Plaster after damp proof treatment?

[Welderpaul]

This property has had damp treatment many years ago, but never replastered. It looks dry.

Solid walls, 1890's terrace. I get that using hardwall and multi finish is not the right thing to do if there is some damp remaining, or likely to wick through.

So, i was looking at using Limelite renovating plaster and Limelite high impact to give a breathable finish.

The alternative would be Thistle Dricoat and Thistle Board Finish

Does anyone have any experience or forum words of wisdom they can offer?

 

[JOEPRO]

Is that an external wall? Aka the wall is exposed to outside. Or is it a party wall?

Is it a solid or cavity wall?

 

[addjunkie]

If you go breathable, youll need breathable paint too.

 

[brightspark]

any damp just tank it with tanking slurry with added sbr bonding agent and drill and inject injection jelly . undercoat with hardwall then multifinish . hardwall is salt free and recomended by sovereign ive just done some in my house. ive just tanked someones garage water was p.issing up from cracks in the floor and through the walls all sorted and dry now .dug land drains round the garage and summerhouse as well

 

[Welderpaul]

Is that an external wall? Aka the wall is exposed to outside. Or is it a party wall?

Is it a solid or cavity wall?

Party wall, solid

 

[Colin Barron]

This property has had damp treatment many years ago, but never replastered. It looks dry.

Solid walls, 1890's terrace. I get that using hardwall and multi finish is not the right thing to do if there is some damp remaining, or likely to wick through.

So, i was looking at using Limelite renovating plaster and Limelite high impact to give a breathable finish.

The alternative would be Thistle Dricoat and Thistle Board Finish

Does anyone have any experience or forum words of wisdom they can offer?


View attachment 456996

Ring the Sovereign Chemicals rep for your area. If you don't have a good dampness tester he will have one.
Basically from memory, Sovereign will give you a process sheet, you repair any damage to the wall. then paint anti sulphate (bostik) onto the wall, then paint an sbr solution on it, then paint on a slurry of sbr, double washed sand and low sulphate cement. When this is almost dry another layer of sbr, double washed sand and low sulphate cement. When this is dry you can plaster and finish level with the other surface. If the plaster above is not so good it may be best to dry line which is basically glueing plasterboard to the wall. First check is whether the damp coarse is satisfactory. Don't bodge or you will need to revisit the problem.

 

[JOEPRO]

Party wall, solid

OK so being a party wall it won't really breathe as such like an external wall will. For example your neighbour likely does not have fully breathable lime finish and paint.

So in your case if it were my house I would dot and dab on foil backed plasterboard. That will maintain a good finish even if the wall does build up small amounts of damp over time.

Insulation doesn't add anything since it's a party wall both houses cancel each other out.

 

[Welderpaul]

OK so being a party wall it won't really breathe as such like an external wall will. For example your neighbour likely does not have fully breathable lime finish and paint.

So in your case if it were my house I would dot and dab on foil backed plasterboard. That will maintain a good finish even if the wall does build up small amounts of damp over time.

Insulation doesn't add anything since it's a party wall both houses cancel each other out.

Fair shout with it being a party wall. Not enough thickness to get a board and dab, and i don't want to build out the full walls.

 

[JOEPRO]

Fair shout with it being a party wall. Not enough thickness to get a board and dab, and i don't want to build out the full walls.

The original plaster looks to be about an inch thick - does it have cement in it by any chance?

You can get 12.5mm foil backed plasterboard and dab it plumb and tight to the walls. It won't be any different space wise to your original plaster if you chip the rest of it off in that area to ceiling. I'd do the fireplace also and stop the board 12 inches from the opening and use cement there to fill in edges. Fire surround would cover the gap.

The only real alternative is to fill back in what has been taken off with specialist damp proofing sulphate resistant cement then plaster. Should be OK but foil back board will stand a better chance IMO.

 

[Colin Barron]

OK so being a party wall it won't really breathe as such like an external wall will. For example your neighbour likely does not have fully breathable lime finish and paint.

So in your case if it were my house I would dot and dab on foil backed plasterboard. That will maintain a good finish even if the wall does build up small amounts of damp over time.

Insulation doesn't add anything since it's a party wall both houses cancel each other out.

There was probably a damp problem because the plaster has been hacked off. The bricks under the damp coarse are still wet so unless the wall is tanked and floor for about 300mm the damp will return and all the work/ skirting boards/ flooring and decoration will have been a waste of time. If you must use this method allow a small gap between the floor and the board.

 

[JOEPRO]

There was probably a damp problem because the plaster has been hacked off. The bricks under the damp coarse are still wet so unless the wall is tanked and floor for about 300mm the damp will return and all the work/ skirting boards/ flooring and decoration will have been a waste of time. If you must use this method allow a small gap between the floor and the board.

Op's post number one said it was already damp treated years ago and the wall is dry.

Need more information from OP really. What treatment method was used and why has the plaster been hacked off now if the wall was otherwise sound and dry?

 

[Colin Barron]

Op's post number one said it was already damp treated years ago and the wall is dry.

Need more information from OP really. What treatment method was used and why has the plaster been hacked off now if the wall was otherwise sound and dry?

The two courses of bricks below the damp proof course will still be wet.

 

[JOEPRO]

The two courses of bricks below the damp proof course will still be wet.

If the walls had a damp proof course that is. They may have had none.

The treatment was most likely silicone injection DPC which is a very basic and not great treatment. It only really has a chance of working in a brick wall. And yes that silicone injection line will be dry above and damp below.

Electro osmosis is the other type of treatment which uses a small electric charge to drive the damp downwards. That type tends to be more effective and is preffered over silicone injection by historic environment inspectors. This type would be drier lower bricks.

Really the foil plasterboard will be fine and stop it say 15mm from the floor boards and add foil tape over the edges before offering up. Then leave a small gap below new fully primed skirting boards too depending on the floor finish.

 

[Colin Barron]

This property has had damp treatment many years ago, but never replastered. It looks dry.

Solid walls, 1890's terrace. I get that using hardwall and multi finish is not the right thing to do if there is some damp remaining, or likely to wick through.

So, i was looking at using Limelite renovating plaster and Limelite high impact to give a breathable finish.

The alternative would be Thistle Dricoat and Thistle Board Finish

Does anyone have any experience or forum words of wisdom they can offer?


View attachment 456996

Have you checked for dampness in the floor at the edges near the wall?

 

[JOEPRO]

These threads are all a guess anyway. No one ever takes the time to fully describe the property. Floor construction? All original or renovated? External retaining walls and level differences? External ground finish and drains?

It needs an inspection by specialist and do it right. Or ask for advice and do it cheap which is what is happening here and nothing wrong with that but we are just guessing on what the issues are over the internet based on very limited information provided.

 

[Welderpaul]

My question is about the plaster, not damp.
The plaster was hacked off as a result of a damp issue eons ago, a DPC injected, but the plaster never put back on. There's no signs of damp on the walls, but i'm slightly hesitant to stick gypsum plaster on the walls.

 

[julianf]

This property has had damp treatment many years ago, but never replastered. It looks dry.

Our lounge has dry walls.
When they were covered in multi finish they had things growing up them.

It's akin to "I didn't know you had dandruff..."

You don't have a damp problem. Cover the walls and you might...

I know nothing of the products you mention.
The main issue with lime is that it's way harder to get the same finish as you do with gypsum.

You may be able to get a lime finishing plater with a tighter grain if it bothers you, but this would work best as part of a system rather than as a second thought - mainly as you want to be applying that sort of product in a thin skim on top of a very recent prior layer.

Most (not all) of the time, a "wet on wet" application works better than letting the prior coat fully harden and dry.

I don't know the system you mention but if it is a "system" then you would think that it would be thought out and work ok.


Again, I would caution about happily thinking there isn't a damp problem. There is no damp problem at the moment...

 

[Welderpaul]

You don't have a damp problem. Cover the walls and you might...

Yes, this is my concern/thoughts. At present the walls can breath, if i stick gypsum on there they can't and i might get problems.

 

[julianf]

I've just looked at the products you mention -

They're going to be an NHL based pre mix, I'm sure.

I've used the, umm, reabilita ca (or somthing like that) from Mike wye a fair bit, and i reckon what you're linking to is pretty similar.

The cost on the link you sent is high - I don't know if Travis will discount you, but if you are paying list, then you may want to compart to the mike wye pricing even with delivery.

They are pretty slick on the sales - you can call them, tell them the substrate, and the area, and they will click some buttons and you get emailed the product list in the quantities etc.etc.

I'm sure they would list their NHL concoction that I get the name wrong on, followed by a 1mm skim of a fine grain putty.

 

[julianf]

This is the stuff I'm on about, but it seems they have more variants than when I last looked -

On a very brief read, it looks like the RB at the bottom right is for the harling coat, followed by the AC and then the ac fino as your finish.

I've used the middle product with a different base and then a fine 1mm putty skim before but I'm getting more into NHL mixes. You need to build them wet on wet and trowl them hard to reduce cracking, but I'm currently liking them more than putty.