What an upward pull test tells you
A foundation may need to resist forces that try to lift it, as well as carry the weight above. A ground screw pull test applies an upward load and records how the screw responds in the ground at the selected test position.
You may also see this described as tensile, tension, pull-out or uplift testing. The important point is the direction and purpose of the test: the screw is being loaded upwards. It is a different exercise from physically pushing a ground screw downwards in a compression test.
The useful evidence is more than a single headline load. The method and measured response give the project team the context needed to consider the result against the foundation requirement.
Agreeing the test before we arrive
A useful test starts with a clear brief. If your engineer has already requested particular information, share that request. If you are exploring the foundation options, tell us what you intend to build and we will discuss what needs to be established.
The screw and location
We review the proposed or installed screw, its available product information and the test area. Access, nearby features and any known variation in ground inform the arrangements.
The purpose and loading
The target, loading approach and stopping criteria need to match the project question. A check at a specified load and a test investigating a limiting response serve different purposes.
The record you need
We agree the written report and any load calculations. Tell us who will use the information, so their requirements can be considered before the test is arranged.
How the pull testing visit works
1. Confirm the position
The test location and relevant screw details are identified against the agreed scope. Whether the test concerns a trial screw or an existing installation is settled beforehand.
2. Apply an upward load
The testing arrangement applies a controlled upward force to the screw. The loading follows the agreed method rather than an assumed target for every site.
3. Record the response
Load and movement are recorded as required by the test. Observations and the arrangement provide context for interpreting the results.
4. Provide the report
Recorded results and a written test report are supplied, together with the agreed load calculations. The project team can then review them against the design requirements.
We discuss access and preparation when planning the visit, including what happens to the tested screw afterwards. Contact us before making assumptions about keeping a tested screw as a working foundation.
Pull testing without an installation contract
You do not have to buy a complete foundation installation from JustBases to enquire about testing. We offer testing as a separate service, including for ground screws supplied or installed by another company.
This can help an installer or building team obtain site evidence before committing to the next stage. Tell us which product is involved, whether it is already installed and what information you need. We then review compatibility with the proposed test arrangement and agree the scope.
Where JustBases is also installing the foundation, the test and installation can be discussed together. The quotation confirms what is included and the sequence of work.
A calculation is identified as a calculation
JustBases also offers load calculations. Where appropriate for the agreed method, pull-test results can inform a calculated compression capacity.
That does not turn an upward test into a physical downward test. The calculation needs a suitable basis, with its assumptions and applicability considered for the project. A universal multiplier between tension and compression would not describe our service accurately.
For direct downward testing and a fuller explanation of calculated values, see ground screw compression load testing.
Using pull test results responsibly
The result belongs to a particular test: a specific screw, location, setup and loading direction. Ground conditions can change across a site, and an uplift result does not independently establish the downward or sideways performance of every foundation point.
The written report and calculations support the foundation decision. They do not automatically approve the complete structure or guarantee Building Control acceptance. If a particular submission or designer’s requirement applies, let us know at the start.
Lateral testing, torsional testing and recorded installation torque are available by arrangement for specialist projects. They are separate considerations rather than standard additions to a pull test.