Alterations can add useful space, but they also change loads, ventilation, drainage and weathering. A rear extension introduces junctions with the original wall and roof. A loft conversion alters roof structure, insulation and escape arrangements. Removing a wall or chimney breast requires loads to be supported elsewhere.
A surveyor assesses visible condition and signs that further investigation is needed. The inspection does not expose steel beams, verify every structural calculation or certify building-regulation compliance. Planning, building control, party-wall procedures and lease consent are separate matters for documentary and legal enquiry.
Structural clues
Cracking at junctions, sagging ceilings, deflected floors, distorted openings and incomplete bearings may raise concern. Some minor cracking between old and new construction is common because materials and foundations move differently. Significance depends on pattern, extent and evidence of change rather than the mere presence of a line.
Roof and weathering junctions
Extension abutments, box gutters, rooflights and parapets are common leak points. Loft conversions can leave restricted roof voids and concealed insulation. A dry inspection does not rule out intermittent water entry, and internal linings prevent confirmation of hidden flashings, membranes and structural connections.
Removed walls and chimneys
Load-bearing walls and chimney breasts may support masonry, floors or roofs. Visible boxing may contain a beam, but its size, bearing and connection cannot be confirmed by sight. Where records are absent and consequences are material, structural-engineer review or agreed opening-up may be appropriate.
Permissions and party walls
Building regulations approval is different from planning permission, and either may be relevant. Work to shared structures or excavation near neighbours may engage the Party Wall etc. Act. Your conveyancer should review approvals, completion documents, indemnity proposals and ownership issues; the surveyor should avoid giving a legal determination.
Before exchange
Request drawings, structural calculations, approvals, completion certificates, warranties and contractor details. Compare records with the layout on site. Absence of paperwork does not by itself prove poor construction, while paperwork does not guarantee defect-free work. Resolve important uncertainty through proportionate inspection rather than assumption.
Where an extension is close to a boundary, confirm ownership and access for maintenance. Loft rooms need safe stairs, ventilation and suitable services as well as structure. Ask who designed and supervised work and whether later modifications departed from approved drawings. Indemnity insurance, if proposed, addresses a legal risk and does not confirm physical adequacy. Also check whether altered drainage or heating serves the new space adequately under normal use.
- Compare the current layout with approved drawings
- Locate visible supports and altered load paths
- Inspect every old-to-new weathering junction
- Separate legal paperwork from physical condition
Advice for your property
Get the right professional inspection
Online guidance is useful, but it cannot account for the construction, condition and history of an individual property. Tell us what you are buying or need valued and we will explain the appropriate service.
Authoritative sources and further reading
The guide is general information, not property-specific, structural, legal, tax or financial advice. Source pages can change; consult the relevant professional for your circumstances.