I have a 1930 semi, in the lounge we have damp on the chimney breast. The top is capped with a vented cowl. Is the damp coming from the floor? The fire place is not used and has a fake log burner installed. This is an internal wall with the neighbour. I’ve attached an image it is like this on the other side. View attachment 379069
Damp on chimney brest
- Thread starter essex123456
- Start date
Not sure as rest is ok.
Poster# 2 and #4,
Why would "lime plaster" have been used instead of gypsum - as far as we can see thats not a remedial repair?
Using the term "lime plaster" is also wrong in this context - a mix of "lime render" at 3:1 sand and NH lime is the correct remedial render mix.
Why would "lime plaster" have been used instead of gypsum - as far as we can see thats not a remedial repair?
Using the term "lime plaster" is also wrong in this context - a mix of "lime render" at 3:1 sand and NH lime is the correct remedial render mix.
Last edited:
OP,
Why not post pics of the whole chimney breast?
Does the neighbour have damp issues on the party wall?
Is the floor solid or suspended?
Have you ever had the flue swept?
Why not post pics of the whole chimney breast?
Does the neighbour have damp issues on the party wall?
Is the floor solid or suspended?
Have you ever had the flue swept?
I’ll do some pics of it, floor is solid, neighbour doesn’t have issue. Not had chimney swept as it’s not used. I knocked the breakout out a few years back. Was hoping to sort this summer.
OP,
Still waiting for pics?
Still waiting for pics?
Just taken these
OP,
Thank you for the pics. Pics of the return wall on the left side of the chimney breast might also have helped?
You need to sweep the chimney flue regardless - people in the 1930's & 1940's & 1950's used solid fuel.
What is the "breakout"?
Does your neighbour have these damp issues?
Its possible that the cause of your rising damp is a soil filled fender wall below where the original concrete hearth was. If you have a suspended floor with an adequate crawl space then any existing fender wall could be examined from below?
Because of the height of the damaged plaster on the LH chimney breast cheek there might also be Hygroscopic chemicals penetrating through the chimney breast brickwork
Why not remove the skirtings on either side of the chimney breast, & hack off to 300mm above & beyond any signs of affected gypsum plaster plus hack sawing off any rusted metal angle bead - replace with a length of plastic angle bead.
You could then hopefully make good with a lime render.
Thank you for the pics. Pics of the return wall on the left side of the chimney breast might also have helped?
You need to sweep the chimney flue regardless - people in the 1930's & 1940's & 1950's used solid fuel.
What is the "breakout"?
Does your neighbour have these damp issues?
Its possible that the cause of your rising damp is a soil filled fender wall below where the original concrete hearth was. If you have a suspended floor with an adequate crawl space then any existing fender wall could be examined from below?
Because of the height of the damaged plaster on the LH chimney breast cheek there might also be Hygroscopic chemicals penetrating through the chimney breast brickwork
Why not remove the skirtings on either side of the chimney breast, & hack off to 300mm above & beyond any signs of affected gypsum plaster plus hack sawing off any rusted metal angle bead - replace with a length of plastic angle bead.
You could then hopefully make good with a lime render.
The floor is solid, so no crawl space. I’m going to do the room up this summer so will take some plaster etc off to see.
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It's a fire place. It's 1930's so most likely has had loads of coal fires there over its lifetime. Combustion gases and water down the chimney when the chimney was used, make acids (like acid rain). The acids react with lime based building products and create salt compounds within the bricks and mortar - concentrated around the hearth itself. (just like acid rain and pollution erodes limestone buildings) These salts are hygroscopic and will pull water from the room air and grow crystals.
All the "damp" is most likely coming from the room air (just as it does in our house with the same situation). I have solved this by taking the plaster off, isolating the bricks from the room air first with an SBR slurry and then by overboarding and using foam adhesive (important because water based adhesives will still leach the salts to the surface). Room air can't get to the salts, problem goes away. This isn't theory, it is what I have done in my own house to 100% solve this problem.
All the "damp" is most likely coming from the room air (just as it does in our house with the same situation). I have solved this by taking the plaster off, isolating the bricks from the room air first with an SBR slurry and then by overboarding and using foam adhesive (important because water based adhesives will still leach the salts to the surface). Room air can't get to the salts, problem goes away. This isn't theory, it is what I have done in my own house to 100% solve this problem.
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