ᐅ Frost Skirt – Advantages and Disadvantages

Ippebson schrieb:

Sure?

Good luck

Of course, what else would it be for? Strip footings are used to transfer the load of the walls in single-family homes without a basement, providing a frost-proof foundation. In our case, even with a basement, a strip footing was constructed because the soil consists of clay and sand.

I am copying the description as it appears in my contract. I also have a slab foundation with a frost skirt, for normal soil conditions.

For improved thermal insulation, an approximately 8 cm (3 inches) thick vertical insulation layer is installed continuously between the ground and the foundation concrete to a depth of about 40–60 cm (16–24 inches) as a frost and thermal protection skirt. This construction demonstrates our expertise in energy efficiency starting already at the foundation stage.

I am not a professional civil engineer and am happy to be corrected, but a frost skirt is not the same as a strip foundation. The former is designed to keep water away, while the latter is meant to transfer loads. They may look similar in construction because concrete is poured into a trench, but they serve entirely different purposes.

Of course, you can build on strip foundations (which should be placed below the frost line), but then the slab is dimensioned differently and is no longer (solely) responsible for load bearing, which would otherwise be an unnecessary expense. When the slab itself is used for load transfer, a strip foundation is not needed, but you must find a way to prevent the slab from being lifted by freezing water. This can be achieved with a surrounding waterproof concrete wall – that is, a frost skirt. Alternatively, it can be done by replacing the ground beneath with frost-resistant material, such as cellular glass gravel or similar.

Insulating the (strip) foundation or the edge of the slab is intended to prevent thermal bridges in these areas, but it will certainly not keep frost away. Strictly speaking, insulating these parts can even be counterproductive in this context, as it prevents the ground there from benefiting from the building’s heat.

Frost skirts are usually omitted in construction with a load-bearing slab foundation to ensure continuous thermal insulation around the building. They are functionally unnecessary on soils that are not frost-prone. They can also be cost-effectively installed using gravel where this condition does not naturally exist.

This has nothing to do with being stingy. The necessity is documented through a soil report.

There are many ways to reach the same goal.

This is not entirely accurate. The "template" always requires a frost skirt for concrete slab foundations. It is a relatively recent argument that if the soil beneath the foundation is frost-proof, frost protection is considered sufficient.

Check if you can find a building without a frost skirt for a public client; due to anticipated legal disputes, this is unlikely.

Hello,
as already mentioned, the need for a frost skirt arises from the soil survey.
For our general contractor, a load-bearing soil foundation with a thickness of 25 cm (10 inches) frost-free was standard. Due to the soil conditions (seasonal frost), an additional continuous unreinforced frost skirt had to be installed.