I am totally new to cob. I have read about it, looked with longing at loads of images, but never tried it.
Well never, I did try to patch a cob wall in the one room of the old house I am refurbing in Bulgaria, and it has cracked and looks like a dried up old river bed!
Cob is traditional here, and when i knocked off some cob plaster work over stones in the room because it was falling off ( due to water ingress) I was amazed to find grass seeds, chicken bones and rose cuttings all mixed in with the clay!
Anyway, I digress.
I have a large barn attached to the house, and I would love to convert it into my kitchen. The worries I have are, to name a few :-
1 - there seems to be a lot of rising damp under the stone floor, which even creeps into the house which is approx 1 foot lower than the barn floor. Other than digging a major water drainage ditch outside of the barn approx 1/2 meter off the foundations, I am not sure how to combat the water. Ripping the stone floor up and laying plastic sheeting seems an option, but I still think the water will be coming up under the plastic and into the house.
2 - the outside of the barn frontage is stone paved. The idea is to enclose the front of the barn with a low cob wall and lots of windows for light. How deep do I need to make the foundations for this cob and window wall, please? It is not load bearing, as the barn structure does all of that ( I think !)
3 - How on earth do I key the new frontage into the existing stone walls of the barn and house.
Bearing in mind this is Bulgaria, and the house is approx 100 yrs old from what I understand. Foundations were not a big thing in those days it would seem. Definately they did not know about damp proofing!
The land is clay, and there has been quite a bit of settling / shifting as nothing is square, in fact things lean quite a bit downhill!
My concern of digging close to existing foundations is that I could cause even more upset and shifting. In which case I will have to make a new plan regards converting the old barn into my kitchen area.
A few images attached..
Any opinions, thoughts and suggestions most welcome!
Really cool building. This is tough for some of us, I have no clue what the weather conditions are like in your area--how much freezing weather or how much precipitation do you get throughout the year? If your moisture and freezing are lower you won't need a real deep foundation. I would do a shallow rubble trench foundation but protected with some insulation on the outside wall of the foundation--again, this is only if you have freezing weather.
If there is a lot of head space in the barn, maybe you don't need to rip out the old floor but build up instead. Consider doing a new layer of drainage followed up with plastic and then a new floor if you have room to spare. You would have to make a sort of step up into this space if you did it that way, but it would require a lot less work than ripping up stone.
Hi Daniel, and thanks for the reply.
Yup - its a cool building with lots of quirks and surprises. The old wine cellar is still there in the back of this barn, with a sloped floor and small channel to handle the spillage from wine making!
Bulgaria gets cold, winter can easily see -25 deg C and the frost line is approx 60cm where I am, in the foothills of the mountains.
Rainfall can be heavy and frequent as well.
I am in the middle of sorting out a badly designed water flow around the house, where they have a stone lined channel feeding water TO the house instead of away and it flows onto the paving in front of the barn, and then into a pipe laid under the stone floor across the barn and out the back of the barn.!!!
Why - will never know.
So I am laying a new channel above and behind the barn diverting surface water from the hill across the side and back of the barn instead in front of it. That should help, as intend on laying it a good meter, to meter and half.
I figured it would need to be that deep to get to approx the floor level of the house, so run-off as well as seepage is diverted away from the property.
Don't let all that grass fool you, its popped up between the massive stone flag paves that are laid out there. It has since mostly been cleared, but currently covered with snow so used the old pic to show you..
Head room in the barn will not be great afraid, as the massive old oak beams run through the house and into the barn - actually they are whole trees.
Currently there is a height difference between the barn floor and the house floor of approx 15 / 20cm with the barn being higher.
The stone wall you can see is the original root cellar, currently a temp kitchen.
Sadly there is a lot of damp in there, as they laid a cement floor over the mud, and because it is lower than the barn as well, so water from behind the house up the hill seeps under the barn, under the stone paving, and into the cellar..
So I guess I am looking at deep foundations - how deep considering a 60cm frost line?
What kind of insulation - just a plastic wrap on the outside of the foundation - and how high up above ground level should I carry the plastic?
And the biggie - how do I key the new wall covering the front to the sides of the barn and house.
I can't comment on cob because I've never worked with it.
I would suggest that for foundation drainage your best solution is to excavate around the perimeter of the building and install 4"perforated pipe at the depth of the footings (if they exist), or at least to a depth beneath the floor level. Once the excavation is open you may opt to put 2"rigid insulation covered by adhesive waterproofing. There are many products available like this here in the US, I don't know what may be available to you in Bulgaria. Once the foundation is waterproofed, you should backfill with gravel or small stone, not earth, up to finished grade level.
The uphill drain you plan to install to a depth of 1.5 meters will help a lot. Make sure you backfill with gravel or small stone.
The downside to installing a perimeter drain on an old foundation is that it is very expensive. The only other option is to install a sump pump inside the building. Dig a pit about 3feet deep and 2feet wide, install a plastic garbage can with perforations to allow water infiltration then a sump pump into the pit. This will keep the space just barely OK. It's not a good solution, but it is the cheapest.
posted 3 years ago
Thanks for the input.
I was wondering, how far from the edge of the building would I excavate?
I am worried that they did not use good foundations, the house is around 100 years old, and build on clay.
would hate to disturb things so that i start getting a weakening of the foundation soil and it then starts to slip.
for the most part the house and barn are built of stone, so very heavy.
The top floor of the house is cob, as is the frontage.
The top of the barn is wood panels in the front, and cob bricks at the back.
That is one of the reasons I was thinking of digging away from the building instead of close to it, simply because I don't know how far away from the building would be safe without causing problems.
But I like the idea of a trench around the perimeter closer to t he house as it would be more effective.
attached some pics of the land and how steep it is.