Hello everyone,
I am planning a solid foundation for my garden shed, measuring 3 x 4 m (9.8 x 13.1 ft) with 5 cm (2 inches) thick walls. It will be used as a workshop. The roof will consist of sandwich panels and photovoltaic modules, so it will have some weight.
I spoke with neighbors who told me that there is a solid layer of sand starting at about 70 cm (28 inches) below ground here, on which everything is built. Unfortunately, the soil here is partly construction debris and earth, and due to space constraints, I have to dig everything by hand. Therefore, I am considering two strip footings along the 3 m (9.8 ft) sides, with a concrete slab on top about 15–20 cm (6–8 inches) thick. I have already excavated about 30 cm (12 inches), and on one side, I dug the strip footing down to nearly 80 cm (31 inches). Here it became clear that the soil suddenly becomes very solid.
Now my question: Is it sufficient for the slab foundation to be supported only along the 3 m (9.8 ft) sides down to 80 cm (31 inches) reaching the firm sand layer?
Here is a small drawing.
I am planning a solid foundation for my garden shed, measuring 3 x 4 m (9.8 x 13.1 ft) with 5 cm (2 inches) thick walls. It will be used as a workshop. The roof will consist of sandwich panels and photovoltaic modules, so it will have some weight.
I spoke with neighbors who told me that there is a solid layer of sand starting at about 70 cm (28 inches) below ground here, on which everything is built. Unfortunately, the soil here is partly construction debris and earth, and due to space constraints, I have to dig everything by hand. Therefore, I am considering two strip footings along the 3 m (9.8 ft) sides, with a concrete slab on top about 15–20 cm (6–8 inches) thick. I have already excavated about 30 cm (12 inches), and on one side, I dug the strip footing down to nearly 80 cm (31 inches). Here it became clear that the soil suddenly becomes very solid.
Now my question: Is it sufficient for the slab foundation to be supported only along the 3 m (9.8 ft) sides down to 80 cm (31 inches) reaching the firm sand layer?
Here is a small drawing.
M
MachsSelbst5 May 2026 13:30Only that a garden shed should not actually be sold without a foundation plan.