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2 replies
892 views
2 replies
Concrete shell on the outside of ISO-leca foundation
Hello,
I would like to discuss this with you
Basement foundation under construction, by Finja Exakt 30cm ISO-block, approximately 120m2 slab and 260cm high foundation wall. On Finja's slab exactly.
To avoid rendering for several hundreds of thousands and potential future problems with vapor tightness, cracks, and who knows what, - we are considering instead casting a concrete "shell" around the entire basement floor of the house. The basement foundation is 60% below ground. Panels below ground and raw wood with a wood pattern above ground.
I'm thinking that one could attach a coarse reinforcement mesh with a few centimeters of distance from the unrendered Leca wall. Then we form the outside and cast 10cm of concrete.
What I'm uncertain about:
1. Whether we should have an extra layer of EPS under the foundation slab that extends out 10-15cm which the concrete shell is cast down against, to possibly mitigate capillary action. Or if you simply cast down onto the gravel, or onto a geotextile that lies on the gravel.
2. If during the curing of the concrete, tensions could cause it to detach from the Leca wall and cause the Leca to crack.
3. If it could create tensions during casting that cause the Leca to detach from the insulation core.
4. If there even are form ties long enough to go through 30cm of Leca, form, and counter hold. For a "reasonable" cost.
Then of course I am interested in your opinions. We will also talk to a structural engineer, but I'm afraid this is so unusual that no engineer has gotten these questions before. Therefore it felt good to ask on the forum.
The goal is to achieve a beautiful wood-patterned concrete surface, which is durable, relatively vapor tight, and robust.
I would like to discuss this with you
Basement foundation under construction, by Finja Exakt 30cm ISO-block, approximately 120m2 slab and 260cm high foundation wall. On Finja's slab exactly.
To avoid rendering for several hundreds of thousands and potential future problems with vapor tightness, cracks, and who knows what, - we are considering instead casting a concrete "shell" around the entire basement floor of the house. The basement foundation is 60% below ground. Panels below ground and raw wood with a wood pattern above ground.
I'm thinking that one could attach a coarse reinforcement mesh with a few centimeters of distance from the unrendered Leca wall. Then we form the outside and cast 10cm of concrete.
What I'm uncertain about:
1. Whether we should have an extra layer of EPS under the foundation slab that extends out 10-15cm which the concrete shell is cast down against, to possibly mitigate capillary action. Or if you simply cast down onto the gravel, or onto a geotextile that lies on the gravel.
2. If during the curing of the concrete, tensions could cause it to detach from the Leca wall and cause the Leca to crack.
3. If it could create tensions during casting that cause the Leca to detach from the insulation core.
4. If there even are form ties long enough to go through 30cm of Leca, form, and counter hold. For a "reasonable" cost.
Then of course I am interested in your opinions. We will also talk to a structural engineer, but I'm afraid this is so unusual that no engineer has gotten these questions before. Therefore it felt good to ask on the forum.
The goal is to achieve a beautiful wood-patterned concrete surface, which is durable, relatively vapor tight, and robust.
A anders_oj said:Hello,
I would like to discuss this with you.
Foundation under construction, by Finja Exakt 30cm ISO-block, approximately 120m2 slab and 260cm high foundation wall. On Finja's slab exactly.
To avoid plastering for several hundred thousand and potential future problems with vapor tightness, cracks and god knows what, - we are considering instead casting a "shell" of concrete around the entire basement floor. The basement foundation is 60% below ground. Panels below ground and tongue and groove with wood pattern above ground.
I would NEVER choose to build underground with an ISO-block, IF the wall has a lot of earth pressure against it.
Better then to build with solid Leca blocks with every other layer double rebar 8 mm & have plenty of isodrän-insulation & fabric outside the Leca.
And it doesn't have to cost hundreds of thousands to fix the surface so it becomes pore-free/sealed, you can mix regular mortar cement with water & just plaster the entire surface thoroughly so it becomes sealed. (so maybe a few 1000s)
Your idea sounds like extreme "over course" & expensive, & what would you gain with that work method?
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