Plastering after damp course

Heltershelter

New Member
Hi I have plaster infected with salt crystals which are drawing moisture from damp soot in chimney breast at internal wall with neighbouring property. have been advised to cut out plaster, apply salt neutraliser and damp course then plaster with salt retardant plaster. The issue is that before this was discovered a roofer said to try drilling into the chimney to allow air...im now concermed these holes will allow moisture through so not sure what to do! Any help would be appreciated...thanks.
 
Hi I have plaster infected with salt crystals which are drawing moisture from damp soot in chimney breast at internal wall with neighbouring property. have been advised to cut out plaster, apply salt neutraliser and damp course then plaster with salt retardant plaster. The issue is that before this was discovered a roofer said to try drilling into the chimney to allow air...im now concermed these holes will allow moisture through so not sure what to do! Any help would be appreciated...thanks.
I take it the chimney is boarded over and capped off? You need air flow through there right from the bottom, an air vent at the bottom and mushroom cowl on top or if the stack is fully capped your roofer is right you drill upwards at a 45 degree angle and tap 22mm copper pipe into the stack, water won’t track back up a copper pipe at 45 degrees
 
Hi I have plaster infected with salt crystals which are drawing moisture from damp soot in chimney breast at internal wall with neighbouring property. have been advised to cut out plaster, apply salt neutraliser and damp course then plaster with salt retardant plaster. The issue is that before this was discovered a roofer said to try drilling into the chimney to allow air...im now concermed these holes will allow moisture through so not sure what to do! Any help would be appreciated...thanks.
Applying a “damp course” is a waste of time and money
 
I take it the chimney is boarded over and capped off? You need air flow through there right from the bottom, an air vent at the bottom and mushroom cowl on top or if the stack is fully capped your roofer is right you drill upwards at a 45 degree angle and tap 22mm copper pipe into the stack, water won’t track back up a copper pipe at 45 degrees

Thanks..they chimney is capped off with slate and has holes for airflow...the holes aren't drilled at an angle with pipe, just drilled about 20 to create vent. Was told i should be cementing them before attempting to damp proof
 
Applying a “damp course” is a waste of time and money
Ah why's that? Was told the issue is that moisture can migrate into the plaster due to the plaster being full of these salt crystals absorbing moisture from the air but a damp course and special plaster on top would stop this
 
Ah why's that? Was told the issue is that moisture can migrate into the plaster due to the plaster being full of these salt crystals absorbing moisture from the air but a damp course and special plaster on top would stop this
Whoever’s told you that has made it up, the salt comes from the bricks not the plaster. You’ve got water coming in from somewhere in the chimney stack, could be the holes that have been drilled if you’ve done that many they need pointing up, you 1 hole in each side of the stack at the 45degree angle and tap some 22mm copper in, or you can take the slate off the top and fit a cowl but in both instances you need to fit a vent at the bottom to allow some airflow.
With regards to the salt, once the stack is vented chop the plaster back clean down the bricks and stabilise them, render in sand and cement and skim, no special plasters needed and to be honest iv never even heard of a special plaster that won’t let salt through.
Someone is trying to rip you off, what do they mean by damp proof it? Inject chemicals?
 
Whoever’s told you that has made it up, the salt comes from the bricks not the plaster. You’ve got water coming in from somewhere in the chimney stack, could be the holes that have been drilled if you’ve done that many they need pointing up, you 1 hole in each side of the stack at the 45degree angle and tap some 22mm copper in, or you can take the slate off the top and fit a cowl but in both instances you need to fit a vent at the bottom to allow some airflow.
With regards to the salt, once the stack is vented chop the plaster back clean down the bricks and stabilise them, render in sand and cement and skim, no special plasters needed and to be honest iv never even heard of a special plaster that won’t let salt through.
Someone is trying to rip you off, what do they mean by damp proof it? Inject chemicals?
Thanks again for your response. Just to be clear I've included a picture of the holes drilled. We had a damp specialist do a report and he recommended cutting the plaster out and replacing with salt retardant plaster, bought some dryzone stuff but read that it was worth using salt neatralizer and putting damp proof mesh down first as back up. The holes were drilled after advice from a roofer who was fixing some tiles and rendering some bits on the chimney to try and make it water right. A slate cap was fitted and he mentioned it would have holes or a gap allowed for ventilation. Water doesn't seem to be coming in however the plaster is still showing high damp readings. I'm guessing I've caused another issue by drilling into the stack from the bedroom
 

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Thanks again for your response. Just to be clear I've included a picture of the holes drilled. We had a damp specialist do a report and he recommended cutting the plaster out and replacing with salt retardant plaster, bought some dryzone stuff but read that it was worth using salt neatralizer and putting damp proof mesh down first as back up. The holes were drilled after advice from a roofer who was fixing some tiles and rendering some bits on the chimney to try and make it water right. A slate cap was fitted and he mentioned it would have holes or a gap allowed for ventilation. Water doesn't seem to be coming in however the plaster is still showing high damp readings. I'm guessing I've caused another issue by drilling into the stack from the bedroom
Your confused you can’t cause damp by drilling into the chimney from inside the house, I’m talking about drilling into your chimney stack outside on the roof because whoever has capped it off has either left a gap on top which is allowing rain water back into the chimney or the flashing or some other problem is letting water into the chimney somewhere you don’t get salt from air inside the house it’s water running down from the top outside.
Injecting dryzone is a waste of time the water is coming down now up
 
Thanks. the water coming in should be stopped as we had some repairs done. It's just that I now need to repair the wall and planned to stick the damp proof mesh on as added piece of mind then use dryzone salt resisting plaster on top. I'm worries that those holes I drilled will allow existing moisture from the stack back into the plaster if that makes sense?
 
Thanks. the water coming in should be stopped as we had some repairs done. It's just that I now need to repair the wall and planned to stick the damp proof mesh on as added piece of mind then use dryzone salt resisting plaster on top. I'm worries that those holes I drilled will allow existing moisture from the stack back into the plaster if that makes sense?
No the holes will let the chimney breathe, imagine if you had a cup full of water and you screwed the lid on, it would never dry out, place the same cup of water on the window cill with no lid and it would soon dry out. This is what your trying to achieve with the air vent.
To be honest if your getting salt that’s sometimes an indicator it’s drying out anyway but yes it does need nutrilising
 
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