An inspector’s view from the field
By E Shaw, New Homes Inspections — BSc (Hons), AICWCI, TechRPSA, NEBOSH Construction Cert
Key points
- Biggest red flag: signs of structural movement/instability (e.g., widening cracks, sloping floors, bowed walls, sagging rooflines).
- Most common issues: cosmetic/finish defects (annoying but fixable under warranty).
- Act fast: document with photos, reference standards (e.g., NHBC, Building Regs) and escalate; call a structural engineer if movement is suspected.
Why structure tops everything else
Scuffed paint? A squeaky stair? Missing mastic around a window? All irritating, all fixable. The structure—foundations, load‑bearing walls, roof framing—keeps the building standing, square and safe. If that’s compromised, costs escalate quickly and risk rises even faster.
Put bluntly: a loose door handle won’t make a home unsafe. A shifting foundation might.
Inspector’s note: Hairline shrinkage is normal in new builds as materials dry. It’s pattern, width and progression that matter. Straight cracks from corners, cracks that widen over time, partnered with sloping floors or sticking doors—that’s when my engineer radar lights up.
A real‑world snapshot
You step into a new living room and see a diagonal crack from a window corner down towards the skirting. On its own, it could be plaster shrinkage. But if that crack will take the edge of a £1 coin and the nearby floor feels uneven, the house could be telling you it’s moving. That’s not one to “keep an eye on” for months—get it assessed before you unpack the boxes.
[Image placeholder] Diagonal crack from window head to skirting. Caption: Measured 3–4 mm at widest point using a crack gauge; nearby floor recorded 12 mm over 2 m with a laser level.
The most common issues (usually not scary)
Structural faults are the biggest red flags, but they’re not the most common. Day to day, I log more finish and fit issues than anything else:
- Uneven plaster or visible paint runs
- Doors that catch or won’t latch cleanly
- Missing/poor sealant in kitchens and bathrooms
- Loose fixtures (sockets, handles, radiators)
- Small settlement cracks to walls or ceilings
These chip away at quality but rarely at safety. A good snagging list gets them sorted—ideally while your builder’s warranty covers the work.
What actually counts as a structural red flag?
These deserve priority attention and often specialist input if left untreated:
- Large or widening cracks in foundations, walls or ceilings
- Bowed/bulging walls (internal or external)
- Sagging/uneven rooflines or visibly deflected rafters
- Sloping, bouncy or spongy floors
- Sticking doors/windows plus nearby cracks (classic movement combo)
None of the above is a wait‑and‑see item. Movement tends to get worse, not better.
Inspector’s note: Record crack width/length and recheck at set intervals (e.g., 6–8 weeks). Progressive change = escalate.
Severity ladder (rule of thumb)
| Level | Typical signs | Action |
|---|---|---|
| Cosmetic | Hairline cracks (<1 mm), scuffs, minor snags | Note on snag list; routine fix under warranty |
| Monitor | 1–3 mm cracks with no pattern of movement | Record width/length, photograph, recheck in 6–8 weeks |
| Escalate | Widening cracks (>3 mm), sloping floors, bowed walls, dipped ridge, sticking doors/windows with cracks | Seek a structural engineer’s assessment; agree remedial plan before completion/retention release |
Mini case studies (experience in practice)
Case 1 — Diagonal crack + sloping floor (new build, 2‑storey)
- Problem: 3–4 mm diagonal crack from window head; 12 mm/2 m floor slope.
- Assessment: Likely differential settlement; monitored over 8 weeks with tell‑tales—movement continued.
- Outcome: Builder appointed structural engineer; localised underpinning and replaster.
- Cost band: £££–££££ (builder covered under warranty).
Case 2 — Bulging brickwork (rear elevation)
- Problem: Outer leaf bulging between openings; perished bed joints.
- Assessment: Insufficient wall ties and mortar degradation; borescope confirmed tie corrosion in places.
- Outcome: Tie replacement scheme, repointing, and lintel check; façade brought back plumb.
- Cost band: £££.
Case 3 — Damp patches + musty odour (ground floor)
- Problem: Localised damp staining on skirting; WME moisture readings 18–20%.
- Assessment: Blocked gullies and bridging of DPC by landscaping; no internal leak found.
- Outcome: Regrade paving to fall away, clear drainage, reinstate DPC clearance; timber dried, redecorated.
- Cost band: £–££.
Figures indicative; scope and costs vary by property and contractor.
Other red flags you shouldn’t ignore
Not structural, but they can lead to costly repairs and poor living conditions:
- Moisture & damp: stains, mould, musty odours, high meter readings
- Roofing defects: missing tiles, failed flashing, blocked gutters/downpipes
- Plumbing issues: leaks, low pressure, poor terminations or unsupported pipework
- Electrical concerns: damaged fittings, suspect wiring, missing RCD protection
- Drainage & grading: standing water near foundations, blocked gullies, poor fall away from the house
[Image placeholder] Thermal image of cold bridging at lintel. Caption: Localised heat loss; check insulation continuity and cavity trays.
What to do if you spot a red flag
- Document properly: clear photos, locations and descriptions in a written report.
- Reference standards: ask your inspector to cite relevant tolerances/guidance (e.g., NHBC Standards; Building Regulations Approved Documents).
- Escalate with evidence: send the report to the builder or warranty provider; keep all responses in writing.
- Bring in specialists for structure: a Chartered Structural Engineer assessment is money well spent when movement is suspected.
Free resource: Download my Cosmetic vs Structural: 20 Quick Checks (PDF checklist) — see the Checklist section below.
Methodology & scope (how I inspect)
- Non‑invasive visual survey with moisture meter, laser level, spirit level, binoculars, and thermal camera where helpful.
- Crack monitoring with tell‑tales for suspected movement; revisit schedule agreed where needed.
- Safety first: no destructive opening‑up; roof/loft access subject to safe access and weather.
- Escalation protocol: if indicators suggest instability, I recommend a structural engineer’s site assessment.
Standards & sources
Authoritative references I use and may cite in reports (region-specific):
NHBC (UK-wide new-build warranty context)
- NHBC Standards overview: https://www.nhbc.co.uk/technical/nhbc-standards
- NHBC Standards 2024 (full PDF): https://nhbcprod.blob.core.windows.net/shared/CC2981-NHBC-Standards-2024-aw-digital-version-lr-151223.pdf
- NHBC Technical Requirements (2025): https://www.nhbc.co.uk/homeowners/standards-technical-requirements
England — Approved Documents (statutory guidance)
- Approved Document A: Structure — https://www.gov.uk/government/publications/structure-approved-document-a
- Approved Document C: Site preparation and resistance to contaminants and moisture — https://www.gov.uk/government/publications/site-preparation-and-resistance-to-contaminates-and-moisture-approved-document-c
- Approved Document P: Electrical safety (dwellings) — https://www.gov.uk/government/publications/electrical-safety-approved-document-p
Wales — Approved Documents (Welsh Government)
- Collection page (all parts): https://www.gov.wales/building-regulations-approved-documents
Scotland — Building Standards Technical Handbook (Domestic)
- Section 1: Structure — https://www.gov.scot/publications/building-standards-technical-handbook-2022-domestic/1-structure/1-1-structure/
Northern Ireland — Technical Booklets (Department of Finance)
- Collection page (all booklets): https://www.finance-ni.gov.uk/articles/building-regulations-technical-booklets
- Booklet D (Structure) info: https://www.thenbs.com/PublicationIndex/documents/details?DocId=325286&Pub=DFP
BRE (Building Research Establishment) — crack assessment
- Insight article: Assessing cracks in houses — https://bregroup.com/insights/assessing-cracks-in-houses
- BRE Digest 251 (store page): https://bregroup.com/store/bookshop/assessment-of-damage-in-low-rise-buildings-progressive-foundation-movement-revised-1995-dg-251
FAQs
What’s the biggest red flag in a home inspection?
Structural movement or instability. Look for widening cracks, sloping floors, bowed walls, or a sagging ridge.
When should I call a structural engineer?
If cracks are widening, doors/windows are sticking and you can see related cracking, floors slope noticeably, or walls/rooflines are out of true.
Are hairline cracks normal in new builds?
Often, yes—materials dry and shrink. The concern is pattern and progression, not the existence of every fine crack.
Who pays for fixes on a new build?
Typically the developer during the snagging/defects period and under warranty, but confirm terms and time limits in your contract and warranty documents.
Can I ignore a damp patch if it’s small?
I wouldn’t. Moisture is a multiplier—left alone, it damages finishes, timber and indoor air quality.
About the author
E Shaw, BSc (Hons), AICWCI, TechRPSA, NEBOSH Construction Cert
New Homes Inspections — focused on movement, moisture and build quality.
- 100s+ new‑build and period inspections completed
- Specialist in structural movement diagnostics and damp investigation
- Public liability & professional indemnity insured
- Memberships: AICWCI , TechRPSA
Method summary: Visual, non‑invasive; measured crack widths; moisture/level checks; photographic evidence and clear defect schedules. Structural concerns → recommend CEng MICE/IStructE input.
Ready for a snagging survey?
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Inspections are visual and non‑invasive. Guidance here is informational and not a substitute for a site visit. Where indicators suggest structural movement or instability, I’ll recommend a structural engineer’s assessment.