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We've had a problem with damp coming through the gable end of our property (built with industrial blue brick).
Having just re-pointed, capped a chimney and spent some time on the roof we're hoping to have cured or atleast improved the situation.
Now at the point of rendering and plastering the walls and looking for some advice on the best way of tanking them so the plaster doesn't pull any damp/staining through from the brickwork. A builder has recommended a bichumen based product that we can render directly onto but in my head this will trap the water in the mortar, being blue brick they won't absorb any moisture so it has nowhere to go... Is that correct/a problem?
Is there a better alternative, some sort of membrane against the wall then plasterboard stood slightly off the wall maybe, or is this a perfectly good solution?
Any advice much appreciated, we'd rather go ott than risk need to re-plaster (again!).
Speak with a plasterer. You might be best using Renovating Plaster. This doesn't use gypsum and is able to cope with high moisture levels without disintegrating.
Monkey spunk.
Is it a cavity wall or solid? If solid, I would think that you'd be better with a porous plaster that allows the moisture to pass through. My experience is with a stone house and we've used lime plaster (inside and out) which has been fantastic.
Rich.
Flexacryl then dry lining would create a barrier, but sounds extreme.
What about external wall insulation ?
Has worked wonders on our shuttered concrete 60's ex-council semi.
Damp gone overnight, much warmer too.
£4k of funding rumoured to be up announced imminently, if your home is classed as [i]hard to heat.[/i]
(Solid walls).
Cheers for the info, the wall is solid though has a chimney for two fire places running up through it. I've a feeling some of the staining is down to that due to the smell and colour.
My parents have used lime on their place so will have a chat with them.
Tramps piss.
Monkey spunk.
I thought that was only good for holding old cars together. Live you learn.
Flexacryl - that's the stuff. Would seem ott but would it'd let the wall breath/stop the staining?
Did think about cladding the wall but have an extension on that side of the house, it needed re-pointing so went for that. Thanks for the heads up on the funding rumour, will do some digging!
Flexacryl isn't recommended for internal tanking [url= http://www.bostik.co.uk/tds/download_tds/Flexacryl/TDS00262.pdf ]Tech Data[/url]
Tanking can make condensation problems worse, which is why lime plaster is sometimes the way to go
I was told by our local plasterer that we could tank or seal the wall using a slurry mix of cement and SBR. You can paint it on the wall then plaster or dot and dab over it.
If you can bear to wait, then since you've only just fixed the water ingress, I would let the wall dry out before you do anything. Then you'd know whether the fix has been successful, and you'd have more options for trouble free plaster.
We've let the wall dry for about 4 months now, last week I took all the old plaster and render off so it's been sat as bare bricks for a while now to hopefully dry it out further.
Looking at the bricks the staining from the chimney is quite obvious and I think this is what was being drawn through the plaster by the moisture resulting in a sticky, tar like residue and stain. Would using something like lime have any effect on this?
I think it's something along the lines of Flexacryl that the builder is recommending, what I was thinking about was something like this…
[url= https://www.twistfix.co.uk/tanking-membrane?uilang=1&povList=231424&gclid=Cj0KEQiAkdajBRCJ_7_j6sCck7wBEiQAppb2i5Fy8zMwB26nNS0CN1-ZHfEDRP_dN5dk7_o7_yzDbB0aAkDP8P8HAQ ]Tanking memebrane[/url]
The SBR is good stuff, as above, it's a synthetic liquid rubber that you used to make waterproof concrete and render. I have used in on damp issues in our basement. You would still need to remove as much of the surface tar before applying anything directly.
The membrane you have linked to is designed to be skimmed on to, there is a cheaper version without the mesh, and you could line with damp resistant plasterboard.
Cheers Neil, I'll look into the SBR stuff. Builder coming round today so will chat through the options.
That was just the 1st link that came up in Google. I was actually meaning the stuff that would be used with plasterboards over the top. In my mind that'd be better in terms of condensations than painting some sort of damp blocker directly onto the brickwork.
This problem is in an upstairs room, I've a feeling if we could be just moving the damp to the room below.
Do you still have visible damp on the internal face? Sounds like it would have been good to run a dehumidifier in there but probably a bit too late now?
IMO it is better to seal the face of the masonry, if there is a space for moisture or condensation to form on the internal face then it needs to be a vented void or have a system to remove the liquid.
As long as the damp ingress has been sorted, it would be better to seal the face of the masonry then create an isolation barrier. If you go down the drylining route, you could incorporate some insulation. A foil or a rigid 25mm layer between masonry and plasterboard would improve the heating situation, 50mm would be better if you have the spare space. Foil backed plasterboard would also make a difference.