Penetrating Damp Treatment
Penetrating damp comes from water getting in through the outside of a building — cracked render, failed pointing, a leaking gutter or downpipe, a bridged cavity or defective sills. Unlike rising damp it can appear at any height, often as a localised damp patch that gets worse after heavy rain. The fix is to stop the water getting in, then treat the affected wall.
Quick answer
Penetrating Damp Treatment typically starts from £250 — priced per job after survey — depends on the source and external repairs needed. We confirm a fixed written price after a survey, before any work starts.
What penetrating damp involves
Because the water comes from outside, treating the inside wall alone never lasts — the patch simply returns with the next downpour. We trace the actual entry point, whether that's failed pointing, cracked render, a blocked or leaking gutter, or a cavity bridged by debris, and put the external defect right first, then deal with the internal damage.
Penetrating damp is often confused with rising damp, but the pattern gives it away: it appears at any height and tracks the weather rather than sitting in a neat tide mark near the floor. A damp survey pins down the source. Where water has been getting in for a while it can also lead to timber problems, so woodworm and timber treatment is sometimes needed alongside, and badly contaminated internal plaster may need damp-proof re-plastering before redecoration.
What's included in every penetrating damp job
- ✓External water-entry point traced and repaired
- ✓Render, pointing, sills and rainwater goods checked
- ✓Internal damage treated once the source is dealt with
- ✓Advice on preventing recurrence
Get a survey for penetrating damp
Book a Free SurveyWhatsApp +44 7415 016237Check if we cover your area →When you might need penetrating damp
The most common situations we're called out for — if yours isn't listed, send a couple of photos through the contact form and we'll tell you exactly how we'd handle it.
Damp patches after rain
Localised damp that appears or worsens following heavy or wind-driven rain.
Failed render or pointing
Cracked external render, perished mortar joints or defective sills letting water through the wall.
Leaking gutters or downpipes
Overflowing or leaking rainwater goods soaking a patch of wall from outside.
How It Works
- 1
Book a free damp survey
Tell us what you’re seeing — a tide mark, black mould, blown plaster or a survey that flagged damp. We arrange a visit, usually within a few days.
- 2
We diagnose the real cause
On site we identify whether it’s rising, penetrating or condensation damp (they’re treated completely differently) and give you a clear, honest explanation.
- 3
You get a fixed written quote
A clear, itemised price for the recommended work — no pressure, no vague estimates that move on the day, and no charge for the survey on standard jobs.
- 4
We treat it and guarantee it
The work is carried out to industry standards, the area is left clean and ready to redecorate, and the treatment is backed by a written workmanship guarantee.
Damp Proofing Price Guide
Indicative pricing — every job gets a fixed, written quote after a survey. No hidden extras.
Damp survey & report
diagnosis
Free
Free for straightforward jobs; a detailed independent survey report is available for mortgage or purchase cases.
DPC injection (per wall)
rising damp
from £350
Chemical damp-proof course injection to a single affected wall — priced by length and access.
Damp-proof re-plaster
per room
from £600
Salt-resistant re-plastering after treatment, so the wall can be redecorated cleanly.
Basement / cellar tanking
waterproofing
from £1500
Structural waterproofing (tanking or cavity membrane) — quoted per project after survey.
Often needed alongside penetrating damp
Damp problems rarely come alone — these related treatments are commonly part of the same job, for example damp surveys & reports, damp-proof re-plastering and woodworm & timber treatment.
Where we cover penetrating damp
We provide penetrating damp treatment right across England, Wales and Scotland as part of our regular damp proofing coverage, including busy counties such as Greater London, Greater Manchester, Kent, Devon, Staffordshire, West Midlands, Hampshire and Merseyside. Not sure if we reach you? Check the full areas we cover or just send your postcode with your enquiry.
Penetrating Damp — frequently asked questions
What causes penetrating damp?
Penetrating damp comes from water getting in from outside — a cracked render, failed pointing, a leaking gutter, a bridged cavity or a faulty damp-proof course. Unlike rising damp it can appear at any height, and the fix is about stopping the water getting in, not just treating the wall inside.
How do I know if I have rising damp or condensation?
They're often confused. Rising damp shows as a tide mark up to about a metre on ground-floor walls, sometimes with salt staining; condensation shows as black mould in corners, around windows and in poorly ventilated rooms. A survey confirms which it is — the treatment is completely different, so getting the diagnosis right first matters.
How quickly can you survey a property in your area?
We cover your area regularly and can usually arrange a survey within a few working days — sooner for urgent cases such as a sale falling through on a damp report.
How long does damp proofing last?
A correctly installed damp-proof course and salt-resistant re-plaster should last for decades, which is why the work is backed by a written guarantee. The key is treating the actual cause, not just covering the symptom — which is what the survey stage is for.
Damp is treated by cause, not by symptom: rising, penetrating and condensation damp look similar but need completely different treatments, which is why every job starts with a proper survey and diagnosis before any work is quoted.
Book a free survey for penetrating damp
Tell us about the damp and your postcode — we'll arrange a survey and a fixed written quote.