Concrete Slab Foundations

Concrete Slab Foundations

Before investing in a garden building, it is important to ensure you have selected the most suitable Garden Room Foundation.

Foundations are crucial to the durability, longevity and stability of a build, and this article will explore the use of a concrete slab as your base type.

Installing Your Concrete Slab

We always recommend your concrete slab to be the same footprint size as the studio going on top. We recommend this because if your concrete slab is larger than your studio footprint, it poses a risk of standing water, which could get under the SIPs panels and overtime cause rotting. In this scenario, you would need to use pea gravel or such like, to eliminate this risk.

We also always recommend your concrete slab to be a minimum of 50mm below and 50mm above ground level. This thickness would then offer enough strength and be sturdy enough to support the garden room going on top of it. Not only this, but by being 50mm above ground level, it prevents any water going under the SIP panels and posing the same risk of rotting, as mentioned above.

Our SIPs Kits

When supplying our bespoke SIPs Kits, we will always confirm what foundation type you will be using prior to engineering and manufacturing your studio. This will then determine how we supply your SIPs floor, as part of the kit.

For a concrete slab base, the SIPs floor panels would be fitted with a membrane and battens, to lift off the concrete slab and allow for airflow. (This is all included in the SIPs Kit price).

SIPS kit ready to use

Pros Of A Concrete Slab Foundation

Excellent Stability

A level concrete slab is the most solid foundation choice. If you plan to use your garden room as a gym, or are looking to have heavy equipment in there, we recommend using an insulated concrete slab as your base type. We would then supply a walls and roof only SIPs Kit (no floor), to remove the risk of movement and flexing in the SIPs floor.


Traditional concrete slabs are one of the oldest methods of foundations and are still the most popular choice for many, due to their excellent long-term stability.

Prevent the risk of animals nesting or weeds growing

The underside of the SIPs floor is fitted with timber battens, which only leaves a small gap between the studio and concrete slab. This therefore prevents any animals from being able to nest underneath your studio, as well as the concrete slab preventing any weeds from growing.

Cons Of A Concrete Slab Foundation

✗ Labour intensive

It is essential that the concrete slab foundation is square and level, meaning it takes skill to install. This is why some people tend to find easier and less messy foundation types for their garden rooms.

✗ Time consuming

Before installing the concrete slab, it is important to ensure the ground is properly prepared. Not only this, but after the slab has been laid, you will need to allow enough time for the concrete to dry fully, although sometimes this can be weather dependent.

✗ Risk of subsidising

It is important to consider the soil conditions and distance from trees before installing your concrete slab. If the ground were to lose too much moisture and shrink, due to trees, this can lead to subsidence, causing cracks in the concrete slab.

Please contact us if you have any queries regarding base types.

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