think this sounds complicated, it isn't. It is something you get to know instinctively the more you work with natural materials. If I can make an analogy, I might think of eggs. Most people, who don't keep hens, think that eggs come in uniform sizes, they don't, they just get graded that way commercially but on average a standard egg weighs 65g. Therefore in our case when we use our bantam eggs we weigh the eggs.

As a general rule these are the measurements we use:

For Hemp:
6kg lime
1kg hemp
6 litres water
Coverage about 1m² at approx 2cm thickness on an uneven wall

For Linen:
6kg lime
1kg linen
6 litres water
Coverage between 0.7 - 0.75m² at approx 1.5cm thickness on an uneven wall

Grades of fibres - Going green without getting into the Red

You can find ecological wall covering, which is not designated as such, sold at a much cheaper price than that at a special Ecological Builders' Merchants. For example, the hemp we used was actually organic hemp mulch, sold mainly for organic horticulture. The linen was  baled and sold for using in horse boxes. Our house is an old vernacular 18th Century farm and these grades of finish suit it. If you are thinking about your budget and using these materials in a less rural setting, then you can still economise by just using the finer grade of these materials as a final coat. As with most things it pays to shop around. The price of ecological materials is ever changing, as more farmers grow organic linen and hemp and as more people buy and use it, the price will begin to drop. In France the production of hemp is limited at the moment and thus the price, other than in mulch-grade, remains stable. However, when you consider that this is a one-off wall covering and that it is doing the double job of decoration and insulation and that above all it is giving you a healthy environment in which to live, it is worth paying the additional costs. Additionally if you are living in an old house, it overcomes the problem of what to do with the walls, which are often uneven and constructed of misshapen and unattractive stone. Furthermore, these stones were never meant to be seen but were yearly covered with a new coat of limewash. Houses like ours only ever had one window, a permanently lit fire, little through-draft and were kept even warmer by the sheer volume of life, both animal and human living within.

Lime

As already stated this house is of a vernacular rural nature and the 'roughcast' wall surface suits it admirably. We were doubly happy about this as neither of us wanted to use quicklime, which is dangerous stuff and makes a beautiful plaster, which keeps elastic for days and allows for the realisation of a smooth finish between batches. It was also used in the fine plastering on Church and manor walls to provide a surface ready for decoration with fresco. There is no reason not to use it if you feel confident about it but just be aware that it burns. 

There are various grades of hydraulic lime which are available and we found NHL 3.5 both easily obtainable and fit for purpose.

 

Preparation

In order to maximize the coverage of expensive linen or hemp lime mixture,  a lot can be saved by preparing the wall. This is also necessary for making a good solid surface for the plaster to adhere to. We firstly removed any loose materials between the stones of the Tiny House walls. This farm was built with clay and stone, clay being a very good natural insulation and mortar. We then pointed the joints with a lime mortar, made up of: six of sand to one of lime. We also rebuilt any of the areas which had lost stone, again thinking of costs, every bit helps!

Mixing and using the hemp or linen and lime plaster

Once we got used to the mix we used a cement mixer to make large batches of plaster but at the beginning we just mixed in a trug. Mix ingredients in this order: measured quantity of lime, slowly add water, mix in hemp or linen, leave to repose for approximately 10 minutes.

 

Just a small amount I mixed as a demonstration. Note the use of thick protective gloves, as even hydrated lime is extremely aggressive to the skin. When removing lime from the bag, we also wore eye protection and a mask. We also wore the same protective gear when using the cement mixer as it is easy to inhale lime dust at the beginning of the mix and get splashed by lime before the hemp or linen are thoroughly mixed together.

         Hard hats useful for low doors!      

For getting the plaster onto the wall you can simply use your hands, or alternatively a plasterer's float. To create the natural textured finish and also to retain the maximum insulation do not over-work the medium once it is on the wall. Hemp plaster needs more initial pressure to get it to adhere to the wall and is therefore much harder to work with than linen.

The walls of the Tiny House finished. Any lines where the different days' work shows can be smoothed down with a wire brush. For this reason never work to a straight edge because otherwise it is much more difficult to hide the join. This is the one drawback of using hydrated lime, it has a much quicker drying time than aerated and on a hot day can be drying as you work!

A final word about straw

When we first started thinking about renovating the main house we decided to start with what we had available. This was a large volume of straw, which had been left by the previous owner. Using a converted electric lawnmower, we cut the straw into short lengths and mixed it into the lime. Even after the first application on the North interior wall of the Kitchen (all we could get done before the onset of that Winter), we noticed an enormous difference in the warmth of the room. So if you can get hold of a suitable chopping machine and have access to organic straw, which at the moment here in France is 1 Euro a bale, it could make a very cheap and viable alternative to the above.

These plasters should not just be considered as purely wall insulation. Sue laid these floor tiles onto a 'raft' of linen and lime mixture, which in turn, we had laid on top of a gravel foundation. This insulated the floor and stopped the problem we had had with condensation forming on the previous concrete floor in the Summer. 


Renovation on our house is on-going, here is a film on some recent lime mortar pointing I did up on the workshop. Up being the operative word...



Thanks for dropping by and if you enjoyed this article, please fell free to share it and do ask if you need any further information.


All the best,
Andy

© Andy Colley 2013

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Re-roofing a tiny house including carpentry.

Would you be brave enough to buy this? No? Neither would we.

This is the start of a project which was forced upon us some ten years ago. We blame Napoléon. The Napoléonic Code for inheritance still holds good in France. It provides for all issue and states that you may not disinherit any of your children. It also means that your property must be divided equally. This can lead to some interesting anomalies and some pieces of property division are so obscure they are sometimes missed altogether when the sale takes place. We once met a guy, who only found out he actually owned the village football field when the greensmen turned up at his door to ask if they could start mowing the pitch for the beginning of the season.

Preamble - the background history to this project

Like many old vernacular Celtic houses ours is very hard to date. The oldest coin scratched up by the Chicks in the garden is a Louis XIII double tournois from 1615.

Looking back in time from the Bake House
We were told by a local historian, that the ancient granite arched doorway would have been taken from a nearby abbey during the Revolution. Under the Bourbon Restoration priests were sent out to scour the countryside looking for bits of looted architecture but this being at the back in an enclosed garden was no doubt overlooked.

Our little extra item, which doesn't even show on all of the deeds was a lovely little derelict 'Bake House' at the bottom of our garden. In the 19th Century our property was converted from a longère (longhouse farm) to a Post House. At that time it comprised, stables, offices, sleeping accommodation for postilions and a huge kitchen with a fireplace large enough to roast an ox. Our neighbours' house, comprised the Post House restaurant and two other neighbours' homes completed the complex, with the Blacksmith's House and the Forge. The land around which all this accommodation sits came with the property we bought and the little Bread Oven (below), which sadly had swapped its clay oven for some dilapidated rabbit hutches, was included in the deal.

This is what the little house looked like when we first bought the property. Very much in need of a little tender loving care. The house on the left was the Blacksmith's home later converted to two stories and in the distance the large red roof designates the much enlarged ancient Forge.

We had removed the long dead electrical installations and the rabbit sheds. Our time in France, in the ten years before we came to live here permanently, was always spent in and on the garden. Like most of the French, 75% of our day was lived outside, whatever the weather.

The tempest of 1999 destroyed a great raft of tiles, which came off like falling dominoes, all the way along the front of the main house.

These red, post-War terracotta horrors, which had replaced the original thatch, were now themselves recherché. The only emergency option we could come up with, was to remove and swap with those from the Bake House and totally re-tile the latter with new.

With the roof off and all the timbers removed the Bake House had almost disappeared. Now we had to put it back together again and in the right order.

Being in a hurricane was something neither of us had experienced before. The sound was incredible, like the TGV express train permanently rushing through the lane at the front of the house. Sue, having heard from her grandma that during the bombings of WWII, the whole family took shelter under the staircase, we decided it was the wisest choice. When the next morning we found part of the chimney had actually fallen through the roof into the stables we were really glad we did. I think it was not a good idea at the height of the storm, as we were drinking cocoa to the sound of the tiles being ripped from the roof, for me to suggest that we sung the theme tune to 'Titanic'. Actually we had neither of us seen the film but when Sue asked me what I thought we should do next, I'm afraid I couldn't resist.

Renovating a tiny house - an on-going project

Our main criteria for the job was to remove and preserve as many of the tiles as possible and to be really circumspect about the solidity of the old roof timbers. We'd always had a pretty good idea that the carpentry wasn't too brilliant but once we removed the tiles, we realised the full extent of the job. As you can see the main ridge beam was actually split along its length and was sagging. It was, in fact, being held together with a chain twisted as a Spanish windlass, this 'temporary' repair had, by witness of the rust, been effected some many year before. So we ended up starting from scratch, just with the four very solid walls you see at the start of this post. I was happy my years in engineering would give me the grounding for calculating and accomplishing the carpentry work

.....but neither of us were too pleased about the rain...

Pointing the walls with a lime mortar mix requires protective gloves for the hands but the diver's mask and snorkel are entirely optional.

Our cheerful neighbour at the back, kept leaning through the hedge to suggest we demolish the whole lot but we loved this little house and thought it deserved some tlc. That said if we had seen a property like this for sale, we would never have had the courage to touch it, which just goes to show that you never know what you're capable of until you get forced into it. There was one really positive thing going for a job like this and I think it is one reason why so many people love working on tiny houses - low roof! We held on to this thought just until we got up there. We had forgotten that the neighbours' house on the far side of the tiny house was excavated out of the bank. We just didn't look that way too often!

One thing that was slightly worrying was the weight of the new tiles. When they were delivered and had to be moved to the back of the house, Sue found she couldn't carry them in their banded-together state of 6 tiles. In fact she started out only being able to carry a couple of individual tiles at a time. This would mean the job, when we actually came to the tiling, would take longer than we hoped because of the time getting tiles up onto the roof. However day by day she gradually became more and more accustomed to carrying them until when she came to start tiling she was actually carting them up bands in tact. For my part I had to steel myself into going up onto the roof, as I had acquired vertigo from swimming underwater. However, a good ear treatment of hydrogen peroxide and a knowledge that it was raining and that nobody else was going to do the work soon got me going. This is something that the  hurricane taught us, you really have to be prepared to take on every job yourself.

The ridge purlin was lifted into place with a ladder and supported with a rope from outside. Just as we were doing this our neighbour leaned through the hedge to suggest we had cut it too short. My how we laughed!

I cut the timber for the 'A' Frame, jointed and pre-assembled it on the ground, to ensure my measurements were correct! The frame was then dismantled and assembled piece by piece in situ.

There are no conventional foundations to any of these old houses. They are built directly onto bedrock with outer and inner faces of laid stone on clay 'mortar' and between them a 30 cms infill of clay and rubble. There was quite a bit of pointing to be done and a deal of stone work before we could seat in the wall plate. We used lime mortar throughout.

Rafters going on and stone work capped off at gable ends

The oh so happy feeling when you begin to get a cover back on the roof.

Laths being nailed in place.

Fitting a layer of roofing felt provides an additional waterproof barrier - very useful for future hurricanes!

A really good buy from a discount store was this tradesman's waistcoat I wore on the roof. It had pockets for nails and loops for tools.

The first one was the easiest! They had to be bedded into mortar and I was working off a roof ladder.

Finished.

A few years on....

..and the brash red tiles have mellowed

and the view from the Bake House door has changed too.

To be continued.......

If you have enjoyed this post and found it useful, feel free to share it, comment and ask questions.

All the best from Normandie,

Andy

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© Andy Colley 2014

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