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
A case study and a warning to would-be developers
Creating four dwellings... after half a century of doing this job, why, oh why, is it so difficult?
Reform of the fire engineering profession
Fire Engineers Advisory Panel: Authoritative Statement, reactions and next steps.
Restoration and renewal of the Palace of Westminster
A complex project of cultural significance from full decant to EMI, opportunities and a potential a way forward.
Apprenticeships and the responsibility we share
Perspectives from the CIOB President as National Apprentice Week comes to a close.
The first line of defence against rain, wind and snow.
Building Safety recap January, 2026
What we missed at the end of last year, and at the start of this...
National Apprenticeship Week 2026, 9-15 Feb
Shining a light on the positive impacts for businesses, their apprentices and the wider economy alike.
Applications and benefits of acoustic flooring
From commercial to retail.
From solid to sprung and ribbed to raised.
Strengthening industry collaboration in Hong Kong
Hong Kong Institute of Construction and The Chartered Institute of Building sign Memorandum of Understanding.
A detailed description from the experts at Cornish Lime.
IHBC planning for growth with corporate plan development
Grow with the Institute by volunteering and CP25 consultation.
Connecting ambition and action for designers and specifiers.
Electrical skills gap deepens as apprenticeship starts fall despite surging demand says ECA.
Built environment bodies deepen joint action on EDI
B.E.Inclusive initiative agree next phase of joint equity, diversity and inclusion (EDI) action plan.
Recognising culture as key to sustainable economic growth
Creative UK Provocation paper: Culture as Growth Infrastructure.