What cement/concrete mix should I use to secure a stacked stone foundation?
The barn on my partitioned farm has a solid sill frame around the entire fifty-sixty meter circumference.
One could undoubtedly believe that the barn has stood for a hundred years, and the farm is of course at least from the 1800s, but renewed here and there over time.
What cement mix should be used to "fill in" the gaps between all the stones so the foundation becomes firm and stable?
I don't want to risk any cavities where I haven't got the filling in, or the mix itself causing the wall to expand/contract with cold or heat and risk shifting the barn's sills.
The barn on my partitioned farm has a solid sill frame around the entire fifty-sixty meter circumference.
One could undoubtedly believe that the barn has stood for a hundred years, and the farm is of course at least from the 1800s, but renewed here and there over time.
What cement mix should be used to "fill in" the gaps between all the stones so the foundation becomes firm and stable?
I don't want to risk any cavities where I haven't got the filling in, or the mix itself causing the wall to expand/contract with cold or heat and risk shifting the barn's sills.
Such a foundation will never become stable by trying to mortar the inside and outside, nor by pouring concrete between the stones. The stones are of different sizes and they absorb heat differently from the surroundings, then the frost does the rest to move the stones.S Solbacken (Lindome) said:
A more essential question is, why do you want to do this? If the barn has stood since the 1800s, isn't that proof that the construction works excellently as it is? Experience also tells us that making a cold-stone foundation wall sealed with concrete creates more problems than it solves. What is the frame? Timbered, post-and-beam, half-timbered?
The sill doesn't rest on the entire foundation - just the corners and a few larger stones along the way. The rest is just stacked underneath to dampen the wind and attempt to make it a bit tighter/warmer. Perhaps they have also shoveled up earth inside for the same purpose.
Have any of the corners started to settle, or has a corner stone shifted? Is the sill sagging anywhere? Is the sill made of sound timber?
Frost heave can sometimes cause bearing stones like corner stones to shift, making the sill skew. The solution is not to try to "reinforce" the stones with concrete. The solution is to
The sill doesn't rest on the entire foundation - just the corners and a few larger stones along the way. The rest is just stacked underneath to dampen the wind and attempt to make it a bit tighter/warmer. Perhaps they have also shoveled up earth inside for the same purpose.
Have any of the corners started to settle, or has a corner stone shifted? Is the sill sagging anywhere? Is the sill made of sound timber?
Frost heave can sometimes cause bearing stones like corner stones to shift, making the sill skew. The solution is not to try to "reinforce" the stones with concrete. The solution is to
- Lift the affected part of the house with jacks until the stones are free, prop up.
- Move the stones aside.
- Dig down a bit where the stones were + a bit larger, fill with crushed stone to ground level.
- Put the stones back, ensuring it is the same height remaining up to the lifted house as it was before.
- Lower the house again.
Thank you for the feedback!
One reason is that I would like to lay an insulated concrete foundation (or equivalent) in part of the barn. The barn has a roughly one-meter-high brick foundation on its other short end, 18 meters away, with a concrete slab where there used to be stalls.
It seems natural, then, to first stabilize the foundation wall?
The other reason is that the asbestos roof covering needs to be replaced, insulation and interior walls need to be added in parts of the barn, and a full additional floor needs to be built for the entire barn. So I'm thinking that what I replace it with will be heavier - which means that the foundation wall might not be dimensioned for the pressure.
But the real problem is that the barn essentially rests on the ground at one of its short ends, and I believe these foundation stones need to be replaced. However, it is so airy that it has stayed dry and fine.
One reason is that I would like to lay an insulated concrete foundation (or equivalent) in part of the barn. The barn has a roughly one-meter-high brick foundation on its other short end, 18 meters away, with a concrete slab where there used to be stalls.
It seems natural, then, to first stabilize the foundation wall?
The other reason is that the asbestos roof covering needs to be replaced, insulation and interior walls need to be added in parts of the barn, and a full additional floor needs to be built for the entire barn. So I'm thinking that what I replace it with will be heavier - which means that the foundation wall might not be dimensioned for the pressure.
But the real problem is that the barn essentially rests on the ground at one of its short ends, and I believe these foundation stones need to be replaced. However, it is so airy that it has stayed dry and fine.
Hm.
I am still skeptical. More weight should not be a problem unless you are talking about furnishing a floor inside the barn as it is built today and not adding an entire new floor on top of the existing one (which is really not recommended). These old buildings are generally HEAVILY over-engineered. By the way, you still haven't answered, what kind of framework is it? Timmerstomme? Resvirke? Skiftesverk? Plankstomme? Can you upload a picture? It does make some difference in advice regarding interior walls and such.
"But what is a real problem is that the barn essentially rests on the ground on one short end, and I think these foundation stones need to be replaced. However, it's so airy that it has remained dry and nice." Again, why solve problems you don't have? If it is airy and nice and the wood is healthy, you have a greater risk of ruining something if you change the construction. Maybe, possibly, it might be wise to dig away topsoil around and replace with gravel, but that may not be necessary either.
The dilemma is that these old frameworks are not compatible with our modern comfort requirements. It is originally a utility building, built for animals, and the comfort reflects that.
The problem in your case is the following:
1. You want it to be warm and comfortable and furnished as a residence (as I understand it?)
2. It has a dry-stone foundation with a crawl space around, so the wind blows right under the floors, making it extremely cold.
3. You want to fill in with concrete to seal the wall and lay insulation and fill in with concrete in the crawl space. This is to avoid cold from the ground and drafts from outside.
The issue is that number 3 on that list brings a lot of risks and a lot of work. It might even be easier, cheaper, and result in better comfort to build an Attefall house or similar elsewhere and leave the barn as it is.
What makes the concrete solution tricky? For several reasons:
A. Aesthetic: the concrete ruins the genuine appearance of the foundation.
B. There should not be concrete directly against wood, otherwise it's just a matter of time before the concrete has absorbed so much moisture into the sill that it begins to rot away, and you have to choose between an extremely laborious and expensive sill replacement or demolishing the barn. Therefore, you must have sill paper or similar between them.
C. The sill is not entirely straight and even like in a modern frame construction. It bends, bulges, and is twisted. Getting it completely sealed with concrete against it, while ensuring there is no concrete directly against the wood, is really difficult, and you will likely end up with several places where it drafts between the sill and the concrete = your insulated foundation no longer serves any purpose, and the floors remain cold indoors.
D. You invite all sorts of problems with moisture in the foundation construction after you fill in with concrete. On the other hand, this can happen even if you don’t fill in with concrete. If you start building insulated floors inside, moisture (vapor) will continue to rise from the ground, but there won't be enough heat from inside (due to the insulation) to dry out the lowest parts of the construction, i.e., the blind floor and joists may begin to rot and/or mold. Pile foundations, for example, have proven to be a risky construction for this very reason.
E. An insanely high number of work hours. For the concrete solution to be sound and long-term, proper drainage is needed around the entire barn, and then insulation on the outside. If it is a dry-stone crawl space, all this is EVEN MORE work, as you would either have to demolish the entire foundation and cast a new one from scratch, or demolish the entire foundation, drain, insulate, and then stack it up again.
Regardless, "embedding the existing foundation wall in concrete" is not a feasible solution. If anything, it's better to demolish the foundation wall entirely and build a well-drained, insulated crawl space around everything. This is an enormous project.
I recommend you read this page and everything else on LFS Web: https://www.lfs-web.se/krypgrund-platta.htm and have another think.
I am still skeptical. More weight should not be a problem unless you are talking about furnishing a floor inside the barn as it is built today and not adding an entire new floor on top of the existing one (which is really not recommended). These old buildings are generally HEAVILY over-engineered. By the way, you still haven't answered, what kind of framework is it? Timmerstomme? Resvirke? Skiftesverk? Plankstomme? Can you upload a picture? It does make some difference in advice regarding interior walls and such.
"But what is a real problem is that the barn essentially rests on the ground on one short end, and I think these foundation stones need to be replaced. However, it's so airy that it has remained dry and nice." Again, why solve problems you don't have? If it is airy and nice and the wood is healthy, you have a greater risk of ruining something if you change the construction. Maybe, possibly, it might be wise to dig away topsoil around and replace with gravel, but that may not be necessary either.
The dilemma is that these old frameworks are not compatible with our modern comfort requirements. It is originally a utility building, built for animals, and the comfort reflects that.
The problem in your case is the following:
1. You want it to be warm and comfortable and furnished as a residence (as I understand it?)
2. It has a dry-stone foundation with a crawl space around, so the wind blows right under the floors, making it extremely cold.
3. You want to fill in with concrete to seal the wall and lay insulation and fill in with concrete in the crawl space. This is to avoid cold from the ground and drafts from outside.
The issue is that number 3 on that list brings a lot of risks and a lot of work. It might even be easier, cheaper, and result in better comfort to build an Attefall house or similar elsewhere and leave the barn as it is.
What makes the concrete solution tricky? For several reasons:
A. Aesthetic: the concrete ruins the genuine appearance of the foundation.
B. There should not be concrete directly against wood, otherwise it's just a matter of time before the concrete has absorbed so much moisture into the sill that it begins to rot away, and you have to choose between an extremely laborious and expensive sill replacement or demolishing the barn. Therefore, you must have sill paper or similar between them.
C. The sill is not entirely straight and even like in a modern frame construction. It bends, bulges, and is twisted. Getting it completely sealed with concrete against it, while ensuring there is no concrete directly against the wood, is really difficult, and you will likely end up with several places where it drafts between the sill and the concrete = your insulated foundation no longer serves any purpose, and the floors remain cold indoors.
D. You invite all sorts of problems with moisture in the foundation construction after you fill in with concrete. On the other hand, this can happen even if you don’t fill in with concrete. If you start building insulated floors inside, moisture (vapor) will continue to rise from the ground, but there won't be enough heat from inside (due to the insulation) to dry out the lowest parts of the construction, i.e., the blind floor and joists may begin to rot and/or mold. Pile foundations, for example, have proven to be a risky construction for this very reason.
E. An insanely high number of work hours. For the concrete solution to be sound and long-term, proper drainage is needed around the entire barn, and then insulation on the outside. If it is a dry-stone crawl space, all this is EVEN MORE work, as you would either have to demolish the entire foundation and cast a new one from scratch, or demolish the entire foundation, drain, insulate, and then stack it up again.
Regardless, "embedding the existing foundation wall in concrete" is not a feasible solution. If anything, it's better to demolish the foundation wall entirely and build a well-drained, insulated crawl space around everything. This is an enormous project.
I recommend you read this page and everything else on LFS Web: https://www.lfs-web.se/krypgrund-platta.htm and have another think.