hygroscopic salts in chimney breast

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farhi

New Member
Hi, hope someone can give me some advise.

A few years ago we had the attic all replastered after stripping down the wallpaper. We noticed a damp patch on the chimney breast and just assumed it was the plaster taking time to dry out. After painting it and that damp patch coming and going, i did lots of research and found it was hygroscopic salts, the damp patch tastes salty too, i licked the wall hee hee ;)
Anyway, im sick of having the dehumidifier on all the time so sanded down the paint, right back to the plaster and sprayed some Salt Neutraliser on the chimney breast. The damp patch is still there!!!!! I was hoping to save money this way. Ive sprayed it several times now:cry::endesacuerdo:
Please help. Its only the top corner of the attic chimney breast but that damp patch shows through on magnolia painted walls.
Help :(
 
algeeman

algeeman

It’s A Boy
Sometimes when ive plastered a big room i scrape the floor around the edges first then run the scraper through the middle so I think ive only got too 2 small rooms to clean.
The morale of the story is
"Its boring and who cares"
 
B

brimplas1

Well-Known Member
Chimneys should always be vented. It could be cold bridging from there being a clump of sh*te in the flue....
 
A.plasterer

A.plasterer

Private Member
farhi said:
Hi, hope someone can give me some advise.

A few years ago we had the attic all replastered after stripping down the wallpaper. We noticed a damp patch on the chimney breast and just assumed it was the plaster taking time to dry out. After painting it and that damp patch coming and going, i did lots of research and found it was hygroscopic salts, the damp patch tastes salty too, i licked the wall hee hee ;)
Anyway, im sick of having the dehumidifier on all the time so sanded down the paint, right back to the plaster and sprayed some Salt Neutraliser on the chimney breast. The damp patch is still there!!!!! I was hoping to save money this way. Ive sprayed it several times now:cry::endesacuerdo:
Please help. Its only the top corner of the attic chimney breast but that damp patch shows through on magnolia painted walls.
Help :(
Click to expand...
Hmmmm :estudioso: is it just wall licking ? Or is it Windows too? We have a trained team of counsellors :sisi:
 
F

farhi

New Member
This is a pic of the chimney breast. The paint has been sanded. Ive gone down to the plaster and have then used salt neutraliser spray. There is a darker patch between the slanted ceiling and chimney, thats where it is really salty.
 

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F

farhi

New Member
A close up of the chimney breast. Hope you can see the darker patch along the slant.
The vent is also not on the chimney breast itself. Its always been in that corner beside the breast itself
 

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Fatarm

Fatarm

Trainee mod
Possibly be soot contamination?..hack off effected area +300 mm beyond and fix on membrane and replaster.
or you could be buying salt neutraliser for ever.(y)
 
F

farhi

New Member
Fatarm said:
Possibly be soot contamination?..hack off effected area +300 mm beyond and fix on membrane and replaster.
or you could be buying salt neutraliser for ever.(y)
Click to expand...

Is soot contamination the same as salt contamination? How much will the membrane be for that size? Would i need to hack off all the plaster on the chimney and membrane it?:)Or could i just hack off that piece ive sanded and put membrane on? I wonder if membrane come in smaller sizes?
 
puddove

puddove

Private Member
farhi said:
Is soot contamination the same as salt contamination? How much will the membrane be for that size? Would i need to hack off all the plaster on the chimney and membrane it?:)Or could i just hack off that piece ive sanded and put membrane on? I wonder if membrane come in smaller sizes?
Click to expand...


it tastes different -------- :inocente::lol: smokey
 
Jgreenplastering

Jgreenplastering

Private Member
farhi said:
its gypsum plaster
Click to expand...

Hack it off back to brick.
It shouldn't be on there, gypsum is like a sponge with water.
It absorbs everything.
Chimneys are prone to having build ups of salts and contaminants from when used as a fireplace.

You need to hack it all of.
Make sure there is no leak and then take it from there


Sent from my iPhone using Tapatalk
 
F

farhi

New Member
Jgreenplastering said:
Hack it off back to brick.
It shouldn't be on there, gypsum is like a sponge with water.
It absorbs everything.
Chimneys are prone to having build ups of salts and contaminants from when used as a fireplace.

You need to hack it all of.
Make sure there is no leak and then take it from there


Sent from my iPhone using Tapatalk
Click to expand...

Thank you for your help. Thats going to be a big job isnt it? :rayos: What plaster would be needed to redo it? Would i need to have one of those damp membrane thingies on the brick before the new plaster goes back on top? Do you have any idea, the cost of the chimney being replastered again?
 
F

farhi

New Member
Could anyone recommend a membrane to put on the brick before replastering please, something cheap and cheerful please :D
 
Jgreenplastering

Jgreenplastering

Private Member
If you want a cheap option use treated battens with some dpc behind them, then board and skim.
If you want to do it properly I'd fix the membrane to the wall after all plaster is removed. Then dot an dab an skim.
Neither is a big job really.
If you put where your from you should get a contact off the forum.

We use Sov Chem membranes but you can get them anywhere online. You only need the 3mm mesh one for above ground.
Cheaper than the thicker ones.


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F

farhi

New Member
Jgreenplastering said:
If you want a cheap option use treated battens with some dpc behind them, then board and skim.
If you want to do it properly I'd fix the membrane to the wall after all plaster is removed. Then dot an dab an skim.
Neither is a big job really.
If you put where your from you should get a contact off the forum.

We use Sov Chem membranes but you can get them anywhere online. You only need the 3mm mesh one for above ground.
Cheaper than the thicker ones.


Sent from my iPhone using Tapatalk
Click to expand...


Thank you :)
 
F

farhi

New Member
flynnyman said:
Forget membrane just sand and cement and vent the chimney
Click to expand...

So i need to hack off all the plaster on that chimney breast to the brick, then sand and cement it? Does cement dry a grey colour? And can i just paint as usual?
Sorry, im new at all this :)
 
theclemo

theclemo

Private Member
farhi said:
So i need to hack off all the plaster on that chimney breast to the brick, then sand and cement it? Does cement dry a grey colour? And can i just paint as usual?
Sorry, im new at all this :)
Click to expand...

U need to skim the sand and cement.
 
Jgreenplastering

Jgreenplastering

Private Member
farhi said:
So i need to hack off all the plaster on that chimney breast to the brick, then sand and cement it? Does cement dry a grey colour? And can i just paint as usual?
Sorry, im new at all this :)
Click to expand...

In they it's cheaper but you need to remove all the traces of gypsum or it could affect the new finish.
Not worth the hassle of scraping every last bit off!


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