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Case Study · Rising Damp Treatment
Treating Rising Damp in a North West London Home
Damp tide marks creeping up the ground-floor walls, blown plaster and salt staining. Here is how we traced it to a failed damp proof course and fixed it properly, in a residential property in North West London (NW10).
Written by Sam Fitzgerald, Founder & Surveyor
North West London (NW10)
Residential house
Rising damp to ground-floor walls
Failed or absent damp proof course
Chemical DPC + damp-resistant replaster
Long-term written
The Problem
The ground-floor walls showed the classic signs of rising damp: damp staining and discolouration along the lower walls, moisture reaching roughly a metre up from the floor, plaster breaking down, and hygroscopic salts showing through the surface. There was clear moisture gathering along the wall and floor junction.
These are the tell-tale markers of a damp proof course that has failed, broken down or was never there to begin with, letting ground moisture climb up through the masonry by capillary action. Left alone, it only gets worse: plaster keeps deteriorating, salts spread, internal finishes are damaged and indoor air quality drops.
Our Damp Proofing Solution
After a full inspection, we used a two-stage damp proofing approach: stop the moisture rising, then deal with the salt-contaminated plaster it had left behind. Treating only one of those is the usual reason rising damp comes back.
1. New chemical damp proof course
We drilled a series of injection holes along the mortar joint and installed a high-performance damp proofing cream. It penetrates the masonry and forms a long-lasting moisture barrier that stops ground moisture rising any further through the wall.
2. Removal of contaminated plaster
All plaster affected by moisture and hygroscopic salts was removed to the appropriate height. This step is essential: salts left in the old plaster keep attracting moisture from the air even after a new DPC is in, so leaving them is what makes a stain return.
3. Specialist damp-resistant replastering
The walls were then replastered with a specialist damp-resistant render system that resists residual moisture in the wall, stops salts migrating to the new finish, and gives a durable, decorate-ready base while the wall dries out safely.
The Outcome
The works resolved the rising damp and restored the affected walls. The property now has a new damp proof course giving long-term protection, the salt-contaminated plaster gone, fresh damp-resistant replastering, and dry, stable wall surfaces ready for decoration. The damp proofing is backed by our written long-term guarantee, with an insurance-backed guarantee available as an option on request.
Why It Matters
Rising damp has to be treated at both ends to stay fixed. A new damp proof course stops the moisture rising, but if the salt-contaminated plaster is left in place it will keep pulling moisture from the air and the staining returns, which is why so many “treated” walls fail again. Doing both, the DPC and the specialist replaster, is what makes the fix permanent. It is the same diagnosis-led approach we bring to all of our damp proofing work.
Spotting the Signs of Rising Damp?
Rising damp has a recognisable pattern. If you see these, it is worth getting it checked:
A damp survey will confirm whether it is genuinely rising damp before any treatment is recommended.
Frequently Asked Questions
How much does rising damp treatment cost?
It depends on how many walls are affected and how much replastering is needed. As a rough guide, treating a single room is often around £1,000 to £2,500, with a whole-house damp proof course typically £3,000 to £6,000 or more. We give a fixed price after a survey rather than a guess over the phone.
How long does a damp proof course last?
A correctly installed chemical damp proof course is a permanent remedy under normal conditions. Our damp proofing is backed by a written long-term guarantee, with an insurance-backed guarantee available as an option on request.
Why does rising damp come back after treatment?
Usually because the salt-contaminated plaster was not removed. A new damp proof course stops moisture rising, but salts left in the old plaster keep drawing moisture from the air, so both the DPC and the replastering are needed for a lasting fix.
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Sam Fitzgerald is the founder of Advanced Damp and a working damp and structural waterproofing surveyor diagnosing and treating moisture problems in residential and commercial properties across London and the South East. He is FODCS certified (a Federation of Damp Certified Surveyor) and a member of the Federation of Damp. His hands-on work covers rising damp, penetrating damp, condensation, basement waterproofing to BS 8102, and thermal imaging surveys, and he has personally completed over 400 damp surveys across properties of every type and age. Everything he writes draws directly from jobs he has carried out. He does not write about treatments, products or causes he has not dealt with first-hand in the field.
