Damp Patches on Entire Wall

[BenH1989]

Hi all,

A bit of background. Had artex everywhere when we bought the house. Decided to get it all scraped off and skimmed on the gable wall so hallway, up the stairs and the landing. Allowing the plaster to dry for several months we decided to paint it.

But, numerous damp patches have appeared on the entire wall. It is a solid brick wall (i.e. no cavity). It's a 1935 house.

In the box room at the front the plaster on the wall is blown (not artexed and skimmed).

I have had scaffolding up for a week and filled in all the holes and cracks I could find and also repainted with sandtex. I struggle to see how it's really penetrating. There is also no guttering on this wall. All the houses on my street (about 25 in my style) none of them have had the wall re-rendered.

I have had a rendering guy look at it who said it's the rendering. I have also had a damp guy say it's the nature of the house and the plaster will need removing, cleaning and tanking the wall, plasterboarded and re-plastered. Two totally different opinions, both £5,000.

I have installed a PIV to hopefully help but hasn't seemed to affect the wall.

I don't want to spend £5,000 on something that doesn't work/help. I can't afford both. But it's the ENTIRE wall. Upstairs and downstairs.

After any advice.

Thanks in advance.

 

[blup]

The artex has trapped damp in the wall that the damaged render let in. Removing it has let the damp through to the plaster which never had a chance to properly dry out. The blown plaster in the box room suggests the artex was removed and replaced by a previous occupier. There are two basic contradictory opinions about damp in walls, tank them, or let them breathe. Whichever you go for it is worth getting in an building surveyor for an independent professional opinion for site specific nuanced recommendations. It is just possible that there were historic leaks of water onto the wall, the sources of which have been removed or addressed (e.g. damaged or broken roof tiles which dripped onto the render over many years).

The other (additional) thing to bear in mind is that the house may have been cold and damp from years of internal neglect and misuse.

Cost aside, I think I would be tempted to insulate and add stud walls internally for the energy saving aspect, but £500 or so for a survey would be money well spent, just get the right person.

Blup

 

[Loofah]

Are you able to strip the render and insulate the external wall? May be cost prohibitive though

 

[tell80]

OP, I'm telling you bad news but thats my opinion based on what I see & what you say.

You have penetrating damp and a little condensation.
The render is the main suspect - there are a few patches where a bit of previous remedial work has gone on.
Did the visiting plasterer mention cracks in the render?
There's also the lean-to shed roof, and any abutting shed walls - & probably the shed flashing, all might be assisting water penetration of the gable?
The good bits are that the window & door frames are well set back and covered with Bell Cast's.

All the items above will need attention.



Best practice says all water damage & damp signs on the internal wall will need to be hacked off - they wont fade away.
Remedial patching will work - but the surrounding plaster might present damp signs in the future, so hacking off all or most of the gable interior plaster is the way to go.
After hacking off, leave the bare brickwork for a lengthy period to dry out.
Use trickle heat & trickle ventilation.

Best practice further says that all the gable render should be hacked off, and the brickwork re-pointed.
Use a render mix of 4:1 sand & NH lime for both internal and external sides of the gable - same mix for the pointing. Use Limlite finish.

Dont use any gypsum plaster - no waterproofers or admixtures required - no tanking needed.

 

[BenH1989]

Thanks all. Very interesting and enlightening replies. We’ve had another damp guy round and he said it’s historic damp stuck in the walls and now able to dry out (albeit slowly) through the new gypsum. He personally thought the render wasn’t actually too bad and no major cracks at all. He suggested hacking off the internal plaster, letting it dry for several weeks, and then tank, board and skim. Does he have a point? Then I asked IF there is penetrating damp what happens? He said the brickwork will just remain wet. Can’t be good?

He said maybe in a few years then do the render but I’m tempted to hack it off and leave it off eventually.

The box room with the plaster hacked off has had months now to dry. I bought a moisture metre and that brick reads the same percentage as the ‘wet’ internal gable plaster. I’d have thought it’d be lower. But maybe the brick behind the plaster is significantly higher

 

[blup]

He's half right IMO, chop it off and dry it out but don't tank it because by definition there is nothing to tank. Just re plaster.

Blup

 

[BenH1989]

He wants to tank to block any moisture coming through to the new plasterboard/plaster

 

[foxhole]

Given how narrow the sills look you may have render on top of render making it very effective at trapping moisture , could takes months to a year or more to dry completely.

 

[BenH1989]

I'm not sure where to go. I'm a supporter of do jobs properly but at the moment there's moisture and mold on the walls.

 

[blup]

You risk damp/mould coming through if plasterboard is attached direct to the wall, if there is space you could put up studwork with moisture resistant fixings.

Blup