How many ground screws do I need for my project?

Several factors can influence the number of ground screws you may require for a project.

Some primary considerations are listed below, but if you would like assistance planning for your project, contact your local installer, who'll be happy to help.

A garden room sitting on ground screws

What type of structure are you supporting

You will require more ground screws to support a heavy timber frame building, such as a garden office, than a decking area of a similar size. Loads are transferred through the structure to the foundations, with loads being distributed evenly across the number of ground screws installed.

ground screw foundations over sloping ground

What size of subframe you are installing

It is also essential to consider the main support structure installed on your foundations to avoid deflection between fixed points. Ground screws are typically installed in a grid pattern to support the frame sitting on top. For example, an 8″ x 2″ timber will span a greater distance than a 4″ x 2″ timber. Therefore, ground screws may be installed closer together on a lighter frame to avoid excessive deflection between fixed points.

ground screw foundations installed in soft ground

What the ground conditions and soil types are

These can vary significantly and may determine how many ground screws are required. If ground conditions are determined to be less favourable, offering less than the average load-bearing capacities, you may need a greater number of ground screws to spread the load. Alternatively, we may install longer ground screws to reach better, load-bearing ground.

garden room and hot tub on ground screw foundations

Contents and additional heavy loads

You may be getting a hot tub installed or using your space as a home gym. If you have specific areas where loads may be greater than others, we would advise additional ground screws at those locations. Additional ground screws will allow for the extra weight to be transferred through your foundations and adequately support your sub-frame to avoid deflection.

To give an insight into the number of screws you might need, below is an example project for a 4m x 3m garden room with an extended decking area.

example foundations layout for a garden room project

Our team is always on hand to advise and assist with your project. 

If you require help, please contact your local installer, who'll be happy to help.

Are you planning a project?

Our teams will be happy to answer any questions you have about ground screws and share how they can help get your project underway with minimal mess, hassle or environmental impact.

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Do you have a question?

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