The earth plaster walls (and why Dave went quiet for a while)

Hi everyone, sorry to have been so quiet for the last month or so, I think the whole project was starting to wear me down a bit towards the end of last year, and we have had quite a lot of problems with our internal walls. Between that and christmas I’m afraid I couldn’t really face the blog.

But, the decorations have come down, its a new year, and I think its about time I told everyone what has been going on at Speckled Wood.

The internal partition walls of the building are of a lath and plaster construction. The plan (and and awful lot of work went into it) was to use earth plaster on these walls.

I remember, as it turned out rather foolishly, a remark being made just before we started plastering over our hand cleaved chestnut laths. It was something along the lines of not expecting them to see the light of day again for about a hundred years or so.

As it turned out nothing could have been further from the truth. The laths were visible again all too soon.

We have been really lucky that so many people have been prepared to come and help on the project, that is part of the reason I have been dreading having to write this post. I don’t know how many people helped us with the earth plaster, but there were a lot.

It was mucky work, but everyone got stuck in, and for a while it looked like it was going really well. But soon we started to have problems. The plaster was crazing, cracking and starting to delaminate from the laths. Every week we put in at least two days work filling cracks, wetting the plaster down, putting on extra slip coats, and readhering it onto the laths.

You can see some of this process taking place in the picture above. Several times chunks of plaster were so much on the verge of falling away we had to tear them off and patch in with new clay.

We all put so much effort into it but the cracks kept on appearing…

We managed to get to a stage where they were getting smaller over time, but still we were having problems getting it to adhere properly to the walls. We put a heap of work in just before christmas, had some time off to recover and then came back in early January to see what on earth we were going to do.

I tore off a couple of the worst chunks to have a look at what was going on underneath, so that we could make an informed decision.

Underneath it was bad news. We really wanted to stick at it, give it a few more weeks, presevere and make it work. But I was worried. We were going to have to re patch so much of it we wouldn’t be back to where we were for a month or so at least. It just takes for ever to dry, and you have to be carefull not to let it dry to quick or the cracking gets worse. Then came the final, and biggest worry. After all that extra work we were considering putting in, was there any guarantee we would manage to finally get it working? In the end I realised, we could put in a solid months work and still fail. We had to call it a day, cut our losses, and find a different way forward. The earth plaster had to go.

It was funny really, I had been dreading it for ages, and fealt absolutely awful about it (very much feeling I have let people down by not getting it right) but when the decision was made I just knew it was for the best. We are now in the process of tearing off all of the clay and we will be lime plastering the internal walls instead.

One thing is for sure, it certainly comes off a lot easier than it goes on.

I know some of you reading this are probably far more expert in these things than me, and some of you probably know where we went wrong. I think I know some of the reasons, and am sure 3 or 4 mistakes conspired together so that in the end we were fighting a losing battle. I am pretty gutted about the whole thing, it was one of the aspects of the build I really wanted us to get right. But, I also know that we are building a house, and can hardly call it that until it is in a fit state for someone to live in. The time really has come to get back to the bigger picture and stop staring at cracked mud.

Lime plaster should work fine as a replacement, in terms of the history of architecture you could probably argue we have taken an evolutionary step forwards! I know it is the right choice for us, with what we have learnt I wouldn’t be afraid to try it again, but it would be on a much smaller scale, and only for feature areas, I have been converted to the joys of lime.

I guess I was wrong about how soon those laths would be on display again, lets hope next time they are covered over its for good.

Its been quite cathartic writing this, I really hope nobody out there is too dissapointed with our decision. I really hope it means I can get back into the blog, as well as back into the project, there is so much there that is going well, hopefully I will be bringing you news of some of that over the next few weeks. Happy New Year!

 

 

Mud Wrestling

Was just wondering if a post title like that would generate any extra hits from the search engines…

The inside walls of the Speckled Wood building are going to be of a lath and plaster construction. We started nailing on the laths a while ago and last week we started to do the earth plastering. Its a pretty messy job, but good fun.

Way back when we dug the foundation pits for the building we saved the clay we found in the bottom of these pits. This is now in the process of going back into the house to create the walls, rather neat and circular I think.

Some of our clay was put onto a tarpaulin on a level patch at the back of the building and some water was poured on. We then set to work on puddling, or trampling, the clay.

Its a childs dream, squishing about in mud and getting absolutely covered in the stuff. You just can’t help laughing while you are doing it.

Sand and straw, again recycled from the rest of the build are added to make a mixture that will be more stable as it dries on the walls. This is trampled into the mix and the whole lot is turned over several times by rolling it in the tarp.

Any stones we found were removed from the mix and placed in the hedge and gradually after half an hour or so of slipping, laughing, chucking the odd sod of clay at people, trampling and mixing a texture was arrived at which was deemed to be just right for daubing onto the walls.

This was then barrowed inside for us to start on the actual plastering. There were no trowels being used here, the mix is picked up in your hands squished about to check there are no stones and make it pliable before you slap it onto the wall.

The idea is to try and press it on so it just pokes through the gaps in the laths and hooks over the top of them to hold itself in place. It was really satisfying work, the plaster is smoothed out as you go and gets a wonderful texture from all of the hand prints in it.

I had thought it would be abbrasive on your hands, but nothing could be further from the truth, it was actually really gentle. After you have finished and washed your hands you find they have never been so clean.

Two “slip coats” of fine loose clay will be appled later to create a finer finish, but I think the wall already looks great. Its is gradually changing colour as it dries out, and I can confirm from the mud that dried under my fingernails that when it is dry it will be a sort of fawny light brown colour.

The laths start going on

Such a beautiful day here today, a real indian summer day, lots of sunshine and the start of all the colours coming through in the trees. When I got in this morning the sun was shining through the mist and the dew on the spiders webs. As the air warmed the spiders seemed to sense something and decided it was the right day to start ballooning. This is the term for the way their young disperse on certain days in september and october. Lots of spider species do it, and its a pretty clever evolutionary trick. They make their way to the tops of the trees and bushes, spin a length of silk and let it get caught in the breeze. The silk carries them away into the air and they float off to populate new areas. They can be carried for many miles, and have been recorded right out at sea. But what you tend to notice is the way the breeze often blows them together and the strands hang in groups across the trees. Lots of them had been making there way across Swan Barn Farm and quite a few had landed in the oak tree next to the new building.

On the inside of the building today we started putting in some of the chestnut laths on our internal walls. The picture below shows the patch of coppice we cut last winter for the timber frame of the building, this woodland also provided the timber to make the laths.

Laths are horizontal strips of wood which are nailed across panels prior to being covered with plaster. They provide the structure and the plaster that binds onto them provides the finish. We will be using earth plaster, more on that later.

The laths were made for us by Justin, a local coppice worker who makes his living in the woods around Haslemere. Along with a number of other products his team cut a series of four foot lengths out of the timber that they felled last winter, these lengths were then split into blanks and the laths were cleaved off the blanks.

A froe is used for the cleaving process, this clever tool can be steered through the grain of the wood to ensure you get a nice straight even lath (after you have learned how to use it well).

A billhook is then used to trim up any rough edges.

Prior to bundling them up for delivery.

Sweet chestnut is a naturally durable hardwood, meaning they should last well, they came from a coppice so they have been grown in a sustainable and renewable manner. Finally, cleaving them by hand rather than sawing provides the ideal surface for the earth plaster to bind onto, all in all the ideal material for our walls, and the whole process took place within a stones throw of the building.

The internal walls of the new building are made of a sawn sowftwood stud frame onto which we today started nailing laths. The interior of the walls will be filled with sheepswool insulation. They are positioned so the plaster will cover them as well as sneaking through the gaps in between and binding around the back of them.

We are using copper nails, as the tannins in the wood would attack steel nails and damage them. With the colours of the copper nails and the grain showing in the sweet chestnut it makes a pretty attractive looking wall, it almost seems a shame to plaster over it.