Penetrating damp treatment and damp proofing in London
Penetrating damp pushes sideways into a wall, and a particular defect is always to blame. It might be cracked render, a gutter spilling down the brickwork, pointing that has crumbled, or soil heaped above the damp-proof course. The cure is to locate that fault and repair it. Painting a waterproof layer on the inside and hoping it holds does not solve anything.
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What the job covers
- Finding and repairing where water gets in from outside
- Installing new damp-proof courses and repairing old ones
- Repointing, render repairs and fixing other defects
- Replastering inside with the right system once the cause is fixed
- Correcting ground levels and drainage next to a wall
- Gutter and downpipe faults that lead to penetrating damp
Things to check before booking
A few of these points could mean you need no visit at all. We would sooner you knew that.
Coat the inside without curing the cause and the damp simply moves
Waterproof paint or tanking on an inside wall hides the mark, yet water keeps coming in. Often it spreads sideways and appears in a fresh spot. Deal with the outside defect before anything else.
Faulty guttering tops the list of causes
When a leaking or blocked gutter sends water down an outside wall for months, the result looks just like what people call rising damp. Looking at the gutter above the damp patch is free and rules out the most frequent culprit.
The height of the ground matters more than you might think
Build a patio, path or flower bed up a wall past the damp-proof course and it bridges the course, so moisture from the soil passes straight into the bricks above. Sometimes lowering that ground is the real fix, with no work on the wall at all.
New plaster needs a dry wall and the correct system
Plaster a wall before it has dried out, or use standard plaster where a breathable or salt-retardant system is called for, and the damp comes back. We agree this within the job instead of leaving it to the decorator or tiler who follows.
Questions people ask us
What is the difference between penetrating damp and rising damp?
Penetrating damp enters sideways through one particular defect and may show at any height. Rising damp climbs from the ground up through the wall, and only as far as groundwater can wick, which is normally less than a metre.
Once the cause is fixed, will the mark on my wall disappear?
Give the wall time to dry. That can take weeks, depending on how thick it is and how long it stayed wet. Decorate too early and the moisture still inside gets trapped under the new finish.
Can you fit a damp-proof course?
Yes. We install new ones and repair existing ones that have failed or been bridged.
Is it safe to leave it, or will it get worse?
Penetrating damp usually worsens if ignored. Timber can suffer and the wet area of wall spreads. Once it has been identified, fixing it is better than keeping an eye on it.
When the cause is plumbing
If a leaking pipe or fitting is behind the problem, not damp as such, these pages explain that work.
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General Plumbing
Radiators, pipework, taps and toilets: the small jobs that keep getting put off.
Read about General Plumbing -
Leak Detection
Acoustic and thermal equipment to trace hidden leaks before any floor is lifted.
Read about Leak Detection
Other damp and condensation pages
Further reading
Looking for penetrating damp & damp proofing in London?
Let us know the problem and your address, and you will hear the cost before any work begins.