Foundation and edging: The technical foundation for your garden shed

The correct construction of the foundation is the most important prerequisite for the assembly and long-term functionality of your garden shed. As the entire structure is designed to rest on a firm and level surface, the ground must be perfectly level and load-bearing. This is the only way to ensure that the sliding panels remain smooth-running in the long term and that the frame remains free of stress.

There are three tried-and-tested options available for the foundations: a continuous concrete base slab, a professionally laid paving surface, or compacted cobblestones. Particularly for new installations, fitting the paving into a border made of concrete kerbstones has proven effective – the wall structure is later positioned and anchored on these stones.

The ‘80 rule’ and the ‘phase trap’: why millimetres matter

For a wall thickness of 6 cm, we recommend using 8 cm wide kerbstones, known as “80 mm kerbstones”. The extra 2 cm ensure a solid bearing surface and allow for trouble-free anchoring without the stone breaking during drilling – a real risk with narrower stones that can jeopardise the entire stability of the structure. What is often underestimated here is: Almost all standard concrete blocks have a 45-degree chamfer (the so-called ‘bevel’) on their upper edges, approximately 0.5 cm wide. This bevel noticeably reduces the effective usable horizontal bearing surface – with an 80-series kerbstone, only around 7 cm of flat bearing surface often remains after deducting both bevels. Therefore, never plan the foundation dimensions to be flush with the external dimensions of the house; instead, make them approximately 1 cm larger all round. This ensures that the support feet and frame profiles rest fully on the block and do not sit in the area of the bevelled chamfer, which could lead to tilting and instability.

Plan the slope correctly: level beneath the shed, with drainage only behind it

If the foundation or patio is larger than the garden shed’s footprint, special attention must also be paid to water drainage. The direct standing surface beneath the shed must be absolutely level – a slope for rainwater drainage must only begin outside the outer edges of the garden shed. This prevents surface water from running under the floor profiles and ensures controlled drainage away from the building.