Had a guy look at my daughter's house - it has a damp wall despite having previously been injected.
He suggested fixing on Newton Membrane. However, the overall quote was silly and I was wondering if I could ask my usual plasterer to apply the membrane and plaster as usual. He has no experience of such membrane.
I wonder if there is a readily available membrane; does plaster adhere to it - or does it need to be plaster-boarded? (not keen on battens as the problem is below the dado rail only)
Whether it's this or rising damp, sealing the inner surface is the way to make the wall even damper, with damp spreading laterally. Definitely a bad idea with a suspended floor if the joists go into the wall.
IIRC, it's only usual to use that sort of fix in a cellar where it's impossible to keep water off the outside walls. In all other cases it's better to stop the damp penetration. And that's most usually what it is - not rising. Can you give more details?
The house is a 20's / 30's build. The damp is on a party wall near a chimney - blanked off - hit & miss vent over hole - always open. Suppose it could be rain penetrating chimney brickwork and getting down chimney. My first fix was dab and dobbed P/B. I could have taken it too close to the floor (solid). Damp could have been old salts as council later did some work to lay Acco Drains on pavement as the houses are slightly lower than the road. Area used to flood to a few inches in heavy rain. Fixed about 6 years ago. I dealt with wall at about the same time.
With plaster stripped off it feels dry to the touch.
I agree that tackling the source of damp Is essential. However the use of membranes can be part of the solution. Although on this case the OP has some distance to go before jumping into a "fix" of using a membrane.
It's clear the silicone injection hasn't worked, so the reason for that needs checking to see if it is penetrating from outside to inside or as a consequence of poor roof maintenance.
I've used external and internal membranes from Delta for rooms where the wall is part buried in soil. The internal ones are deigned with a ventilation air gap. Fixing them isn't difficult but needs to be done using appropriate fastenings. Delta provide excellent tech support and the membranes are relatively cheap.
I've sorted a real problem wall (24 inch rubble fill random stone, straight on wet limestone at the bottom of a hill) by taking off all internal rendering, repointing nicely with lime mortar, and putting ventilated T&G wainscotting, well spaced on tanalised battens, over the bottom three feet.
uk.d-i-y First bit of advice... Check if the bloke has any qualifications to make such an assertion. Is he CRDS or bettter still CSRT. Even with such qualifications your chances of getting a sensible answer are limited for several reasons: a) it is not difficult to pass these exams with only a 50% pass rate so that means that a bloke is qualified for only knowing half what he or she should b) you have to be a moron in a hurry to fail if you are half way to being able to read and process information and can memorise c) the exam is not a substitute for commonsense (I could go on but its not the issue here) Alternatively, if not qualified is he competent by experience? How many years of good work for a good firm has he done? Absent one of the above discount anything he says!
Now go back to basics There are four types of 'damp': rising, lateral penetration, condensation and pipe leaks. This is on a party wall if I am reading it right. It is not going to be the last two so we are left with rising damp or water leaks from above The latter is most unlikely and can be determined by following with a damp meter in the masonry from above If it is within a metre of the floor and has a characteristic high tide mark it could be rising damp but you say now you have stripped off the plaster that the brick is dry. Ipso facto no RD. It WAS probably hygroscopic plaster caused by fossil fuel burning SO2 gas goes to SO3 plus water then SO4 (sulphates) then hygroscopicity. Getting rid of the plaster solves the probelm
Do not use Dot and Dab as it is a gypsum based glue Suggest a 3 to 1 sand cement render or metal laths and plaster Send photos etc and I can comment on our pro bono terms
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