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Damp Proofing

Damp patches on first floor bedroom on old double flue chimney

Anonymous user 09/03/2024 - 3.19 PM

Hi there. I had water ingress through the roof adjacent to the external chimney of a 1950's brick-built house, which showed up on the ceiling and outside wall of the upstairs bedroom on and above the site of the chimney. It had a double flue, with one for an upstairs fireplace which had been removed, and one which was in use for the downstairs fireplace, which had had a gas fire installed maybe 20 years ago. I removed that downstairs fireplace and its gas fire, since I turned the room into a kitchen and sited the cooker & hob where the old fireplace had been. I installed an extractor fan above the hob, venting into the old chimney. The roofer replaced old lead flashing round the chimney with new lead flashing, took off old cracked chimney pot for the downstairs flue and replaced it with an "elephant's foot" pot, and replaced the concrete slab which blocked the old, upstairs removed fireplace chimney and held the new chimney pot. This seemed to stop the water leak, and after some weeks, the wall appeared to be drying out nicely. So I redecorated, using a good stain blocker on the old water stains. However, after about 8 months, damp patches started to reappear on the outside wall of the upstairs bedroom, and are getting worse. A meter show high damp readings on these patches, but there is no visible water. There are perhaps 10 separate damp patches over about one square metre of wall, the smallest being maybe 5 cm in diameter, the largest being maybe 30 cm in diameter. They are an orangey-yellow in colour, deeper shade at their centres, fading to just wet-looking at the edges The site of the damp is NOT on the flue of the old, removed fireplace in the room, but on the adjacent flue which served the downstairs fireplace of the kitchen, now in use for the extractor fan (which I very seldom use). I would so appreciate any advice please.

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4 Answers

Buildfix Property Services Ltd

Rating: 5 out of 5

Stafford

The year your house was built is borderline as to whether the walls were plastered with lime or Gypsum plaster. Forget the battery operated pin damp meter, they only identify the electrical resistance of the minerals in moisture on the wall, basically they were invented for measuring the moisture content of wood and contrary to a whole industry using them for identifying damp, they don't tell you if the building material is wet or not, basically they don't work. The only way to find the true cause of surface or penetrating damp is to measure the real moisture content of the building. Your problem is probably Hygroscopic Salts and atmospheric conditions but you need a true damp survey looking at and measuring data from a number sources to find the cause. At Buildfix we spend 7 days recording atmospheric conditions in your property and then take samples of your effected building material and measure it's true moisture content. It's the only way to find the real cause and understand what is needed to resolve the problem, we can save you thousands in unnecessary, injection Damp course's and plaster being knocked of walls.

Answered26 January 2021

Damp Cure Services

Rating: 5 out of 5

Cambridge

The only response worth reading is from buildfix as that advice is spot on. 👏👏👏

Answered20 February 2021

Property presentation services

Rating: 4.7 out of 5

Hull

If the problem is on the first floor . The problem will be most probably from penetrating damp or condensation, a breakdown of the damp course would not cause this !

Answered28 January 2021

East Coast Construction

Rating: 4.9 out of 5

Cramlington

Best to get a pca registered surveyor out for an independent report

Answered6 February 2021