No floor slab possible. Poor ground condition / basement?

Hi forum,

we are currently in the detailed planning of our house. For financial reasons, we want to build without a basement; the concept fits that. Today we heard from our future neighbors (plot opposite) that the soil survey showed that a slab foundation is not possible because the soil is too poor and a basement is absolutely necessary. I have never heard of such a thing. Can that be true? Or is someone trying to sell a basement?

Best regards,
Martin

Hello Martin,

Now we heard from our future neighbors (plot opposite) today that the soil survey showed that a slab foundation is not possible because the soil is too poor and a basement is absolutely necessary. I've never heard of anything like that. Could that be true? Or does someone want to sell a basement?

If I'm not mistaken, the basement floor is not founded in mid-air either.

It is more likely that the neighbors would have had to carry out an expensive soil replacement. The costs for a basement then quickly become relative if perhaps only around €10,000 to €15,000 lie between them.

Rhenish regards

Hello construction expert,

all right, that's what I thought too. Do you have any experience with what something like that might cost in the worst case? For a foundation slab for a KFW55 house of about 9x12m? Just roughly... Although the soil would also have to be replaced for a basement, right? I mean, if it's only about 10-15K€ difference and I could maybe make the house a bit smaller because I can move the utility room and the office to the basement, then that's actually something to consider. Well, let's see!

Thank you very much!

We need to have so-called Schroppen incorporated into the ground to reinforce the soil. Up to about 1.5 m depth, the soil is quite "wobbly," below that it looks much better.

We have the offer to get this soil reinforcement for just under €10,000 (including soil excavation and removal). A basement would have cost around €30,000 as a WU basement WITHOUT earthworks (rough estimate: €15,000). That made the decision easy.

We are building a floor slab measuring 9x11 m.

A soil survey is still worthwhile, as the soil expert will also tell you what measures you should take. Then you can get concrete offers from the craftsmen.