Straight answers · Damp in UK homes
Damp gone.
Cause and all.
You have a wet wall and three companies telling you three different things. Here you find out which kind of damp you are actually looking at. What is putting the water there. And which fixes deal with that cause instead of covering it up.
- What it actually is
- What fixes it
- What it should cost
Start with what you can see
8 in-depth guides, and counting
Rising damp, and the test almost nobody runs
What rising damp actually is, why the moisture meter used on almost every survey cannot confirm it, and the laboratory method the British Standard points to instead.
Read it →Penetrating damp, and the wall that was never built for your weather
Water coming in sideways is a building fault with a location, not something the wall has caught. The exposure zone your wall stands in, and what the regulations say it needs.
Read it →Damp meter readings, and why there is no acceptable number
The reading almost every damp quote in the country is built on is a wood measurement. What the meter is really telling you, and what would settle the question properly.
Read it →Mould on walls, and why it keeps coming back
Cleaning it off is the easy part and it is not the part that matters. What the official guidance says about removing mould, about bleach, and about who is to blame.
Read it →Condensation, and why a dry wall still grows mould
The number that decides whether mould grows is not the dew point. The humidity to aim at, and how to tell condensation from the two kinds of damp people pay to have treated.
Read it →Damp proofing costs, and the half of the quote nobody shows you
The per-metre rate people search for is the smallest line on the bill. What the published guides say, where they disagree, and what a damp quote quietly leaves out.
Read it →Damp surveys, and why the free one exists
A home survey is built to pass a damp question onward, not to answer it. What RICS actually promises, what the free survey is for, and when paying is the cheap option.
Read it →The damp proof course, and the two minutes that could save you thousands
Your damp proof course has a required height above the ground and you can check it yourself with a tape measure. How the whole system works, and what defeats it.
Read it →No survey to sell you.
Nearly everything written about damp in this country comes from someone who wants to come and do the work. Here you get the answers I would give you over the fence. What the wet patch actually is. What is putting the water there. And what I would do about it if it were my wall.
Nobody pays for the verdicts
No damp-proofing firm owns this site, and nothing here is a paid-for opinion. When a treatment is the wrong answer to your problem, the page says so. If a recommendation ever earns me anything, the page discloses it plainly, right where it sits.
Cause first, always
Every answer starts with the same question. Where is the water coming from? Treat the wall instead of the source and it is wet again by next winter. Only now you have paid for it twice.
No waffle
Short answers first, the why underneath. You leave every page knowing what to do next, not with ten tabs open.
The questions everyone asks
Watch when it changes rather than what it looks like. Condensation gets worse in cold still weather with the room in use. Penetrating damp gets worse during and after rain. All three leave the same dark patch, which is why photographs settle nothing.
Condensation, penetrating damp and rising damp. And a fourth possibility nobody lists: salt left in the plaster. It pulls moisture straight out of the air and reads damp with nothing leaking, rising or condensing.
No, and that is not a technicality. The number on a handheld meter is a wood moisture scale, and the manufacturers say so in their own documentation. There is no published acceptable figure for masonry because the scale was never describing masonry in the first place.
The honest answer is that the visible signs do not separate it from anything else. BS 6576 puts it plainly: surface measurements cannot alone give proof of rising damp. A tide mark and a high meter reading are equally consistent with salt in the plaster, which draws moisture from the air once humidity passes about 75%.
Because it is usually provided by the company that would quote for the treatment. That is a structural conflict rather than an accusation, and it exists because a RICS home survey is built to pass the question on: RICS says its surveyor does not open up the fabric and uses a damp meter.
Nobody agrees, which is the useful thing to know before you judge a quote. Published guides put chemical DPC injection at £60 to £90 a metre and at £70 to £120 a metre, and a whole-house average at £1,250 and at £1,500 to £4,000. Inner London runs 20 to 25% above those.
They deal with condensation and nothing else. Pulling the room humidity down genuinely helps, because what decides whether mould grows is the humidity at the wall surface rather than in the middle of the room. But a dehumidifier cannot do anything about water arriving through the wall.
See all questions, or got one that is not here? send it over and the useful ones get a proper page.