The Cost of Fixing Common Survey Defects in the UK — 2026 Guide

A SurveyReady compilation of what the most frequently flagged house survey defects actually cost to put right, based on published 2026 UK trade pricing guides — with guidance on how costs vary by region.

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Key findings

A full house rewire is the single most expensive "routine" defect. At a UK average of £6,000–£6,500 for a three-bed home, outdated electrics flagged on a survey typically cost more than damp treatment, boiler replacement and minor roof repairs combined.

Subsidence remains the costliest outcome a survey can flag. Underpinning for a typical 3-bed semi averages around £13,500 (mass concrete method), with severe cases exceeding £50,000.

London and the South East cost 15–30% more. Multiple trade pricing guides report a consistent premium of 15–30% for London and the South East across rewiring, roofing and other labour-intensive work. The Midlands, North and Scotland sit at or below national averages.

Damp is the most common finding — and frequently underestimated. Treatment costs £800–£3,000, but replastering damaged walls at £30–£70 per m² often adds as much again.

All figures are compiled from published 2026 UK trade cost guides — see the full methodology and sources below. Journalists and bloggers are free to reuse this data with attribution and a link to this page.

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National cost ranges by defect (2026)

The table below shows typical UK cost ranges compiled from Checkatrade, MyJobQuote, MyBuilder and specialist sources. Regional figures are not separately surveyed prices — they are the national ranges adjusted by the regional bands that these guides themselves report (see Regional Variation below).

All figures exclude VAT unless stated and exclude post-work redecoration. Ranges reflect spreads across multiple guides; where a source published an average from real homeowner quotes, that average is noted.

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Regional variation

Published trade cost guides consistently report regional adjustment bands — these are not precise per-region prices, but planning guidance:

London & South East: Approximately +15% to +30% above national average. Multiple guides cite 15–25% for roofing and rewiring; some cite up to 30% for rewiring in central London. Use +20% as a central planning figure.

Midlands, Wales, North, Yorkshire: Broadly at or slightly below national average. The national figures above are most representative for these regions.

Scotland & rural areas: Generally at the lower end of national ranges, though very remote areas can rise again due to travel and access costs.

For a firm price, always obtain at least three quotes from qualified local tradespeople.

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What each defect costs — and why surveys flag them

Damp (the most common survey finding)

Damp is consistently reported by surveyors as the most frequently flagged issue in UK homebuyer surveys, spanning rising damp, penetrating damp through external walls, and condensation from poor ventilation. National pricing for 2026 puts a typical whole-house damp treatment at £800–£3,000, with chemical injection DPC around £70–£120 per linear metre. The cost most buyers miss is replastering: removing and replacing salt-contaminated plaster at £30–£70 per m² can add as much as the treatment itself.

Negotiation note: properties with untreated damp commonly see price reductions of several thousand pounds after survey, so documented damp evidence is one of the strongest renegotiation levers a buyer has. See our guide on how to negotiate house price after survey for more on using defect costs in negotiations.

Outdated electrics / full rewire

Dated consumer units, missing earthing and ageing wiring are routine findings in pre-1980s housing stock. A full rewire of a 3-bed semi costs £4,500–£8,000 in 2026, with the UK average around £6,000–£6,500. This includes the consumer unit, cabling and certification but excludes plastering and decorating. Pre-1960 properties typically cost 10–20% more due to older construction methods. London and the South East see premiums of 20–30% above these figures.

Boiler and heating system

Surveyors flag boilers past their 10–15 year service life. A replacement combi installed costs £1,800–£4,500 in 2026, with real platform quote data showing a median around £2,300. System boiler upgrades or relocation work adds £500–£1,500. London and the South East typically run 10–20% higher.

Roof defects

Slipped or missing tiles, deteriorating flashing and cracked chimneys are among the most common external findings — often invisible from the ground. Minor repairs (1–5 tiles on a 2-storey) typically cost £150–£400; chimney flashing runs £400–£800. A full roof replacement averages £8,000 nationally with a realistic range of £4,000–£19,000 depending on size, material and complexity (£120–£275 per m²). Scaffolding for a 3-bed adds £800–£1,500.

Japanese knotweed

Knotweed within 7 metres of a property is flagged in mortgage valuations and usually requires a professional management plan paid in full before completion. A herbicide-based plan for a smaller infestation costs £1,000–£5,000; full excavation runs £4,000–£20,000+. An insurance-backed management plan with guarantee typically costs around £2,000–£2,500.

Subsidence and structural movement

Cracking, uneven floors and sticking doors can indicate movement. Where underpinning is required, costs range from £6,000 to £25,000+ depending on extent, ground conditions and method, with a 3-bed semi averaging around £13,500 for mass concrete underpinning. Severe cases can exceed £50,000. Structural engineer reports add £300–£1,500. Insurance may cover subsidence from insured events (e.g. leaking drains) but often excludes gradual movement.

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Methodology

The cost figures in this study are compiled from published UK trade cost guides current for 2026, including Checkatrade, MyJobQuote, MyBuilder, and specialist contractor data — several of which derive their figures from real homeowner quotes submitted to their platforms. For each defect category we report a national cost range and, where a source published an average drawn from real quotes, that average.

National figures exclude VAT and post-work redecoration unless otherwise stated. Costs vary substantially with property age, construction type, severity, and access — the ranges shown are planning guides, not quotes.

Regional figures are derived by applying the regional adjustment bands that these cost guides themselves report — a London and South East premium of roughly 15–30%, with the Midlands, North, Scotland and rural areas typically at or below national averages. These regional figures are therefore illustrative planning estimates, not separately surveyed regional prices. For a firm price, always obtain multiple quotes from qualified local tradespeople.

Figures last reviewed: June 2026.

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Sources

• Checkatrade cost guides — damp proofing, roof repair, roof replacement, new boiler, Japanese knotweed
• MyJobQuote cost guides — damp proofing, rewiring, underpinning, knotweed (based on real platform quotes)
• MyBuilder price guides — rewire, knotweed, boiler replacement
• Heatable boiler cost data — median of 2,000 quotes, Jan–May 2026
• Homebuilding underpinning guide — quantity surveyor estimates
• Mainmark UK — subsidence and underpinning cost data
• Environet UK — Japanese knotweed treatment costs
• ONS Construction Output Price Indices — general construction inflation context

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Frequently asked questions

What are the most common defects found in a house survey?

Damp is the most frequently flagged issue in UK homebuyer surveys, followed by roof defects (slipped tiles, flashing, chimney problems), outdated electrics, ageing boilers and plumbing, defective guttering, and signs of structural movement. Higher-risk but less common findings include asbestos, Japanese knotweed and subsidence.

How much should I budget for survey defects when buying a house?

Based on the cost ranges in this guide, a realistic contingency for an older property is £3,000–£8,000 depending on condition and region. Few properties need every common repair, and your survey report is the basis for negotiating repair costs off the purchase price rather than absorbing them yourself.

Can I renegotiate the price after a bad survey?

Yes — survey findings are the standard basis for renegotiation. Matching your price reduction to documented repair costs is far more credible than a round-number reduction, and properties with untreated damp or structural findings routinely see reductions of several thousand pounds.

Why do the same repairs cost more in London?

Labour costs. Published trade guides consistently report a 15–30% premium for London and the South East, driven by higher skilled-trade day rates. Materials are broadly similar nationally; the regional gap is almost entirely labour.

Are these figures quotes?

No — they are compiled estimates from published 2026 UK trade cost guides. Always obtain at least three local quotes for any work flagged on a survey.

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Before your next viewing, use SurveyReady to document what you see room by room and generate a RAG-rated assessment report with cost estimates — so the figures above are in your hands before you make an offer, not after.

Related guides: How much does a house survey cost? · Should I get a homebuyer survey? · How to negotiate house price after survey · House viewing checklist UK