27 Feb, 2026/ by Surveyor Local /Guides
Buyers who skip a property survey spend an average of £30,000 fixing problems a report would have caught before exchange, according to research by the HomeOwners Alliance. Yet because a survey is not a legal requirement in England and Wales, many still treat it as optional.
Getting a proper survey is worth the investment for the peace of mind alone. It either confirms the property is worth buying, or gives you the evidence to renegotiate the price, request repairs before exchange, or walk away before you are legally committed. A Level 2 HomeBuyer Report or Level 3 full building survey from a RICS-accredited chartered surveyor gives you that independent, expert assessment.
The most common defects found during a house survey
Roof defects
Surveyors check for missing or slipped tiles, damaged flashing around chimney stacks, deteriorating leadwork and signs of water ingress in the loft space. On older properties the felt underlay beneath the tiles can degrade over time, allowing moisture in even when the tiles above appear intact.
A full roof replacement typically costs between £5,000 and £15,000 depending on size and pitch. Any roof defect flagged on a survey should be followed up by a specialist roofer before exchange, as water ingress from above can cause cascading damage to timbers, ceilings and insulation.
Flat roof problems
Flat roofs have a shorter lifespan than pitched roofs, typically 10 to 20 years, and are more susceptible to pooling water, membrane failure and blistering. Surveyors check the covering for ponding or cracking and inspect the ceiling below for any water staining.
Replacement costs start from around £1,200 and rise considerably for larger areas. If a property has a flat roof section, it is worth establishing when it was last replaced and whether any warranty documentation exists.
Damp and moisture issues
Damp is one of the most common findings in UK property surveys and one of the easiest to miss during a viewing, hiding behind furniture, beneath carpets and within wall cavities. According to the government's English Housing Survey published in early 2025, 1.4 million dwellings in England had a damp problem in 2024.
A surveyor will use a moisture meter to check wall and floor readings and note any visible staining or mould growth. Treatment costs range from a few hundred pounds for minor condensation to over £5,000 for rising damp requiring a new damp-proof course.
Dry rot
Dry rot is triggered by excess moisture, creating conditions for the fungus Serpula lacrymans to take hold in timber. What makes it particularly destructive is its ability to spread rapidly across masonry and through walls, attacking previously dry timber well beyond the original source.
Treatment costs range from £1,000 to £5,000 for a contained outbreak but can exceed £20,000 in severe cases. A specialist timber report will be required before any mortgage lender will proceed.
Wet rot
Wet rot occurs when timber is exposed to sustained moisture, most commonly in sub-floor areas, loft spaces or around window and door frames, causing the wood to soften, darken and lose its structural integrity. Unlike dry rot, it does not spread beyond its moisture source.
Surveyors often find it in areas difficult to see during a viewing, such as beneath suspended timber floors or behind cladding. Treatment costs can reach several thousand pounds where structural timbers are involved.
Woodworm and timber infestation
Woodworm larvae burrow through timber for two to five years before emerging, leaving small round exit holes and a fine powder known as frass. In older properties some historic activity may no longer be active, but infestation in structural timbers such as roof rafters or floor joists is a more serious matter.
Professional treatment costs between £400 and £1,000 for a standard home, though structural repairs to compromised timber can add considerably more. Lenders increasingly require a specialist timber report where active infestation is noted on a survey.
Gutter and downpipe problems
When gutters and downpipes fail, water runs down external walls, saturating masonry and finding its way inside, making it one of the most common causes of penetrating damp in UK properties. Surveyors check for cracks, sagging, poor joints and overflow staining on external walls.
A full guttering replacement on a typical semi-detached house costs from around £400 to £800. The bigger risk is the cumulative damage to the building's fabric that failed guttering causes if left unaddressed over time.
Cracks, uneven floors and structural movement
Cracks and uneven floors can indicate subsidence, where the ground beneath a property shifts and the structure sinks unevenly, or heave, where expanding ground forces the foundations upwards. Hairline cracks in plaster are usually cosmetic, but wider or diagonal cracks around door frames or wall junctions warrant further investigation.
If significant movement is flagged, a structural engineer's report will be required before any lender proceeds. Remedial works such as underpinning can cost tens of thousands of pounds.
Asbestos
Asbestos was widely used in UK construction until it was banned in 1999 and turns up in a range of materials including roof tiles, floor tiles, Artex coatings, pipe lagging and soffit boards. A surveyor will flag potential evidence but will not test for it; that requires a specialist asbestos survey.
Undisturbed asbestos presents no health risk, but becomes hazardous when damaged or disturbed during renovation work. An initial asbestos survey costs from around £200, with professional removal starting at approximately £50 per square metre.
Electrical system faults
Outdated electrical installations are a common finding in properties built before 1970. Surveyors flag old consumer units, rubber-insulated or aluminium wiring, inadequate earthing and missing residual current devices. This is a visual assessment only, not a full electrical test.
A full electrical installation condition report (EICR) from a qualified electrician is the only way to confirm the system's precise state, costing between £150 and £300. Full rewiring of a three-bedroom house typically costs between £3,000 and £5,000.
Read our guide to electrics and old wiring in a house survey
Plumbing and heating problems
Leaking pipes, poorly installed sanitary ware and ageing boilers are regularly flagged on survey reports. Older properties may still have lead pipework in place, which presents a health concern and will need replacing. Boilers over 15 years old are approaching or past the end of their expected lifespan.
Boiler replacement typically costs between £2,000 and £4,000. Where drainage concerns are flagged, a CCTV drain survey, typically costing around £250, is often recommended and can also support a price negotiation before exchange.
Spray foam insulation
Spray foam insulation is present in around 250,000 UK homes, many fitted under government-backed energy efficiency schemes, but its presence now creates serious problems for buyers trying to secure a mortgage. Closed-cell foam can trap moisture around roof timbers, obstruct proper inspection of the roof structure and accelerate timber decay.
Many lenders will decline to proceed until a specialist assessment has been carried out. Where removal is required, costs start at around £3,200 for a three-bedroom detached house.
Japanese knotweed
Japanese knotweed has roots capable of reaching 3 metres below ground and 7 metres horizontally, and its presence on or near a property is a significant concern for lenders and buyers alike. Most lenders will initially decline to lend where it is identified within 3 metres of the boundary, though many will reconsider where a 10-year insurance-backed treatment plan from a Property Care Association-accredited specialist is in place.
There is also a legal dimension: under the Wildlife and Countryside Act 1981 it is an offence to allow knotweed to spread to neighbouring land, and sellers who fail to disclose it on the TA6 form risk legal action for misrepresentation.
Poor insulation and energy efficiency
Inadequate insulation, poorly fitted doors and windows, blocked air bricks and poor circulation are all commonly noted on survey reports. Government figures show that only 42% of homes with a loft have insulation above 200mm thickness, and the average cost to bring a property up to EPC band C is £7,480.
Buyers should factor these costs into their offer price, particularly on older or poorly maintained properties where multiple upgrades may be needed.
Missing certificates and planning documentation
A survey can flag the absence of documentation that is just as important to a purchase as the building's physical condition. Building regulations certificates confirm that extensions and alterations met an approved standard; electrical and gas certificates confirm domestic systems are safe. Missing paperwork can delay or derail a transaction and some lenders will not proceed without it.
In many cases indemnity insurance can cover the absence of paperwork, but this is a matter for your conveyancer to advise on rather than something to overlook during the buying process.
What to do when your survey flags a problem
A problem identified on a survey is not automatically a reason to abandon the purchase. The key is understanding whether the issue is cosmetic, manageable with routine maintenance, or a serious structural or legal concern. Survey reports use a condition rating system to grade the severity of each finding and most will indicate whether specialist investigations are recommended.
If significant issues are found, the most practical next step is to obtain quotes from specialist contractors before deciding how to proceed. With accurate repair cost estimates in hand you can return to the seller and either negotiate a price reduction, request that works are completed before exchange, or reconsider the purchase altogether. You are under no legal obligation to proceed until contracts have been exchanged.
If your survey has flagged any of these issues, our guide on what to do when your house survey reveals problems sets out your options.
Find a chartered surveyor near you
If anything on this page has flagged a concern about a property you are buying, the right next step is an independent survey from a RICS-accredited chartered surveyor.
Surveyor Local works with a nationwide panel of qualified surveyors who can give you a clear, impartial picture of the property's condition before you commit to anything.
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Frequently asked questions about house surveys
Do I need a survey if I am buying with cash?
Yes. The fact that you do not have a mortgage lender requiring a valuation makes an independent survey more important, not less. Without a lender's involvement, nobody else is checking the property's condition on your behalf. A survey is the only way to get an independent, professional assessment of what you are buying before you commit.
Which survey is best for an older property?
For most properties built before the 1930s, a Level 3 full building survey is the better choice. Older properties are more likely to have structural quirks, original materials that behave differently to modern equivalents, and a longer history of alterations — all of which benefit from a more detailed inspection than a Level 2 HomeBuyer Report provides.
How long does a house survey take?
A Level 2 HomeBuyer Report typically takes two to four hours on site for a standard property. A Level 3 full building survey can take four to eight hours depending on the size and complexity of the property. The written report is usually delivered within five to ten working days of the inspection.
What happens if a survey finds a serious problem?
You have three options: negotiate a reduction in the asking price to reflect the cost of repairs, ask the seller to carry out the remedial work before exchange, or walk away from the purchase entirely. You are under no legal obligation to proceed before contracts are exchanged, and a serious survey finding is a legitimate reason to renegotiate or withdraw.
Can I use a survey to renegotiate the price?
Yes, and this is one of the most practical uses of a survey report. If the surveyor identifies defects that were not apparent during viewings, you can obtain quotes from specialist contractors and use those figures to support a price reduction request. Sellers are generally aware that the same issues will likely appear on any buyer's survey, which gives you reasonable leverage.
Who pays for the survey if the sale falls through?
The buyer pays for the survey regardless of whether the sale completes. Survey costs are not recoverable if a transaction falls through, which is one reason buyers sometimes hesitate to commission one early. However, discovering a serious problem before exchange is far less costly than discovering it after completion.