Unfortunately, the only way around that is to raise the walls a few mm to get plastic in between, possibly if it is *only* stone, to attach the plastic with butyl sealant or something else effective and environmentally unfriendly against the stone. ;-) Lifting a small section at a time shouldn't be a problem, although somewhat time-consuming.
The problem with Leca is that it wears and gets damaged during transport and compression, so in lab tests, it's good, but in practice, there are damaged pellets and dust mixed in, similar to unwashed macadam. Unfortunately, very good material otherwise, but in all uses, this problem doesn't matter.
Another disadvantage in your case is that the low mass can cause the foundation to move inward as it presumably rests on the ground and the loose structure has absorbed frost movements.
As always with old houses, they have their quirks depending on location and details, so what is simple and good in one is terrible in another. (By the way, this applies to new ones too
)
By the way, is the house intended for year-round living?
The problem with Leca is that it wears and gets damaged during transport and compression, so in lab tests, it's good, but in practice, there are damaged pellets and dust mixed in, similar to unwashed macadam. Unfortunately, very good material otherwise, but in all uses, this problem doesn't matter.
Another disadvantage in your case is that the low mass can cause the foundation to move inward as it presumably rests on the ground and the loose structure has absorbed frost movements.
As always with old houses, they have their quirks depending on location and details, so what is simple and good in one is terrible in another. (By the way, this applies to new ones too
)By the way, is the house intended for year-round living?
Very good thoughts there, thank you. And the house will mainly be a summer residence, but there will also be a weekend now and then during the other seasons. At present, it is completely insanely poor in terms of heating, it takes about 6-7 kW to maintain 20 degrees inside if it's -10 degrees outside. On 40 m2...
You didn't say anything about the condition of what you dug up? Does it seem like there has been moisture migration in via the mullbänk? If it has held up before, maybe the simplest solution is to refill the foundation but ensure it drains better (that sounded theoretical as heck)...
I haven't found anything more sensible (from a building conservation perspective) other than these that use clay to fill the trossbotten. Draught-free if you fill tightly against the sill (preferably so it blends with a clay plaster)...
In an excavated foundation, it was also recommended to ensure there is a tight seal between the bottom sill and the stone foundation. I assume you want the moisture migration to occur somewhere other than towards/by the bottom sill. Ventilation, according to the article, takes place a bit below but still through the foundation.
I actually think that if you can get the height of the lecakulorna right, it should be a good solution. Just remember to build in pipes, etc., so they can be insulated separately, especially if you're going to have some heating to prevent freezing of, for example, water...
The exterior part (drainage/ground insulation) is also an option even if it's for leisure use since they are relatively inexpensive measures. Ground insulation also counteracts ground movements because it gets warmer under the house...
I haven't found anything more sensible (from a building conservation perspective) other than these that use clay to fill the trossbotten. Draught-free if you fill tightly against the sill (preferably so it blends with a clay plaster)...
In an excavated foundation, it was also recommended to ensure there is a tight seal between the bottom sill and the stone foundation. I assume you want the moisture migration to occur somewhere other than towards/by the bottom sill. Ventilation, according to the article, takes place a bit below but still through the foundation.
I actually think that if you can get the height of the lecakulorna right, it should be a good solution. Just remember to build in pipes, etc., so they can be insulated separately, especially if you're going to have some heating to prevent freezing of, for example, water...
The exterior part (drainage/ground insulation) is also an option even if it's for leisure use since they are relatively inexpensive measures. Ground insulation also counteracts ground movements because it gets warmer under the house...
I haven't actually torn up the floor yet, but it will probably be in pretty bad shape. There is both an old linoleum mat, joists and chipboard, and a plastic mat on the floor, so the moisture level might have gotten quite high, regardless of whether it has worked for 150 years before the mats were laid. I'll come back with some pictures when I've torn it up in a month or so.
Has anyone tried installing foam boards on the outermost part? There might be a risk of moisture issues that can't migrate upwards right there, but the rest of the floor should suffice?
What have you used/are you planning to use for insulation in the floors? I'm skeptical about anything other than cellulose since I've heard horror stories about old houses with moldy glass wool...
jon_h: how has the digging gone and have you come up with a working solution?
What have you used/are you planning to use for insulation in the floors? I'm skeptical about anything other than cellulose since I've heard horror stories about old houses with moldy glass wool...
jon_h: how has the digging gone and have you come up with a working solution?
But that doesn't really solve my problem. The insulation I use doesn't really matter if it has to be placed in a beam structure with a subfloor. It's just that such a thing can't be installed in a satisfactory way. But thank you for your input anyway.
Ok, you can report when you've made progress! I only have a few wheelbarrows of soil/sand left. I'm currently down to about 70-80cm deep. Then a few små kattgluggar need to be made, drainage around a corner done. Some stones in the foundation will get some support concrete to keep them in place. Then it's time for the floor joists and insulation!
For me, it's close now! All the soil is out, cat flaps in place. A few loads of gravel are needed, then it's time for the floor beams. The plan now is to cast posts as far out towards the outer walls as possible and anchor the beams in them. But I haven't solved the problem yet with insulation and the bottom against the outer wall.
I tore up the floor last week and found a strange construction, not at all what I expected after tearing up the floor in the chamber. They had placed 20 cm high beams directly on the ground, and about halfway up these, they constructed a subfloor which they then filled with pure charcoal. However, this construction stopped half a meter inside all exterior walls, where they instead filled it with stones (about 20-50 mm in size) and then lime mortar. I have never seen or heard of anything like it. Most of the subfloor had collapsed, and the beams were slightly affected by rot at the bottom, but overall, it was in incredibly much better condition than I expected.
The demolition continues next week, or the week after, and I will be back with pictures when I have the camera handy.
The demolition continues next week, or the week after, and I will be back with pictures when I have the camera handy.
I have only skimmed through the thread, but my initial reaction is - do not build a crawl space (externally ventilated foundation) where there isn't one already! The externally ventilated foundation is inherently a risky structure, especially in summer when humid air "blows in" and condenses in the cooler space. It's not always necessary to ventilate the foundation!
Consult knowledgeable people in building preservation, there are other ways to handle it! As you noticed yourself, the beams weren't in as bad a condition as you thought. There are many examples where beams placed directly on the ground or in sand have fared excellently! I don't have a direct solution but there's plenty of literature, knowledgeable people to ask, and journals, e.g., "Byggnadskultur".
As I said, I read the thread quickly, so with the reservation that I may have misunderstood something
Consult knowledgeable people in building preservation, there are other ways to handle it! As you noticed yourself, the beams weren't in as bad a condition as you thought. There are many examples where beams placed directly on the ground or in sand have fared excellently! I don't have a direct solution but there's plenty of literature, knowledgeable people to ask, and journals, e.g., "Byggnadskultur".
As I said, I read the thread quickly, so with the reservation that I may have misunderstood something
I have a similar floor construction that I am renovating. After some discussions with a serious carpenter, we concluded that the safest in my case is to recreate the same construction, but with fresh materials. It will be like a traditional joist floor with only 70 mm insulation and only about 10 cm of air against the ground in the foundation. The same construction as before, but I will replace 10 cm of wood shavings with 70 mm insulation and swap out the rotten beams for joists. My beams were lying on stones directly on the ground. A lot of old organic material has been there since the 1940s, which I will clean out as well as possible. Otherwise, I hope the renewed warm foundation will last for another 65 years.