Common Survey Issues That Delay House Sales

When a buyer commissions a survey on your property, the surveyor's job is to identify defects, assess risks, and flag anything that might affect the property's value or safety. For sellers, this is often the most nerve-wracking part of the transaction. A survey that raises significant concerns can lead to renegotiation, delays, or the buyer pulling out entirely.

Understanding what surveyors look for — and which issues are most likely to cause problems — puts you in a stronger position. This guide covers the ten most common issues found during residential property surveys in England and Wales, with practical advice on what each one means for your sale and what you can do about it.

Summary of common survey issues

The table below provides an overview of the most frequently raised survey issues, their typical cost to remedy, and how likely each one is to derail or significantly delay your sale.

These cost ranges are indicative and based on typical UK residential properties. Actual costs will vary depending on the size of the property, the extent of the problem, and regional labour rates.

1. Damp and moisture problems

Damp is the single most common issue flagged in UK property surveys. Surveyors use moisture meters and visual inspection to identify three main types: condensation, rising damp, and penetrating damp. Each has different causes, different costs to treat, and a different impact on your sale.

What surveyors look for

The surveyor will take moisture readings from internal walls, check for visible signs such as tide marks, staining, peeling wallpaper, mould growth, and salt deposits (efflorescence). They will also inspect external elements — gutters, downpipes, render, pointing, and ground levels — for defects that could allow water ingress. If elevated readings are found, the surveyor will typically recommend a specialist damp investigation.

Impact on the sale

Condensation is the least serious form and rarely derails a sale, though visible mould can reduce offers by £1,000 to £3,000. Rising damp and penetrating damp are more significant. A chemical damp-proof course for rising damp typically costs £1,500 to £4,000, and buyers will seek a corresponding reduction or request that treatment is completed before exchange. Mortgage lenders may impose retentions or require treatment as a condition of lending.

What you should do

Address visible condensation and mould before marketing. For structural damp, commission an independent report from a PCA-accredited specialist. Having your own diagnosis and treatment quotes ready prevents the buyer from overestimating the cost. For detailed guidance, see our guide on selling a house with damp.

2. Roof defects

Roof problems are among the most expensive survey findings and are flagged frequently, particularly on older properties. Surveyors inspect the roof covering from ground level (and internally from the loft space where accessible) but do not typically climb onto the roof.

What surveyors look for

Common roof issues include missing, cracked, or slipped tiles or slates, deteriorated lead flashings around chimneys and abutments, sagging ridge lines indicating structural movement in the roof timbers, failed or blistered flat roof coverings, and blocked or leaking gutters and downpipes. In the loft, the surveyor checks for daylight penetration, signs of water ingress, the condition of timbers, and the adequacy of insulation.

Impact on the sale

Minor repairs such as replacing a few slipped tiles or clearing gutters cost £200 to £500 and are unlikely to affect the sale significantly. A full re-roofing of a typical three-bedroom semi-detached house costs £5,000 to £15,000, and buyers will negotiate hard on this. Mortgage lenders take roof defects seriously because they affect the habitability and insurability of the property. A lender may impose a retention equal to the estimated repair cost or refuse to lend until the work is done.

What you should do

Before marketing, have obvious issues like blocked gutters and missing tiles addressed — these are low-cost repairs that remove easy targets for the surveyor. If you know the roof is near the end of its life, obtain quotes from reputable roofing contractors so you can negotiate from a position of knowledge rather than reacting to the buyer's estimates.

3. Subsidence and structural movement

Subsidence is one of the most feared survey findings, and for good reason. Active structural movement can make a property unmortgageable and reduce its value significantly. However, a history of resolved subsidence is far more common than active movement, and thousands of properties with subsidence histories are sold every year.

What surveyors look for

Surveyors examine cracking patterns carefully. Diagonal cracks wider than about 5mm, particularly around door and window openings, may indicate structural movement. The surveyor will note whether cracks appear to be historic (filled and decorated over) or recent (fresh plaster cracking, distortion of door or window frames). They will also look for external signs such as bulging walls, leaning chimneys, and gaps between extensions and the main building.

Impact on the sale

Active subsidence is a potential deal-breaker. Most mainstream mortgage lenders will not lend on a property with active movement, limiting your buyer pool to cash purchasers who will typically seek a discount of 10 to 25 per cent or more. Resolved subsidence with a certificate of structural adequacy is less problematic — most lenders will consider lending, though some may require specialist insurance. Underpinning alone costs £5,000 to £50,000 depending on the extent, and monitoring runs for at least 12 months.

What you should do

If your property has a history of subsidence, gather all documentation: the certificate of structural adequacy, monitoring reports, underpinning certificates, and insurance claim records. Disclose the history honestly on the TA6 form. If you suspect active movement, commission a structural engineer's report before listing. Our guide on selling a house with subsidence covers this in full detail.

4. Outdated electrics

Electrical safety is a significant concern for surveyors, buyers, and mortgage lenders. Properties with wiring that has not been updated for several decades are routinely flagged, and this is one of the more common findings on properties built before the 1980s.

What surveyors look for

The surveyor will check the consumer unit (fuse box) for age and type. An old-style fuse box with rewirable fuses rather than modern MCBs (miniature circuit breakers) and an RCD (residual current device) is a red flag. They will also note visible wiring types — rubber-insulated or lead-sheathed wiring indicates pre-1960s electrics that are almost certainly due for replacement. The surveyor does not carry out electrical testing, but they will recommend an Electrical Installation Condition Report (EICR) if they have concerns.

Impact on the sale

A full rewire of a typical three-bedroom house costs £3,000 to £6,000 and is disruptive, requiring access to all rooms and redecoration afterwards. Buyers will factor this into their offer. Some mortgage lenders will not lend on properties with electrics rated as "unsatisfactory" on an EICR (Category C1 or C2 codes), and may require remedial work before releasing funds. A partial upgrade, such as replacing the consumer unit and adding RCD protection, costs £300 to £600 and may be sufficient to satisfy a mortgage lender.

What you should do

If your property has not been rewired in the last 30 years, consider commissioning an EICR before listing. This costs £150 to £300 and gives you a clear picture of the electrical condition. If the report identifies urgent issues (C1 codes), addressing them before marketing removes a significant obstacle. At minimum, upgrading to a modern consumer unit with RCD protection is a relatively low-cost improvement that surveyors and lenders notice.

5. Japanese knotweed

Japanese knotweed is one of the most problematic survey findings for sellers because of its effect on mortgage availability. Even the presence of knotweed on neighbouring land within seven metres of the property can affect your sale.

What surveyors look for

Surveyors are trained to identify Japanese knotweed by its distinctive characteristics: hollow, bamboo-like stems with purple speckles, shield-shaped leaves, and clusters of small white flowers in late summer. In winter, dead brown canes remain visible. The surveyor will also note any knotweed on adjacent land and record how close it is to the property boundary. RICS classifies knotweed risk into four categories based on proximity, with Category 4 (within the boundary or within seven metres) being the most serious.

Impact on the sale

Most mainstream mortgage lenders will not lend on a property with Japanese knotweed unless a professional management plan from a PCA-accredited contractor is in place, along with an insurance-backed guarantee. Treatment plans typically last three to five years and cost £2,000 to £15,000 depending on the extent of the infestation. Without a management plan, you are limited to cash buyers, who will negotiate heavily on price.

What you should do

If you know or suspect knotweed is present, arrange a professional survey and treatment plan before listing. The TA6 form asks specifically about Japanese knotweed, and you must disclose it honestly. Having a management plan with an insurance-backed guarantee in place before the buyer's survey significantly increases the chances of a successful sale. See our detailed guide on selling a property with Japanese knotweed.

6. Asbestos-containing materials

Asbestos was widely used in UK construction from the 1950s to the mid-1980s and is still present in many homes. It was used in a variety of products including cement roofing sheets, artex ceiling coatings, floor tiles, insulation boards, and pipe lagging. Any property built or renovated before 2000 could contain asbestos-containing materials (ACMs).

What surveyors look for

Surveyors note materials that they suspect may contain asbestos based on their appearance, age, and location. Common areas include garage and outbuilding roofs (corrugated cement sheets), textured ceiling coatings, soffit boards, and boiler flue pipes. The surveyor cannot confirm the presence of asbestos through visual inspection alone — laboratory analysis of a sample is required for a definitive result. If ACMs are suspected, the surveyor will recommend an asbestos survey.

Impact on the sale

Undisturbed asbestos in good condition is generally considered manageable and does not need to be removed. The Health and Safety Executive (HSE) advises that asbestos materials in good condition and unlikely to be disturbed are best left in place and managed. However, if removal is needed — for example, because the buyer plans renovations or the material is damaged — costs range from £500 for a small area to £10,000 or more for extensive removal by a licensed contractor. Buyers may renegotiate by £1,000 to £5,000 depending on the extent.

What you should do

If you know or suspect your property contains asbestos, disclose it on the TA6 form. If you have had an asbestos survey or management plan, provide a copy to your solicitor. For a full overview of your options, read our guide on asbestos and selling a house.

7. Timber defects: woodworm, wet rot, and dry rot

Timber problems are common in older UK properties and encompass three main types of defect: woodworm (insect attack), wet rot, and dry rot. The severity ranges widely, from minor cosmetic damage to structural failure requiring major remediation.

What surveyors look for

For woodworm, surveyors look for small round exit holes (typically 1 to 2mm for common furniture beetle), bore dust (frass) below affected timbers, and weakened or crumbling wood. For wet rot, signs include soft, spongy timber, darkened or discoloured wood, and paint that flakes or peels from timber surfaces. Dry rot is the most serious and is identified by characteristic large cracks along and across the grain, white or grey cotton-wool-like mycelium growth, and mushroom-like fruiting bodies. The surveyor will pay particular attention to floor timbers, roof timbers, window frames, and any areas where timber is in contact with damp masonry.

Impact on the sale

Historic woodworm that is no longer active (evidenced by old, unfrassed holes with no fresh bore dust) is a cosmetic issue costing very little to address. Active woodworm treatment costs £500 to £2,000 depending on the extent. Wet rot repairs are typically localised and cost £200 to £2,000 — replacing a rotted window frame, for example, is a straightforward repair. Dry rot is far more serious because the fungus can spread through masonry and requires comprehensive treatment: stripping out affected timbers, treating surrounding masonry with fungicide, and replacing structural elements. Dry rot remediation costs £2,000 to £20,000 or more and can be a deal-breaker if widespread.

What you should do

If you are aware of timber problems, obtain a specialist timber survey from a PCA-accredited contractor. Treatment certificates with transferable guarantees are particularly valuable to buyers. If previous treatment was carried out, locate the guarantee — if it has been lost, your solicitor can arrange indemnity insurance as an alternative.

8. Missing building regulations certificates

If your property has had structural alterations, extensions, loft conversions, window replacements, or other notifiable work, the buyer's solicitor will ask for building regulations completion certificates. Missing certificates are one of the most frequently raised conveyancing issues and cause delays in a large number of transactions.

What surveyors look for

Surveyors note any visible alterations or additions to the property and will comment on whether they appear to have been carried out to an acceptable standard. They may flag work that looks as though it may not have had building regulations approval — for example, a loft conversion with inadequate headroom, a bathroom without proper ventilation, or a structural wall that appears to have been removed without a supporting beam. The surveyor's role is to flag concerns; the buyer's solicitor then requests the certificates.

Impact on the sale

Missing building regulations certificates do not usually stop a sale but they create delays while the issue is resolved. A retrospective regularisation application to building control costs £250 to £800 and takes four to eight weeks. Alternatively, indemnity insurance can be purchased for £100 to £300 and is accepted by most mortgage lenders as an alternative. However, indemnity insurance only covers the financial risk of enforcement action — it does not confirm that the work was done to a safe standard.

What you should do

Before listing, check whether you have building regulations certificates for all notifiable work carried out during your ownership. If certificates are missing, speak to your solicitor about whether regularisation or indemnity insurance is the better route. For a comprehensive breakdown, see our guide on missing building regulations certificates.

9. Boundary issues

Boundary problems are less about the physical condition of the property and more about legal certainty, but they are frequently raised during the survey and conveyancing process. Unclear or disputed boundaries can cause significant delays and, in the worst cases, deter buyers entirely.

What surveyors look for

The surveyor notes the general boundary features — fences, walls, hedges — and may comment on whether the physical boundaries appear to correspond with the property's title plan. They do not carry out a formal boundary survey, but they may flag obvious discrepancies such as structures that appear to encroach onto neighbouring land, shared access arrangements that are unclear, or fence lines that do not align with what might be expected from the property's footprint.

Impact on the sale

Minor boundary uncertainties can usually be resolved through a statutory declaration or indemnity insurance at modest cost (£200 to £500). Active boundary disputes are more problematic. A buyer who discovers an unresolved dispute with a neighbour may withdraw rather than inherit the problem. Formal boundary determination by a chartered land surveyor costs £500 to £2,000, and legal resolution of a dispute can cost considerably more. The TA6 form asks specifically about boundary disputes, and honest disclosure is essential.

What you should do

Resolve any known boundary disputes before listing where possible. If a dispute cannot be resolved, disclose it fully on the TA6 and prepare documentation showing the history of the issue and any correspondence with the neighbour. Some buyers, particularly cash buyers, will proceed with full knowledge of a dispute if the price reflects the risk.

10. Drainage problems

Drainage issues are common in UK properties of all ages and can range from a blocked drain that is quickly cleared to a collapsed underground pipe requiring excavation and replacement. Drainage problems are particularly significant because they can affect both the property and neighbouring properties.

What surveyors look for

The surveyor inspects visible drainage elements including manhole covers, gullies, downpipe connections, and any areas of standing water or waterlogged ground. They may lift accessible manhole covers to check the condition of the drainage runs. Signs of problems include slow-draining sinks or baths, unpleasant smells, damp patches near drain runs, and cracked or displaced manhole covers. The surveyor will recommend a CCTV drainage survey if they suspect problems below ground.

Impact on the sale

Clearing a blocked drain costs £75 to £300 and is a minor issue. Repairing or replacing a section of collapsed drain costs £1,000 to £4,000. If the drainage system is shared with neighbouring properties (which is common for pre-1937 drains now adopted by the water company), responsibility for repairs depends on whether the drain is a public or private sewer. Since the transfer of private sewers to water companies in 2011, many shared drains are now the water company's responsibility, which can simplify matters. Buyers will want clarity on drainage responsibilities, and unresolved problems can lead to renegotiation of £1,000 to £5,000 or more.

What you should do

If you are aware of drainage problems, consider commissioning a CCTV drainage survey before listing. This costs £150 to £400 and provides a clear picture of the drainage condition. Having the report available to share with the buyer demonstrates transparency and prevents delays during conveyancing. Check whether any shared drains are now the water company's responsibility — a drainage search from your solicitor will confirm the position.

What happens after the buyer's survey

Once the buyer receives their survey report, the sale enters a negotiation phase. The buyer may accept the findings and proceed at the agreed price, renegotiate based on the cost of remedial work, request that you carry out repairs before exchange, or withdraw from the sale entirely.

How you respond to the buyer's survey findings is critical. Reacting defensively or refusing to engage will often push the buyer towards withdrawal. A constructive approach — acknowledging the findings, providing your own evidence or reports, and being willing to negotiate — keeps the sale alive. For a step-by-step guide to handling this stage, see our guide on what happens after the buyer's survey.

If the buyer seeks a price reduction, they should provide evidence for the amount they are requesting. You are under no obligation to agree. Having your own quotes and specialist reports gives you a factual basis for negotiation rather than relying on the buyer's estimates, which are often higher than the actual cost of work. Our guide on renegotiation after a survey explains the process in detail.

How to prepare for the buyer's survey

As a seller, you cannot control what the surveyor finds, but you can control how prepared you are. The following steps will put you in the strongest possible position:

1. Walk your property with a critical eye. Before listing, look at your property the way a surveyor would. Check for visible damp, cracked render, missing tiles, blocked gutters, and any obvious defects. Addressing low-cost issues before marketing reduces the number of items the surveyor flags.
2. Gather documentation for past work. Collect building regulations certificates, planning permissions, electrical certificates, gas safety records, damp treatment guarantees, and any specialist reports. Your solicitor will need these during conveyancing, and having them ready avoids delays.
3. Commission targeted specialist reports. If you know your property has specific issues — a history of subsidence, suspected asbestos, or Japanese knotweed on or near the boundary — getting your own specialist reports in advance is one of the most effective things you can do. It demonstrates transparency and gives you control over the narrative.
4. Ensure access on survey day. Make the surveyor's job as easy as possible. Clear access to the loft hatch, move items away from walls in the cellar or basement, ensure all rooms are accessible, and make sure the surveyor can reach the consumer unit, boiler, and any other key areas. A surveyor who cannot access part of the property will note it as a limitation and may recommend further investigation.
5. Complete the TA6 form thoroughly and honestly. Many survey issues are also disclosure issues. If you have declared known problems on the TA6 and provided supporting documentation, there are no surprises when the survey report arrives — and the buyer is less likely to feel misled.

Sources and further reading

• RICS (Royal Institution of Chartered Surveyors) — Standards and guidance for residential property surveys, including the Home Survey Standard: rics.org
• PCA (Property Care Association) — UK trade body for damp-proofing, timber treatment, and invasive weed control specialists: property-care.org
• BRE (Building Research Establishment) — Research and guidance on building defects, including damp, structural movement, and timber decay: bregroup.com
• HSE (Health and Safety Executive) — Guidance on managing asbestos in domestic properties: hse.gov.uk
• HomeOwners Alliance — Independent advice for home buyers and sellers on survey results and common property defects: hoa.org.uk
• GOV.UK — Building regulations guidance for England, including Approved Documents for structure, fire safety, and moisture resistance: gov.uk
• NICEIC (National Inspection Council for Electrical Installation Contracting) — Register of approved electrical contractors and guidance on domestic electrical safety: niceic.com
• Institution of Structural Engineers (IStructE) — Guidance on subsidence, underpinning, and structural assessment of residential properties: istructe.org
• Environment Agency — Information on Japanese knotweed classification, treatment, and legal obligations: gov.uk/guidance/prevent-japanese-knotweed-from-spreading
• WaterSafe / Water UK — Information on drainage responsibilities and the transfer of private sewers to water companies: water.org.uk

Related guides

• Boiler Issues in Buyer's Survey: What to Expect

Frequently asked questions