Start with the question your foundation needs to answer
A ground screw product specification and an on-site test provide different information. The product has its own characteristics, but its response once installed also depends on the ground, depth, installation and the force being applied.
Perhaps your engineer needs downward load data for a building. Perhaps wind uplift is an important part of the design. Or you may need evidence before deciding whether a proposed screw is suitable. The reason for the test determines the method, the locations and the information to record.
You can start by explaining the project in ordinary terms. We agree the technical testing requirement with the project team before attendance, including any load calculations and reporting.
Our two main ground screw testing services
Pull testing and compression testing apply forces in opposite directions. Each has a different purpose. The pages below explain the methods and help you discuss the right service.
Upward force · tension · uplift
Ground screw pull testing
An upward load is applied and the screw’s response is recorded. This provides site-specific information about resistance to pull-out or uplift for the agreed test.
Relevant discussions can include exposed structures, solar mounting foundations and other projects where the design includes upward forces.
Downward force · compression
Ground screw load testing
A physical compression test applies a downward load and records the resulting movement. It helps assess the response of the tested screw under the agreed loading.
We also supply compression capacity calculations from pull results where the method is applicable and agreed. The report distinguishes these calculated values from direct compression test results.
Specialist testing by arrangement
Some projects need information beyond upward and downward loading. The following services are available by arrangement for specialist projects. They form part of an agreed brief rather than a standard addition to every visit.
Lateral testing
A sideways load assesses horizontal response where this is part of the foundation requirement. It is distinct from upward or downward axial testing.
Torsional testing
Testing under a twisting action addresses a rotational requirement. A sideways pull is not described as torsion; the test arrangement must match the project question.
Recorded installation torque
Turning resistance is recorded during installation for the agreed project. These records are considered alongside the applicable design and test evidence.
Torque is a different measurement from load. A record of installation resistance does not directly show every force an installed ground screw can resist. Any relationship between torque and load must be justified for the actual foundation and ground; it is not a universal conversion.
From the first enquiry to a written test report
1. Discuss the project
Share the location, structure and any request from your engineer or project team. Existing screw information is useful where testing concerns another company’s product.
2. Agree the test scope
We establish the relevant direction of loading, test arrangements, required records and calculations. Your quotation sets out the agreed work.
3. Carry out site testing
The agreed test applies a load and records the response at the selected positions. The product, setup and location remain part of the context for those results.
4. Supply the information
You receive recorded results, a written test report and the agreed load calculations for the project team to consider alongside the design.
Useful evidence, with the method made clear
The result needs to answer the question that prompted the test. An upward test, a downward test and a calculated capacity should be identified clearly, so your project team can see how a value was obtained.
We supply recorded results and a written report, with load calculations within the agreed scope. Tell us about any reporting requirement before the visit so it can be considered when the work is arranged.
One test is part of the wider foundation decision
Ground may vary across a site. A result at one position should not be treated as proof that every position is identical. The tested screw, loading direction, measured movement and any limitations all matter when the result is used.
Testing can inform a specification or support a project review. It does not by itself approve the building, replace the full foundation design or guarantee acceptance by Building Control.
If installation is also needed, see our ground screw foundation service. The installation and testing scopes are agreed for the project.