ᐅ Screw foundations as an affordable alternative to concrete slabs?
Created on: 25 Jun 2021 20:19
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Schwabe23
Hello everyone,
Our architect has proposed a screw foundation for our wooden house. The house will be supported on a wooden floor resting on screwed-in sleeves, similar to a pile foundation. The supply lines will be placed inside a small, frost-protected enclosure. This solution was mainly suggested to save costs, but for us, it is also an advantage that the area remains completely removable. We have no special conditions on the plot—gravelly soil with a slight slope and no groundwater. Does anyone have experience with this type of foundation? What are the advantages and disadvantages?
I’m surprised that there is hardly any information available about this. Why isn’t it used more often in timber construction since it is apparently much more cost-effective?
Greetings from the south
Our architect has proposed a screw foundation for our wooden house. The house will be supported on a wooden floor resting on screwed-in sleeves, similar to a pile foundation. The supply lines will be placed inside a small, frost-protected enclosure. This solution was mainly suggested to save costs, but for us, it is also an advantage that the area remains completely removable. We have no special conditions on the plot—gravelly soil with a slight slope and no groundwater. Does anyone have experience with this type of foundation? What are the advantages and disadvantages?
I’m surprised that there is hardly any information available about this. Why isn’t it used more often in timber construction since it is apparently much more cost-effective?
Greetings from the south
DavidTR schrieb:
I’ll give it a try right away in the first post:
We are currently in the early planning stages for a house. One thing is certain: it should be made of wood (exact type still undecided) and built on screw piles. We had actually already selected a company and even visited their factory, but they recently filed for bankruptcy...
So my question goes beyond experiences — I would also like to know if anyone knows companies (other than Staudenschreiner, they are too far away for us) that install these foundations or, even better, act as general contractors to build houses as turnkey as possible. Google has not been very helpful in this regard.
I’m located near Trier, so the carpentry company of @Paswina might even be an option.
Thanks in advance Hi David!
Google wasn’t very helpful for us either, at least not for wooden floor slabs. I ended up contacting many local carpentry companies, and a few had experience with this kind of foundation. But they just hadn’t advertised it on their websites. So it might be worth checking with local carpenters near you — you could find someone who can do it or has already done it before.
Our builder was open to it initially and could have built it with help from Staudenschreiner, but eventually declined because it was probably too expensive...
Do you have any companies for screw pile foundations in your area?
Best regards
Pascal
Hello Pascal,
Ideally, we want everything from one source, or at least the foundation and the shell structure. For this reason, we have not yet looked for companies that only install screw pile foundations. I haven’t pursued the idea of simply contacting carpentry firms either, but I will probably have to do that if I can’t find anyone offering a complete package. In the meantime, I have scheduled a few initial meetings with companies, and despite mentioning the screw pile foundation, none of them have backed out.
Best regards
Ideally, we want everything from one source, or at least the foundation and the shell structure. For this reason, we have not yet looked for companies that only install screw pile foundations. I haven’t pursued the idea of simply contacting carpentry firms either, but I will probably have to do that if I can’t find anyone offering a complete package. In the meantime, I have scheduled a few initial meetings with companies, and despite mentioning the screw pile foundation, none of them have backed out.
Best regards
Hi,
now that you mention it, a carpentry company was also supposed to take care of the screw foundations, but I already have a quote for that, so they don’t need to do it anymore. It shouldn’t be a big deal, the manufacturers are well known and can coordinate themselves. However, finding a carpentry company that also actually installs the screw foundations might take a bit longer! Good luck and feel free to keep me updated.
now that you mention it, a carpentry company was also supposed to take care of the screw foundations, but I already have a quote for that, so they don’t need to do it anymore. It shouldn’t be a big deal, the manufacturers are well known and can coordinate themselves. However, finding a carpentry company that also actually installs the screw foundations might take a bit longer! Good luck and feel free to keep me updated.
DavidTR schrieb:
Hello Pascal,
We would prefer to have everything from a single source, at least the foundation and the shell. For this reason, we haven’t looked for companies that only install screw piles yet. I haven’t pursued the idea of simply contacting carpenters either, for the same reason, but I’ll probably have to if I can’t find anyone offering a complete package. In the meantime, I have arranged a few initial meetings with companies, and despite my mentioning the screw foundation, none of them have backed out.
Best regards Hi David,
a brief update from us: unfortunately, we are no longer pursuing the idea of screw foundations / timber ground slabs. Since we don’t have an architect, I had to manage everything myself, and some important information was either overlooked by me or I didn’t ask enough detailed questions. We have received the structural calculations for the house – the concrete slab installers will calculate their own structural design. This is what the house builder communicated to me as well. Unfortunately, the carpentry companies see it differently, and having the structural calculations redone would eliminate any potential financial advantage of the screw foundations and timber ground slab. We are now back to the standard approach with earthworks and insulated concrete slab. Good luck with your project!
Paswina schrieb:
Hi David,
a quick update from us: unfortunately, we are no longer pursuing the idea of screw foundations / wooden floor slabs. Since we don't have an architect, I had to handle everything myself, and important information was "overlooked" or I didn’t ask in detail. We received the structural engineering for the house – based on this, the concrete slab contractors will calculate their own structural design. This is how the builder communicated it to me. Unfortunately, the carpenters see it differently, and having the structural calculations redone would eliminate the potential financial benefit of the screw foundations and wooden floor slab. We are now back to the standard approach with groundwork and a concrete slab with underfloor insulation. Good luck with your project!Hello Pascal,
As of today, we are sticking with it! The company that will most likely build our house had no concerns about the screw foundations, although they usually don’t install them themselves. The wooden floor slab will be manufactured by them, and they will also do the structural calculations. In the meantime, I have found two companies that will install the screws (of course, only following a soil survey and engineering calculations). Currently, we are awaiting the result of a building inquiry; unfortunately, the responsible authority is not very fast. Since our site has nearly a 20% slope, building with concrete would basically mean constructing a basement. Initial rough cost estimates show a price difference in the range of 80,000 to 130,000 euros in favor of the screw foundations!
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thangorodrim19 Apr 2024 16:12If it only makes an 80 Euro difference, I would stick with a concrete foundation.
Just kidding, this sounds really interesting for timber construction. When I last checked about six months ago, I found some comments along the lines of "you need an exceptional structural analysis" or "this is not so easily done in Germany at all." Was there no problem with this, and did the building authorities and structural engineer simply approve it?
Regarding slab-on-grade/concrete foundation versus screw foundation/wood floor panel, I would now expect less of a cost advantage.
How is it possible for a basement as a hillside house to be built on screw foundations? I would expect that one side would have to be excavated, so you would have to pour concrete anyway, and a hybrid of concrete and screw foundations would negate all the advantages. Where is the cost advantage coming from?
Just kidding, this sounds really interesting for timber construction. When I last checked about six months ago, I found some comments along the lines of "you need an exceptional structural analysis" or "this is not so easily done in Germany at all." Was there no problem with this, and did the building authorities and structural engineer simply approve it?
Regarding slab-on-grade/concrete foundation versus screw foundation/wood floor panel, I would now expect less of a cost advantage.
How is it possible for a basement as a hillside house to be built on screw foundations? I would expect that one side would have to be excavated, so you would have to pour concrete anyway, and a hybrid of concrete and screw foundations would negate all the advantages. Where is the cost advantage coming from?
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