Hidden problems a surveyor can spot before you buy
When you're buying a home, it’s easy to fall in love with the layout, the light, the garden, or that big open plan kitchen. But beneath the surface, there could be problems waiting to reveal themselves after you’ve moved in.
That’s where a residential surveyor comes in. They're trained to look past the freshly painted walls and into the bones of the property. Here are five serious issues a good surveyor can uncover that most buyers simply won’t spot themselves.
Hidden Damp and Moisture Ingress
What you might see: Nothing, or maybe a slightly musty smell.
What the surveyor sees: Elevated moisture readings behind plaster, tell tale salt deposits, or paint that’s concealing recurring damp.
Why it matters:
Damp isn't just unpleasant—it causes rot in timbers, degrades plaster, ruins finishes, and encourages mould. Left untreated, it can be a serious structural problem. A surveyor uses specialist equipment (like a Protimeter damp meter) to measure moisture levels in walls, ceilings and floors even when surfaces appear dry.
Common causes surveyors look for:
Faulty damp proof course (especially in older homes)
Blocked or broken gutters and downpipes
Bridged cavity walls
Poor external ground levels sloping towards the house
Real world impact:
If damp is found in a Victorian terrace, the remedy could involve stripping plaster, injecting chemical damp proofing, and re-rendering, costing £3,000–£6,000 easily. Spotting this during a survey allows you to renegotiate or plan ahead.
Roofing Issues That Aren’t Visible from Ground Level
What you might see: A nice, clean loft or some new tiles.
What the surveyor checks: Roof structure, sarking, flashing, soffits, ridge tiles, and chimney stability using ladders or pole mounted cameras if needed.
What they’re looking for:
Sagging or deflected rafters
Damaged or slipping tiles and slates
Poor ventilation (which causes condensation)
Flat roofs with pooling water or cracking felt
Flashings that have failed around chimneys or valleys
Hidden signs:
Even if the ceiling doesn’t show water stains, the roof could be slowly leaking into the void, degrading timbers and insulation. In some cases, rot can be present in purlins or joists, unseen unless accessed from the loft.
Why it matters:
Replacing a pitched roof costs £7,000–£12,000+ depending on the size. Minor repairs might be £300–£1,000—but only if caught early. Surveyors know the warning signs and can estimate how much life a roof has left.
Subsidence or Structural Movement
What you might see: A few cracks by the windows or doors.
What the surveyor assesses: Type, location, pattern, and severity of any cracking, plus nearby trees, drainage conditions, and the age of the property.
Key red flags:
Diagonal cracks wider than 5mm, especially around openings
Doors or windows that stick due to warped frames
Sloping floors in one part of the house
Previous underpinning or evidence of movement
Causes surveyors evaluate:
Clay soil shrinkage (especially in summer)
Tree roots too close to foundations
Leaking underground drains
Poorly executed extensions or alterations
Why it matters:
Subsidence is serious. It often means insurance difficulties, expensive underpinning (£10,000–£50,000), and even potential legal issues if the seller failed to disclose it.
A surveyor won't just say “cracks noted”—they’ll explain whether it’s historic (and stable) or ongoing (and serious), and whether a structural engineer’s report is needed.
Outdated or unsafe services (electrics, plumbing, heating)
What you might see: A working light switch and hot running water.
What the surveyor notices: Signs of ageing systems or non compliant installations.
What surveyors check:
Fuse box (consumer unit) condition and type
Wiring age (e.g. rubber or lead sheathed cables are outdated)
Boiler make, model, and service history
Pipework material (e.g. steel or lead pipes are outdated)
Signs of leaks around tanks, joints or radiators
Common findings:
No RCD protection in consumer unit (a safety issue)
Boiler older than 15 years and nearing end of life
Gravity fed plumbing that results in poor pressure upstairs
Evidence of DIY plumbing (unsupported pipes, poor joins)
Why it matters:
A full rewire: £4,000–£7,000+
New boiler: £2,000–£3,000
Plumbing upgrades: variable, but potentially several thousand
These systems might appear to function, but replacing them can be disruptive and expensive. A surveyor’s advice lets you factor this into your offer—or budget realistically.
Legal and boundary concerns that could trip you up
What you might assume: “That driveway, shed or extension is part of the sale.”
What a surveyor checks: Whether the physical boundaries match the legal ones, and whether outbuildings or extensions are properly constructed and approved.
What they flag:
Encroachments (neighbour's fence or wall on your land)
Shared driveways or rights of access not properly documented
Structures built too close to boundaries (a planning red flag)
Extensions with poor workmanship or no building control sign off
Real examples:
A conservatory added without proper footings
A garden office that violates permitted development limits
A loft conversion without a completion certificate
Why it matters:
These can lead to disputes, insurance complications, or mortgage lender concerns. In worst case scenarios, illegal structures might have to be demolished, or you could be liable for neighbour disputes that pre date your ownership.
A surveyor will recommend if your solicitor needs to dig deeper, saving you time, stress, and unexpected legal costs.
Trust the surveyor’s eye
Estate agents don’t have to point out potential problems, they work for the seller. Your surveyor works for you. They bring technical knowledge, impartiality, and years of experience to spot what most of us can’t.
So if you’re on the fence about getting a survey, or tempted to just go with the cheapest onedon’t. Spend wisely and choose a reputable RICS registered surveyor who will give you a full, clear picture of the property’s condition.
Because once you’ve exchanged contracts, those hidden problems become your problems.