Trial pit
A trial pit (also known as a test pit) is a type of intrusive ground investigation that is used as a means of determining the condition of the ground, typically before beginning construction works.
Trial pits are commonly used to investigate shallow ground conditions to develop an understanding of the profile of soils within the ground. They can be particularly useful where buried structures, variable conditions or contamination is suspected or needs further investigation.
They can be excavated by hand or using a backhoe excavator, generally to a depth of up to 3.5-4.5 m. If a trial pit is deeper than 1.2 m and is intended to be entered by people, it should be made secure against the possibility of structural collapse.
Trial pits (or trenches) can be more cost-effective than boreholes but they cannot reach the same depth. Trial pits can also excavated relatively quickly. However, they can cause significant surface disturbance and it can be difficult to properly fill excavations when the pit is no longer needed.
[edit] Related articles on Designing Buildings Wiki
Featured articles and news
Homes England creates largest housing-led site in the North
Successful, 34 hectare land acquisition with the residential allocation now completed.
Scottish apprenticeship training proposals
General support although better accountability and transparency is sought.
The history of building regulations
A story of belated action in response to crisis.
Moisture, fire safety and emerging trends in living walls
How wet is your wall?
Current policy explained and newly published consultation by the UK and Welsh Governments.
British architecture 1919–39. Book review.
Conservation of listed prefabs in Moseley.
Energy industry calls for urgent reform.
Heritage staff wellbeing at work survey.
A five minute introduction.
50th Golden anniversary ECA Edmundson apprentice award
Showcasing the very best electrotechnical and engineering services for half a century.
Welsh government consults on HRBs and reg changes
Seeking feedback on a new regulatory regime and a broad range of issues.
CIOB Client Guide (2nd edition) March 2025
Free download covering statutory dutyholder roles under the Building Safety Act and much more.
Minister quizzed, as responsibility transfers to MHCLG and BSR publishes new building control guidance.
UK environmental regulations reform 2025
Amid wider new approaches to ensure regulators and regulation support growth.
BSRIA Statutory Compliance Inspection Checklist
BG80/2025 now significantly updated to include requirements related to important changes in legislation.