This page provides general practical guidance and does not replace project-specific legal, engineering, planning, ecological, asbestos or waste advice.
The short answer
Opening-up works involve carefully exposing concealed elements of an existing structure — beams, bearings, joists, lintels, wall construction, floor build-up, foundations, hidden steelwork or structural interfaces — so that the actual condition can be recorded and assessed. The purpose is investigative: to confirm or disprove assumptions before a structural engineer or designer finalises the subsequent solution. Opening-up itself is not necessarily the final structural alteration.
Why it matters
Drawings and records do not always accurately represent what was actually built. Structural solutions are designed against the actual construction, not the assumed construction. Where the actual condition differs from the assumption — different beam sizes, unexpected supports, additional wall layers, unknown foundations — the engineered solution may need to change. Discovering this after structural work has begun is more disruptive and costly than discovering it during a controlled opening-up phase.
Information that may be needed
Existing drawings, structural calculations, survey information and any previous investigation reports may be relevant. Where an engineer has requested opening-up before issuing final structural drawings, their brief for the investigation should be confirmed before the scope is agreed.
What can affect the scope
The extent of opening-up, the elements to be exposed, the method of exposure, the condition required for inspection, the extent of making good or reinstatement, and whether temporary support is required during the investigation can all affect the scope. The engineer's brief for the investigation should drive the scope — not a general assumption about what needs to be seen.
When specialist input may be needed
A structural engineer is required to brief the investigation, assess the findings and issue revised structural drawings where the actual condition differs from the assumption. Where unexpected conditions are found during opening-up, the engineer should be consulted before the scope is extended.