Construction of a base slab with frost skirt but without foundation

Hello everyone,

I would like to ask the experts a question. Currently, I have not yet arrived at the optimal solution:

In 2013 we are building a single-family house with a footprint of 17 x 9 meters.
The whole thing sits on a slab foundation with a thickness of 25 cm, possibly increased to 30 cm (no basement!)
I want a 60mm thick Styrodur insulation under the slab.
My builder initially gave me an offer with strip footings 40 cm wide and insulation on the inside.
However, I want to embed the entire slab in this Styrodur insulation (so to speak, an insulation shell without thermal bridges). A footing would create a thermal bridge again where the slab contacts the footing surface. The builder does not want to formwork the footing. Insulation on the footing side is therefore not possible.
Now I thought we would only make a frost skirt 20 cm wide and 80 cm deep. However, the slab should not rest on this skirt. The frost skirt would run outside the slab.
I hope some experts know what I mean and will share their opinions on this.

Many thanks for your help.

The frost skirt would run outside the base slab.

What else? Have you already discussed this issue with your structural engineer – after all, they also have a say; before making a decision, a soil survey is also necessary. If, for example, you want to apply an ETICS, gravel would probably be the better choice, because you can integrate it (also 80 cm) into the thermal insulation. Kind regards

I don’t have a structural engineer, being stingy is cool. The BUs in Bayern usually do it more by eye. But you convinced me. I’ll have a soil survey done. I believe the bending moments of the slab are not to be neglected without a strip foundation. I want a 36.5 cm wall with T10 bricks and two full stories. The price-performance ratio of the bricks is unbeatable. I’ll plaster the exterior facade first in 2014 and then maybe with full thermal insulation using wood fiber boards (If there’s still money left). Then the heating costs are negligible! I am grateful for further opinions. Regards Singerl

That's nonsense, Singerl

There is no house construction without structural analysis. It is required for the building permit. Your BU will therefore either have its own structural engineer or hire an external one.

Hello,

I don’t have a structural engineer, being stingy is cool. The building authorities in Bavaria also do it more by eye.

Apart from the fact that you are not allowed to build without a structural engineer, you should not be surprised if, in the end, the saying proves true: "pretty cheap turns out pretty expensive!"

Kind regards

What else?

I always thought the frost skirts are flush with the edge of the slab???

Regards