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A strong base is important when building a garden building.

  • RapidGrid Foundations
  • Concrete Bases

Dunster House recommend a flat, level concrete base. If you are unsure about building your concrete base we recommend that you consult an experienced tradesman. Please note that the base needs to be level with no run-off since the building will provide this.

If you prefer not to construct a concrete base, we have designed an excellent foundation system that works well with our garden buildings: the Premium RapidGrid.

RapidGrid Foundations

The Rapid Foundation System is a cost-effective and environmentally friendly alternative to concrete foundations. Generally costing much less than a concrete base, the Rapid Foundations do not ruin the surrounding soil and need very little soil removing compared to if you were laying a concrete base.

rapid grid base foundation for garden buildings

The Premium RapidGrid Foundation System is made up of weed control membrane and high quality, heavy-duty plastic grids. These grids interlock into one another for ease of placement and to help with the rigidity. They create a strong support that will help spread the weight of the building.
With this system, it is better to have reasonably level ground to start off with as you will then need to move less soil in order to level the ground under the grids. Please note that you will need to fill the grids with pea shingle stones, or similar, that you will need to buy from your local builders merchant.

rapid grid base foundation system

The RapidGrid System is also time-efficient. You can get your base into place relatively quickly and with little fuss compared to a concrete base. Simply digging down 30-40mm in medium-firm ground conditions is perfectly sufficient to hold the building stable. There’s no waiting for the base to set and dry, once they’re in you’re ready to start building.

The RapidGrid Foundations are designed to work in medium-firm ground conditions and are suitable for the majority of gardens. Please be aware that they are not suitable for areas prone to waterlogged conditions, marsh, peat or recently disturbed ground. If you are unsure if your ground is suitable for foundations which will exert approx. 17Kpa of pressure, please talk to a local geotechnical engineer prior to purchasing.

(You can level the ground under the grids by moving earth.)

If your ground conditions are not suitable for the Premium RapidGrid foundation due to steep slopes or unstable ground then you may find concrete a better option. This is because all garden buildings need constructing on a flat, level surface.

See how simple it is to install RapidGrids

Concrete Bases

When laying a concrete foundation for your garden building we suggest you add 100mm all the way around the sizes given for the building you have purchased. This will help spread the weight of the building and help ensure that if the base is slightly out of square that the building will still fit on the base. For example:

  • A 4m x 3m building would need a base of approximately 4.2m x 3.2m
  • Any extensions such as SideStores must be taken into account, so a log cabin with a shed measuring a total of 5.5m x 3.0m would need a base of 5.7m x 3.2m

rhine base floor bearer layout



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