North London Damp Cost Guide
Every damp, mould, waterproofing and timber price we quote across this site, gathered into one reference — with the factors that move quotes and the questions that keep them honest.
How much does damp proofing cost in North London (2026)? Headline ranges: damp & timber surveys £280–£450 · chemical DPC injection with replastering £70–£120 per metre (typical wall £800–£1,500; terraced ground floor £800–£5,000) · condensation and ventilation remedies £300–£1,500 (PIV units £800–£1,500 installed) · professional mould removal £200–£600 per room, £600–£1,500 whole-property · penetrating damp repairs £150–£3,000 by defect · subfloor ventilation £150–£900 · basement tanking £40–£80/m², cavity drain systems £70–£140/m², full basement schemes £5,000–£30,000+ · sump pumps £1,500–£3,500 (£120–£250 annual service) · cellar conversion £1,000–£30,000 by grade · woodworm treatment £400–£1,200 · wet rot £150–£2,500 · dry rot £1,000–£10,000+ · landlord compliance inspections £300–£500. All indicative across Barnet, Enfield, Islington, Camden, Hampstead and all 15 areas we cover; written quotes follow surveys.
Diagnosis and surveys
The prices that control all the others: damp & timber survey £280–£450 (two to four hours on site, written report, costed recommendations — the specification in Damp Surveys Explained); pre-purchase survey £300–£500 (addressed to the buyer, negotiation-ready); BS 8102 basement design survey £250–£450 (system selection, inflow assessment, pump sizing); focused mould assessment £150–£300; landlord compliance inspection £300–£500 (HHSRS-aware reporting within Awaab's Law-benchmark timescales).
The economics bear repeating: misdiagnosis is the most expensive event in damp treatment — a wrong verdict buys a four-figure remedy that can't work — and the survey fee exists to prevent it. Treat free contractor 'surveys' as the sales visits they are.
Damp proofing: rising, penetrating, DPC and subfloor
Chemical DPC injection with salt-retardant replastering: £70–£120 per metre — a typical affected wall £800–£1,500, a whole terraced ground floor £800–£5,000 by extent. Replastering specification matters: the salt-retardant coat is integral to treatment, not an extra. Bridging corrections — lowering ground, cutting back render, re-forming junctions — commonly £100s, and cure a large share of 'rising damp' outright. Penetrating damp: £150–£3,000 by defect — gutter and downpipe repairs £80–£400, local repointing £150–£600, full elevations £1,000–£3,000, render and stucco £300–£3,000+, flashings £150–£800, chimney works £200–£900. Subfloor ventilation: £150–£900 — clearing airbricks £150–£400, new airbricks £80–£150 each, periscope vents £120–£200 each, full elevation upgrades £400–£900.
Mould, condensation and ventilation
Professional mould remediation: £200–£600 per room, £600–£1,500 whole-property — containment, HEPA removal, surface treatment (the process on the mould removal service). The cause fix that must accompany it: £300–£1,500 for ventilation-led remedies — humidity-controlled extractor fans £150–£400 per room installed, trickle vents £20–£50 per window, PIV units £800–£1,500 installed (£800–£1,300 loft-mounted houses, £900–£1,500 wall-mounted flats), running for pence weekly. Insulated plasterboard on cold solid walls prices per wall by area. The system logic behind these choices is the ventilation guide's subject.
Below ground: waterproofing and conversion
Governed by BS 8102 and by water load: tanking (Type A) £40–£80/m² for sound masonry and modest loads; cavity drain membranes (Type C) £70–£140/m² — the habitable-space standard on London Clay; full basement waterproofing schemes £5,000–£30,000+ by area, depth, drainage complexity and finish; sump pump systems £1,500–£3,500 installed with battery back-up, annual servicing £120–£250 (non-optional — the unserviced pump is the classic failure); cellar conversion by ambition: dry storage £1,000–£3,000, tanked utility £3,000–£8,000, habitable £8,000–£30,000+. Movers of quotes: excavation for drainage falls, party-wall process in terraces, inflow rates demanding duplex pumps, reinstatement standard. Design surveys first, always — the full argument in the basement guide.
Timber treatment — and how to read any quote
Woodworm treatment £400–£1,200 (active infestations; historic holes cost nothing because they need nothing); wet rot £150–£2,500 — moisture fix plus local timber replacement; dry rot £1,000–£3,000 localised, £3,000–£10,000+ established, driven by exposure margins and reinstatement; structural repairs (sistered joists, spliced ends) priced with treatment. Species and activity determine everything, hence surveys before sprays.
Reading quotes, everywhere on this list: insist on itemisation against a written diagnosis; check the replastering or reinstatement specification included; ask what the guarantee covers, for how long, backed by whom; prefer PCA-member firms with named qualifications; and get comparable scopes from two or three providers for anything over £1,000. Instant ranges for your own case: the damp cost calculator, basement estimator and timber estimator.
Related services, guides and tools
Damp Surveys
The service this guide supports — diagnosis-first, with independent qualified providers.
View the serviceDamp Proofing (all services)
The service this guide supports — diagnosis-first, with independent qualified providers.
View the serviceBasement Waterproofing
The service this guide supports — diagnosis-first, with independent qualified providers.
View the serviceDamp Proofing Cost Calculator
Free, instant and anonymous — a two-minute head start on your answer.
Use the toolBasement Waterproofing Cost Estimator
Free, instant and anonymous — a two-minute head start on your answer.
Use the toolReferences & further reading: Property Care Association (PCA) · BS 6576 · BS 8102 · TrustMark · Checkatrade/industry pricing surveys. This guide is general information for North London property owners, not professional advice for a specific building — a survey provides that.
North London Damp Cost Guide FAQs
Different diagnoses, different scopes, different specifications — and sometimes sales-led surveying. Comparable quotes require a shared written diagnosis; that's the survey's role. Itemisation exposes the rest: what's being treated, what replastering is included, what the guarantee covers.
They're indicative 2026 ranges for North London — property size, access, extent and specification move real quotes within (and occasionally beyond) them. Central and high-value streets trend to upper ends through access and spec rather than postcode premiums. Written quotations follow surveys.
Accurate diagnosis, then the smallest remedy that addresses the actual cause: cleared airbricks, a corrected ground level, a repaired gutter joint and a decent extractor fan collectively fix more London damp than any amount of injection. The expensive route is treating the wrong thing.
For a single obvious defect (the leaking gutter over the patch), sensible repair first is reasonable. For anything recurring, spreading, low-level with salts, timber-adjacent or pre-purchase — yes: £280–£450 against the four-figure cost of guessing wrong.
Ranges here are indicative totals; individual quotes state their own VAT and reinstatement positions — which is exactly what itemisation is for. Redecoration after drying is typically excluded and worth budgeting separately.
For simple defined repairs, sometimes. For anything diagnostic — rising damp, recurring mould, basements, timber — a fixed quote without investigation is guessing with your money; reputable firms scope from findings.
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