ᐅ Sealing the Foundation of a Garden Shed

Hello, I want to set up a wooden garden shed (3x3 m (10x10 ft), 44 mm (1.7 inches) thick, double-glazed) for some fitness equipment and plan to use an old terrace edged with curb stones and paved with concrete slabs (40x40x4 cm (16x16x1.6 inches)).

To protect the shed from rising moisture (e.g., through the joints), I am considering applying a bitumen waterproof membrane over the entire surface.

What do you think about this, or how would you waterproof the base?

Cheers,
jochen35

I would either do the job properly, meaning the substructure plus the floor. Or don’t seal anything at all. Where would any significant moisture come from through the joints?

The substructure and flooring are naturally included with the garden house. My main concern is to protect the wood, especially the substructure that rests directly on the base, from rising moisture.

The substructure is usually made of KDI wood, which is quite durable. Additionally, my garden house company recommended placing pieces of roofing felt about 5mm (0.2 inches) thick between the substructure and the foundation. This prevents standing water at the edge. Nothing is placed under the garden house anyway.

Are you proficient in English? If so, there is a YouTube channel from the English company Oakwood Garden Rooms that showcases really great projects in the UK and demonstrates step-by-step how they build the foundations, waterproofing, roof structures, vapor barriers and retarders, install folding glass walls, and more. Really cool!

WilderSueden schrieb:

The substructure is usually made of KDI-treated wood, which is quite durable. Additionally, my garden shed company recommended placing pieces of roofing felt about 5mm (0.2 inches) thick between the substructure and the foundation. This prevents standing water at the edge. Nothing is placed underneath the garden shed anyway.

How have you secured your garden shed against strong winds? We also have a slab foundation, and since the edging stones are only 6cm (2.4 inches) wide, I don’t want to drill into them from above. Therefore, I plan to fasten the substructure to the edging stones using flat steel straps.