Very very wet wall - Can I paint it?

[montyjohn]

I'm buying a G2 listed property.

It's been neglected for some years and one wall is saturated where the gutter has been pouring down the external brick.

The guttering was temporary repaired back in January, but the wall is still very wet to the touch and will likely take a few years to dry out.

When I move in I'll test the plaster to confirm it is lime. I'll try the old vinegar test but I think it is lime.

But I also want to make it look less like an ecosystem is growing on it whilst it's drying out.

I was hoping to remove the modern wallpaper, with some light abrasives to remove the various species of mould along with some sugar soap.

And then lime wash it, and just monitor it for a few years.

Is this the right approach? Is lime washing it a waste of time?

It's listed so I want to avoid taking it back to brick as I will need consent for this. If the plaster is toast, I will obviously have no choice, but if it can be saved I want to try that first.

Anybody experienced with lime that can share any tips?

I'm going to gently warm the room this winter, with windows slightly open for decent ventilation. Will avoid dehumidifiers as this can cause the outer layer of lime to dry too quickly, then it blows off. Or so I've been told.

 

[Cubist]

Sorry but there are a few elements here that are intriguing me. You've been told the gutter was temporarily repaired back in January but the wall is still sodden. Is it safe to assume then that the repair never worked or has failed again at some point since? All things considered we have had a remarkably dry year so far and the walls exterior surface should have had ample opportunity for evaporation and gravity to either wick away a lot of that moisture or for it to descend to lower sections of the wall. Is this wall on the Northern side of the house and is it sheltered from wind/air movement by any chance?

Or; is the very wet wall apparent indoors? If so then I would be surprised and puzzled that the wallpaper is still sufficiently firmly attached to the plaster to merit more than some gentle teasing with a scraper to remove it and with the paper any moulds residing on its surface. I'm also unsure why you would need or want abrasives and sugar soap to attack the wallpaper? It is sometimes necessary to abrade the surface of a washable or vinyl wallpaper, and/or where the paper has been coated with a washable paint of some kind, to rupture its surface to then allow a soapy water to penetrate and soften the papers bond to the plaster. But if the plaster is already wet due to rainwater penetration from outdoors then this seems rather pointless.

After stripping the paper and eliminating any moulds no useful purpose, in my opinion, would be served by then whitewashing the plaster. Frankly if the wall is that wet you will be lucky not to lose considerably more than a few patches of the old skim coat and some small elements of the underlying render coats and your best option then is to leave the raw plaster surface exposed to aid evaporation to the internal atmosphere and thereby the drying out of the wall. However, the passage of several years will not be required before you could begin making the paster surfaces good. Assuming the external issue of rainwater penetration is properly resolved, gravity and good airflow through and without the building should cut that timescale to less than a year.

Regarding my preceding point, I appreciate your concerns regarding the use of dehumidifiers but you may want to reconsider. Yes, these can induce blowing of 'new' lime plasters but maybe the differential movement phenomenon induced in such circumstances could work to your advantage and further reduce the elapsed time to when you can repair the plasterwork. Running such a device in the affected room could very well cause much of the old plaster to 'naturally' separate from the masonry to then allow you to make 'like for like repairs' which would then not require full LBC approvals?

One other point you seem not to have considered. You don't say whether the affected rooms also have suspended wooden floors. If they do you should also examine the state of the floorboards adjacent to the walls in question and, if necessary, lift a few to examine the joists. If the joists are mounted in pockets in the wet walls they could have suffered quite badly and intervention there may be essential sooner rather than later.

 

[montyjohn]

Sorry but there are a few elements here that are intriguing me. You've been told the gutter was temporarily repaired back in January but the wall is still sodden. Is it safe to assume then that the repair never worked or has failed again at some point since? All things considered we have had a remarkably dry year so far and the walls exterior surface should have had ample opportunity for evaporation and gravity to either wick away a lot of that moisture or for it to descend to lower sections of the wall. Is this wall on the Northern side of the house and is it sheltered from wind/air movement by any chance?

Or; is the very wet wall apparent indoors? If so then I would be surprised and puzzled that the wallpaper is still sufficiently firmly attached to the plaster to merit more than some gentle teasing with a scraper to remove it and with the paper any moulds residing on its surface. I'm also unsure why you would need or want abrasives and sugar soap to attack the wallpaper? It is sometimes necessary to abrade the surface of a washable or vinyl wallpaper, and/or where the paper has been coated with a washable paint of some kind, to rupture its surface to then allow a soapy water to penetrate and soften the papers bond to the plaster. But if the plaster is already wet due to rainwater penetration from outdoors then this seems rather pointless.

After stripping the paper and eliminating any moulds no useful purpose, in my opinion, would be served by then whitewashing the plaster. Frankly if the wall is that wet you will be lucky not to lose considerably more than a few patches of the old skim coat and some small elements of the underlying render coats and your best option then is to leave the raw plaster surface exposed to aid evaporation to the internal atmosphere and thereby the drying out of the wall. However, the passage of several years will not be required before you could begin making the paster surfaces good. Assuming the external issue of rainwater penetration is properly resolved, gravity and good airflow through and without the building should cut that timescale to less than a year.

Regarding my preceding point, I appreciate your concerns regarding the use of dehumidifiers but you may want to reconsider. Yes, these can induce blowing of 'new' lime plasters but maybe the differential movement phenomenon induced in such circumstances could work to your advantage and further reduce the elapsed time to when you can repair the plasterwork. Running such a device in the affected room could very well cause much of the old plaster to 'naturally' separate from the masonry to then allow you to make 'like for like repairs' which would then not require full LBC approvals?

One other point you seem not to have considered. You don't say whether the affected rooms also have suspended wooden floors. If they do you should also examine the state of the floorboards adjacent to the walls in question and, if necessary, lift a few to examine the joists. If the joists are mounted in pockets in the wet walls they could have suffered quite badly and intervention there may be essential sooner rather than later.

Thank you for your detailed response.
Here is a plan view, with red showing the areas of the damp.

So it's actually an internal wall that has mostly suffered. Both first floor and ground floor.

As for the wallpaper it is falling off this wall. It's the mould I want to gently scrape away without damaging the plaster (which may be shot anyway).

I spoke with the vendors' nephew (just bumped into him when viewing) and he explained the repair he did. The whole place is in very poor condition after being empty and everything needs sorting, so I don't think he would have lied.
He said the spout from the gutter had fallen away so water wasn't going into the hopper and was running down the external wall. There is some slight evidence of staining eexternelly but not as much as I would expect.

It may well still be leaking, but all looks to be in place.
The gutters all need sorting anyway, plenty cracked sections of guttering elsewhere so I'm not worried about it, more that I want to ensure water isn't still being added to this internal wall.

When you look at the water damage internally, it fans out where it's clearly pointing to a source at the eves. The fan then gets wider as you travel down the property. So I have no doubt where the water has come from, the damage makes it very clear.

I can only assume there are large voids in the internal wall and water could freely travel through it. Or it really has been going on for many years. It was under an agricultural lease where the tenants had responsibility for maintenance, but didn't own it, so naturally didn't care.

As for the floor, one of the effected rooms downstairs is solid, the other is suspended as there is a basement below. There is some bounce to the suspended floors so joist repairs are expected.

Whether it's still getting wet, it didn't appear to dry at all between first viewing in March, and a following viewings in May and June. I don't think it rained at all during that period so it almost didn't matter if it's fixed or not, I know it's drying very slowly (if at all). Windows all closed, and blankets shoved up the chimneys doesn't help (I was cheeky and removed one I could reach, shhhh). It's also empty and has been for a couple of years now. Water is also turned off so I know it's not a pipe leak (can't wait to turn the water on, that will be fun).

The lack of extensive damage on the external wall's internal plaster probably points to your original suspicion that the natural wicking of the wall externally should have dried it by now. And I think on the external wall it has as you suggest. Internal wall however needs a lot more help. More than I would have expected.

I'm particularly frustrated at the moment as I'm very close to completion and the vendors are dragging the completion out and I just want to get in there, open some windows, free the chimneys and get some heat into it. I'll do some research on the dehumidifiers.

Whilst we won't use these rooms for anything in the short term, if white washing them could make them look a bit less of a state for now, I'd be happy to do it. But I don't want to do it if it could slow the drying time.

 

[Cubist]

I would suspect that the problem is driven rain and windswept outflow from the gutter being pushed under the fascia/soffit boards to then track across the top of the internal wall before descending to either side. The external wall however would not necessarily be of a cavity construction as that would restrict/limit the volume of water appearing in/on the internal wall. Another possibility may be a leak through the roof in that area and may be worth checking out - easier to do if you have access to any loft space. I would be worried about 'scraping' any moulds and recommend that you use suitable PPE for any such work and while you're getting rid of the old wallpaper. Better to trying washing the mould off using a solution of warm water and bleach - the additional water won't do any more harm.

Do you know if the internal wall is of a partition construction i.e timber frame clad with say lath and plaster?

 

[montyjohn]

It's a solid brick wall which makes me doubt the idea that it's water running along the top otherwise it would be damp all the way along the top edge.

Unless it's making its way down first.

As it's just in the corner at the top of the first floor next to the external wall it appears to have a focal point origin.

Which is why the hopper pipe falling off story is a good fit.

I've got really good access to the loft. Lots of plastic sheets on the loft floor which I'm sure has nothing to do with a leaky roof

 

[IHateDamp]

I remember reading somewhere that try to dry a wet stone wall too quickly with a dehumidifier can somehow lock in the moisture internally.