Damp in centre of chimney wall

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Clivek

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Having just had the walls re plastered in our 400 year old cottage, the side of the chimney just will not dry. It has dried all around the edge, but in the centre it still looks damp and white salts are starting to come through. The fireplace has a log burner in it which is regularly used. The plasterer who did the job says he has never seen this before and can't offer any help. Any help would be great as we must start decorating soon.
 
Soot contamination.
This soot and smoke contains the salts, minerals, tars and other chemicals that affect so many chimney breasts making them look and feel damp. Salt is very absorbant 'hygroscopic' so it pulls moisture damp into the plasterwork from the surrounding warm air (warm air holds more moisture than cool air). .......




C&p king:RpS_biggrin:
 
Clivek said:
Having just had the walls re plastered in our 400 year old cottage, the side of the chimney just will not dry. It has dried all around the edge, but in the centre it still looks damp and white salts are starting to come through. The fireplace has a log burner in it which is regularly used. The plasterer who did the job says he has never seen this before and can't offer any help. Any help would be great as we must start decorating soon.
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Was it originally done in a lime plaster I guess so by age of building? has it been re-done with lime?? This allows the chimney to breath it can also react with gypsum products if your plasterer has re-plastered in bonding perhaps
 
Fatarm said:
Soot contamination.
This soot and smoke contains the salts, minerals, tars and other chemicals that affect so many chimney breasts making them look and feel damp. Salt is very absorbant 'hygroscopic' so it pulls moisture damp into the plasterwork from the surrounding warm air (warm air holds more moisture than cool air). .......




C&p king:RpS_biggrin:
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Could this form like a clear sticky liquid on the the walls? Ive just looked at a job where the walls in the fireplace had a clear liquid on them and it was making the paint flake off ?



I'm using A Plasterers forum app and so should You !
 
thebigfella said:
Could this form like a clear sticky liquid on the the walls? Ive just looked at a job where the walls in the fireplace had a clear liquid on them and it was making the paint flake off ?



I'm using A Plasterers forum app and so should You !
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Cant say ive seen that bigfella..:RpS_unsure:
 
Me neither it's weird because where there is bare plaster from where the wallpaper was its got this liquid on it but the plaster doesn't look damp and dark just the normal colour ?


I'm using A Plasterers forum app and so should You !
 
Hey thebigfella

thebigfella said:
Me neither it's weird because where there is bare plaster from where the wallpaper was its got this liquid on it but the plaster doesn't look damp and dark just the normal colour ?

This is normally caused by the hygroscopic salts continually wetting the wall paper paste, salts are a pain in the bum around around the chimney area.


I'm using A Plasterers forum app and so should You !
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Has there been a back boiler in the chimney mate and its' got a slow leak in it? I took one out last weeek for someone and did'nt realise how big they are. I just quoted to pull it out but in the end I had to take nearlt the whole fireplae down as the pipes branched outward behind the bricks which must have been bricked over after the bolier was put there.
 
Thanks for all your replies. We do not live in a bungalow nor has their been a back boiler in the past. I think "Fatarm" got it right in that it's soot contamination. My question is what do I do about it before I decorate the wall?
 
Clivek said:
Thanks for all your replies. We do not live in a bungalow nor has their been a back boiler in the past. I think "Fatarm" got it right in that it's soot contamination. My question is what do I do about it before I decorate the wall?
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Cheapest option.....is to hack off the damp looking plaster 300mm beyond damp area and, apply salt neutraliser then waterproof render the patch and then re-skim the entire chimney breast.....if you just decorate its gonna keep comin back....
 
Hey Clivek

Could you be more specific in what type of plastering you had done please? Was it lime, sand and cement, or a gypsum over the top?
 
if it's an old building that doesn't have a modern flue/lining occasional use of the fire doesn't keep the lime render on the inside of the chimney dry, warmth draws moist cold air in and stays there, the render on the inside of chimney would have failed in places aswell, builds up and causes moisture.
 
Do you find that the lime render on the inside of the chimney then is wet if a fire is not often used
 
Sh*t didn't see your last post.

Well if I was you first thing I would do is cap any redundant flues as that is the number 1 problem I find next to flashings when it comes to chimney dampness.
Make sure you put a vent in where the fire place was as you need a circulation of air similar to a suspended floor in order to keep it dry.
I am doing a bit of work at the moment the whole house has a catalogue of defects from zero maintenance and also work done by cowboys.
When ever your looking at defects you need to just eliminate things as you go, sometimes it can be frustrating.
 
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