Garage foundation - strip foundation or just a floor slab?

Hello,

when strip foundations are used, in our latitudes, a depth of 80 cm is considered frost-free, meaning that below this depth there will be no frost in the ground. The problem only arises when a frost bubble forms under a building, which expands due to the freezing water and pushes the building upwards. This can be prevented by either 1. placing the building on soil that no longer freezes, i.e., 80 cm deep, or 2. installing a so-called capillary-breaking layer. Usually gravel made of natural stones. Through this capillary-breaking layer, water cannot rise to the building, freeze, and push it upwards.

So: To reliably exclude any upward movement of the building, I would use a strip foundation, which can be excavated with a mini excavator in 2 hours and can be concreted together with the reinforced ground slab. The additional costs for the concrete are therefore very limited if the concrete truck is coming anyway.

I hope I was able to help a bit.

Regards

Hello Blockhauspower,
yes, it's slowly dawning on me. Thank you very much. I will follow your suggestion. Since at least in our area there is always a minimum quantity surcharge for ready-mix concrete and I also have to rent an "expensive" additional pump due to the distance, it makes sense to create the strip foundation and the base slab together. And for this, I have two questions again:

1) Is the base slab poured over the strip foundation (connection slab with strip foundation) or only up to the edge of the strip foundation (slab lies inside)?

2) The approximately 15 cm thick capillary-breaking gravel layer will still be compacted with a vibrating plate, but will the gravel layer (FS gravel, RI0-45mm) hold if there will be about 15 cm of concrete on top, or can the gravel layer break out laterally at the same height into the strip foundations?

Thank you very much in advance
Regards Duke

hello

or only up to the edge of the strip footing (slab lies inside)?

which forces act on the foundation
if the slab is not connected to the foundation
(slab lies inside) styrofoam all around
(subsoil sand)

6x4m 10cm thick

possibly with an expansion joint in the middle and little reinforcement

regards
Window