Stains in chimney breast

[Goldspoon]

We have two rooms with old, sealed up fireplaces (there are air grates). Brown staining on plasterboard keeps coming through even after many attempts to repaint.

Chimneys have terracotta pots that are sealed on top (but have slits on sides).

Recently went on a Hetas course (3 day). Lecturer said that problem is almost impossible to stop (said it is damp and tar that is in the brickwork).

Has anybody else had/solved this problem?

 

[cmother1]

You can try painting over it with several coats of neat PVA adhesive, covering an area at least 6" bigger than the stain. No promises, mind.

 

[noseall]

Has anybody else had/solved this problem?

Strip the plaster back to the brickwork, apply an sbr/cement slurry then sand/cement render and skim using appropriate admixture in the render.

Chimney flues built using bricks only, i.e. no clay liners, are particularly vulnerable to the exhaust gasses from 'dirty' fuels, i.e. oil, coal wood etc.

The masonry becomes saturated with tar and soot and in particular, hygroscopic salts, leading to brown staining and leaching.

 

[joe-90]

That's a good post from Nosey.

 

[cmother1]

A real Rolls -Royce solution.

 

[stuart45]

Thanks for a great post noseall. For the past 10 years I've been painting the bedroom brown to cover the stains, but now I can change to magnolia.