Ground screws or concrete base? A beginners guide.

Ground screws or concrete base? A beginners guide.

We are familiar with the sight of deep concrete foundations being laid as new buildings are constructed. They give a similar feeling to the noise and scale of an aircraft engine in that we don’t need to understand the technicalities to happily put trust in the solid and robust mechanics.

Ground screws offer an alternative to concrete foundations that meets many contemporary demands and expectations.

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Ground screws have been in use since the 1830’s when engineers battled with unstable soils and bases to create secure foundations. Early examples were typically timber posts driven into the soil but, as product technology progressed, they have become recognised as robust, adaptable, and eco-friendly alternatives to traditional methods.

A garden office could take advantage of a ground screws or a concrete base. Here are the seven topics we will consider when recommending, the best option for your project.

Size and scale

Concrete bases would be used where a higher load-bearing capacity is needed for larger structures. This is unlikely to be an issue for most garden offices but is not the only consideration.

Time scales

Ground screws are quicker and less disruptive to install than concrete bases. They need some technical knowledge but there is no excavation or heavy machinery and, unlike concrete (which needs to set), we can move quickly to the next phases of the project. Ground screws are also less dependent on good weather!

Flexibility

Ground screws are designed to be more adaptable in unstable or unpredictable environments (think sloping or uneven garden space). This could be important if you want to make use of otherwise redundant spaces where options for alternative uses are limited.

Environment

The production of ground screws has a far lower environmental impact and they are easy to remove (and potentially re-use) when plans change in the future. Their use also creates far less noise which will benefit you and your neighbours!

Costs

There is a higher ‘product’ cost for ground screws but the reduced installation time, minimal/no excavation, and easy disposal of materials associated with their use will lead to a lower project and lifetime cost.

Aesthetics

Although ground screws may be the best technical option for sloped landscapes, the visible gap between the floor structure and the ground may be less aesthetically pleasing than a flush concrete base. The screws can be hidden but this should be part of the upfront design (and cost) plan as it may require additional work and materials.

Planning

Ground screws are designed to raise the base of the structure to minimise the impact of the ground conditions. This may give rise to additional planning considerations if it pushes the overall height of the structure beyond ‘permitted development’ limits.

Margin notes...

Personal priorities and the reality of the planned location for the workspace will lead to a design and build decision. It will not be one of the more exciting decisions and you will not see the outcome in the final build. However, it is worth considering that cement, the agent that binds sand with aggregate to make concrete, is a major contributor to climate change. This article from the BBC says the chemistry necessary to produce cement is responsible for 7.5% of annual human made CO2 emissions.

Mybridity will begin the project with a site visit and a discussion of technical and aesthetic options so we can agree outcomes that are aligned to your own priorities.

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