ᐅ Screw foundations as an affordable alternative to concrete slabs?

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

Hello, this is how I would build my next house 😉 On my brother’s property, there is a tiny house founded exactly like this. The main reasons are cost optimization and, clearly, an ecological approach. Concrete (cement) is responsible for the largest share of CO2 emissions worldwide...

Unfortunately, I have no personal experience beyond the external view of the mentioned foundation. I believe I heard that this construction method is more common in the Netherlands.

I still have some concerns about whether any pests might settle under the house since it is built on stilts. Our architect says it is so drafty down there that nothing would want to get in. Another concern is the durability of the galvanized screw piles in the ground.

Schwabe23 schrieb:

I still have some concerns about whether any pests might nest under the house since it is built on stilts. Our architect says it’s so drafty down there that nothing would want to enter. Another concern is the durability of the galvanized screw anchors in the soil.

These concerns are unfounded. Houses built on stilts are state-of-the-art construction. A so-called "crawl space" that is fully enclosed can address these concerns.

Galvanized screw anchors are nothing new either. Unfortunately, this specific technique has not become widespread in Germany due to lack of lobbying.

In the end, I decided against this method for my carport because the costs would have been too high in my case.

For a larger number of anchors, this is certainly an efficient solution.

Try searching for screw ground anchors. You will find quite a bit of information.

The process is proven, and we would have chosen it as well if our plot had allowed for it. It’s great that your architect is thoughtful and doesn’t just offer a run-of-the-mill standard solution.

Hello,

Schwabe23 schrieb:

Our architect says it’s so drafty down there that nothing wants to go in.

I would take that statement with a lot of caution, at least. I once had the experience of having my office in such a construction. You could definitely hear things moving around under your feet. But it got even worse... At some point, there was an outbreak of myxomatosis (rabbit disease) in the area, and the animals hid under the bungalow to die. We had the smell of decomposition in the offices for weeks! Not pleasant!

Technically, it might be a good solution—most houses in northern latitudes (permafrost ground) are built this way. But it must be absolutely certain that nothing can crawl underneath!

Best regards,

Andreas