Saving by cantilevering the ground floor over the basement?

Hello everyone,

we are currently struggling a bit to align an architect's draft with our budget. Where there is still plenty of space technically at the moment is the basement (completely doing without it is not practical). A partial basement, where the building above then also rests outside the basement, is likely to be complex. Hardly any savings.

But are there maybe experience values/rough estimates regarding the cantilevering of the basement ceiling beyond the basement? For example, 1 to 1.5 m? This way, some basement space could be given up and ideally there would only be some additional effort with the reinforcement of the basement ceiling. At least that is my amateurish idea.

However, it does not seem to be implemented very often. So a considerable additional effort that outweighs the savings on the basement?

Many thanks for all comments and ideas!

We have that - but only because we have a bay window that simply does not extend into the basement. It should actually have been done back then. I doubt that one can clearly say afterwards "You have now saved 4000 euros".

Hello,

A partial basement, where the building above then also rests outside the basement, is likely to be complex. Hardly any savings.

Correct.

But are there perhaps empirical values/rule-of-thumb estimates regarding the cantilevering of the basement ceiling beyond the basement? For example, 1 to 1.5 m? This way, you could give up some basement space and in the best case only have a bit more effort with reinforcing the basement ceiling. At least that’s my layman’s idea.

However, it doesn’t seem to be implemented that often. So it really is a significant additional effort that outweighs the savings on the basement?

Because - strictly speaking - it is equivalent to a partial basement. You would have to support the overhang again; therefore, you can just extend the basement to the rear edge of the floor slab.

Rhenish regards

Exactly, with me the wall supports were set into the ground beyond the frost skirt - I believe I did not save anything there.

Rather, the area must additionally be sealed with bitumen sheets and the ground floor must also be underlaid with perimeter insulation. I do everything myself, so the effort/costs are rather low, but if you contract it out, you might even pay extra for it later.

We have that - but only because we have a bay window that just doesn’t extend into the basement.

Why didn’t you "take along" the basement?

Rhenish regards

Good question - as of now I probably would have done it. Back then, one didn’t have an eye for it...

And the room would just jump outward by 3 meters in the middle because of that - somehow that would also be strange there.

But you’re right, in principle I should have done it.