Advice - damp on an internal wall

cornsack

Member
Hi all,

Just been to look at a job. It's in a shop /salon along a terraced road and they have some issues with damp, but mainly just on one wall. I wouldn't claim to be an 'expert' on damp so hoping for some backup/advice on the best remedy.

The wall in question is a shared wall, backing on to the shop next door. If it was an external wall it would make a bit more sense to me. But it's not so my only inclination is that it could simply be caused by the the thickness/couple of layers of basecoat I noticed (see photo).

What's generally a good fail-safe option to go for if not 100% on the damp cause? My thinking is to hack off all the plaster for sure and then maybe coat brickwork with watered down SBR and float and set using hardwall/renovating plaster. Or just dot and dab the wall, would that be a safe option? Again, not an external wall and owner said next door don't have the same problem. Would rather avoid sand and cement if possible because of the logistics of mixing up in a shop with no parking and also the need to make the job as quick as possible for the shop owner not to lose too much business.

The building is victorian and the background is brickwork.

Any advice muchly appreciated.
 

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smarts

Active Member
Damp can still rise if it's on an internal Brock wall you could take of skirting and find the lowest mortar joint u can find and inject it every 100mm
 

Dacha

Member
Do you plan to hack off whole wall or just a section ?
you never know with a damp. it has capillary movements.
all you mentioned seem alright.
If you are doing just a patch, that much sand and cement you can mix up by hand.
 

JessThePlasterer

Queen Jess Elizabeth I
I am no damp expert so others may contradict me but I would not be dot and dabbing. I’d remove the skirt and hack off a good way above that. Personally I love limelite in Victorian houses as it breathes. And you can just mix in a bucket. If you patch s/c just to the affected area the water will still want to go somewhere
 

cornsack

Member
Thanks for the quick replies everyone. I like your idea @JessThePlasterer. Have been interested in the stuff before but never taken the plunge. What's the top coat (finishing plaster) like to use? You experienced it much? Or is it safe enough to use multi-finish over the limelite base coat?
 

carys

Well-Known Member
Hi all,

Just been to look at a job. It's in a shop /salon along a terraced road and they have some issues with damp, but mainly just on one wall. I wouldn't claim to be an 'expert' on damp so hoping for some backup/advice on the best remedy.

The wall in question is a shared wall, backing on to the shop next door. If it was an external wall it would make a bit more sense to me. But it's not so my only inclination is that it could simply be caused by the the thickness/couple of layers of basecoat I noticed (see photo).

What's generally a good fail-safe option to go for if not 100% on the damp cause? My thinking is to hack off all the plaster for sure and then maybe coat brickwork with watered down SBR and float and set using hardwall/renovating plaster. Or just dot and dab the wall, would that be a safe option? Again, not an external wall and owner said next door don't have the same problem. Would rather avoid sand and cement if possible because of the logistics of mixing up in a shop with no parking and also the need to make the job as quick as possible for the shop owner not to lose too much business.

The building is victorian and the background is brickwork.

Any advice muchly appreciated.
First have u checked next door ask them if they had problems if so have they sorted it out if not option 1 hack meter up inject wall use proper waterproofer salt neutraliser if your using boards fix whith instant stick other option hack meter up Harle wall whith p gravel hydrolic lime for key scratch float wall up whith sharp sand building sand hydrolic lime and finish off whith lime finish plaster skim the wall will breath then
 

cornsack

Member
@smarts what product do you use for injecting? Can you plaster over it same day/next day? I've been in after injection course but never been there to watch someone do it
 

carys

Well-Known Member
@smarts what product do you use for injecting? Can you plaster over it same day/next day? I've been in after injection course but never been there to watch someone do it
I'd get the lads that inject in to the jobthat what they do and they be no comeback on you then if the damp comes back
 

JessThePlasterer

Queen Jess Elizabeth I
Thanks for the quick replies everyone. I like your idea @JessThePlasterer. Have been interested in the stuff before but never taken the plunge. What's the top coat (finishing plaster) like to use? You experienced it much? Or is it safe enough to use multi-finish over the limelite base coat?
I’m going to get slated for this but I’ve gone over it with multi or board with no problems. I have rang customers after a good while to make sure it was all good. However you should of course use the limelite finishing plaster over the top, it hangs for a bit but can go quite suddenly. You can do a search here for discussions on it. Just make sure you don’t use pva on the limelite before finishing plaster, pva will hang on the limelite for ten thousand years!
 

carys

Well-Known Member
I’m going to get slated for this but I’ve gone over it with multi or board with no problems. I have rang customers after a good while to make sure it was all good. However you should of course use the limelite finishing plaster over the top, it hangs for a bit but can go quite suddenly. You can do a search here for discussions on it. Just make sure you don’t use pva on the limelite before finishing plaster, pva will hang on the limelite for ten thousand years!
Waste of time and money if you use pva or pink on wall whith lime you start whith hydrolic you finish whith hydrolic for it to work got to start from scratch and I think the only time lime render works best on stone work by the way it waste of time injection stone wall seen many people do it waste of money and time
 

JessThePlasterer

Queen Jess Elizabeth I
Waste of time and money if you use pva or pink on wall whith lime you start whith hydrolic you finish whith hydrolic for it to work got to start from scratch and I think the only time lime render works best on stone work by the way it waste of time injection stone wall seen many people do it waste of money and time
Limelite isn’t really a lime render though. To be honest I don’t know much about injecting walls at all. Like I said I’m certainly no damp expert. I think it can be one of the most confusing things, so many causes and so many solutions on offer.
 

carys

Well-Known Member
Limelite isn’t really a lime render though. To be honest I don’t know much about injecting walls at all. Like I said I’m certainly no damp expert. I think it can be one of the most confusing things, so many causes and so many solutions on offer.
You can get hydrolic limelight yes very confusing damp issues no damp expert my self been at it 27 years seen so many damp houses in North Waleslol so I think life experience is better sometimes than going to collage
 

BobbyJack

Well-Known Member
I only use membrane for damp issues. All it takes is a mis understanding of a plaster product or not done correctly and there is a possibility the damp will still come through. Nothing is coming through plastic.
 

Dropsalot

Private Member
Damp is moisture. Moisture evaporates in the right conditions. Your job is to find the source of the moisture and stop it. Stop the,source of the damp.
Then get all the salt infected plaster off and let the rest of the trapped moisture evaporate. After that, apply a good backing coat like limelite or Bauer.
If you absolutely have to inject the walls, use dry zone. It’s easy to use.
 

cornsack

Member
You can get hydrolic limelight yes very confusing damp issues no damp expert my self been at it 27 years seen so many damp houses in North Waleslol so I think life experience is better sometimes than going to collage

To be fair, @JessThePlasterer was basing everything she said on experience. Which like you said, is best.
 

cornsack

Member
Thanks for all the help everyone. Much appreciated. @RobJack how does one fix a plastic sheet to the wall and then plaster over it? Basic stuff I'm sure, I've just never done it
 

BobbyJack

Well-Known Member
Thanks for all the help everyone. Much appreciated. @RobJack how does one fix a plastic sheet to the wall and then plaster over it? Basic stuff I'm sure, I've just never done it

It's fixed with plastic plugs mate. Put the membrane on the wall. Drill the plastic and wall. Hammer plastic plugs into the wall. It's quite easy but better with two price. One to hold plastic membrane in place initially and remove any slack so it's tight to the wall.
 

cornsack

Member
It's fixed with plastic plugs mate. Put the membrane on the wall. Drill the plastic and wall. Hammer plastic plugs into the wall. It's quite easy but better with two price. One to hold plastic membrane in place initially and remove any slack so it's tight to the wall.

Okay thanks. And you can plaster over it with any backing plaster (limelite, Bauer, s&c, etc.) ? Sorry for the amateur hour. Plastic being so waterproof seems like there would be no suction and nothing for the plaster to bond to. I'm probably missing something obvious.

You recommend any particular membrane/plugs?
 

BobbyJack

Well-Known Member
Okay thanks. And you can plaster over it with any backing plaster (limelite, Bauer, s&c, etc.) ? Sorry for the amateur hour. Plastic being so waterproof seems like there would be no suction and nothing for the plaster to bond to. I'm probably missing something obvious.

You recommend any particular membrane/plugs?

No worries mate. You can buy 2 types. One with mesh and one without. The one without gets pinned to wall then stud frame in front and board as usual. For the one with mesh you dab boards onto it directly. Ideally the adhesive shouldn't touch the plastic plugs. If it's going to fail anywhere the plug that goes through the plastic would be the probable place so if adhesive is on the plug moisture could travel through it. I think the chance of this happening if installed correctly is nil but best practise and all that.
 
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