Damp Patches on Entire Wall

Ben1989

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.

YoungBlueEyes

I am not the expert here.

How old is your house? Might it be worth having a look at this website?

www.heritage-house.org 

ThisIsWeird

Not an expert either, but the two obvious patches in the first pic look like 'penetrating' - coming through from the outside skin - quite focussed at these points, although water can travel tortuous courses before finally appearing.

The damp in the second pic is more general, but could still be penetrating, but dispersing over a wider area as it appears through the plaster. Or, it could be condensation.

The window reveal also looks penetrating - actual water from the outside getting through, quite possibly from where the window frame joins the wall.

The render 'looks' ok from that photo, but you cannot really tell. If it's blown anywhere, it can trap water and spread behind it and come through it different places.

No idea on the best approach, but for lawdie's sakes add insulation to the inside wall this time - you missed an opportunity.

It 'may' require (I don't know) something like a lime render so the wall can breathe to the outside, possibly tanking the inside to simply prevent any coming through, but then Def a layer of insulation board (as thick as you can get away with) before a new skim. That would be money well spent.

stuart45

It could.be a combination of penetrating damp and condensation. To check for likelihood of condensation forming, you need to know the temp and R/H of the rooms, and also get the surface temperature, with a surface thermometer.
It's a really exposed wall, so as TIW said, insulation would be a good idea.
Damp areas tend to be colder than dry ones, so these places will keep on attracting more condensation.

FreeBear

ThisIsWeird said: It 'may' require (I don't know) something like a lime render so the wall can breathe to the outside, possibly tanking the inside to simply prevent any coming through, but then Def a layer of insulation board (as thick as you can get away with) before a new skim. That would be money well spent.

Not enough space in the stairwell to add insulation to the inside wall without moving the staircase (a major undertaking). EWI would be the better option, but that would require extending the window sills & moving downpipes.

The bedroom, certainly add IWI and make sure it is wrapped around the window reveals. There is a big hole at the bottom of the window - Bet that is a source of a nasty cold draught. Cut a Thermalite (or similar) block to plug the hole.

The penetrating damp really needs to be sorted first - If there are no cracks in the render, the roof is in good condition, and the downpipes are not leaking, that just leaves one potential source. Window frames. If these are not very well sealed against the wall, there is scope for wind driven rain to get in. But I wouldn't expect huge volumes of water to get in, so not entirely sure that this would be the primary source of the damp.

flashg67

Having bought an old house 2 years ago, I'm still learning,  but have found that modern gypsum based plasters and latex paints aren't good for older houses with solid walls. I've taken some time to test areas using lime plaster in places and even just removing the standard emulsion and using lime wash in its place which so far is reducing the mould patches. 

ThisIsWeird

FreeBear said:

Not enough space in the stairwell to add insulation to the inside wall without moving the staircase (a major undertaking). EWI would be the better option, but that would require extending the window sills & moving downpipes.

Not quite easily workaroundable? It's only the staircase string that needs modifying. (Mind you, all the damp could then be focussed between that and the wall...)

But, yes, since the exterior doesn't have a particular aesthetic, then EWI would be better in a number of ways. Would the existing roof overhang cope, or are these extended? That would sort any penetrating too.

plumb1_2

You can fit some 50x50 timber on top the casing and then insulate the wall.

MikeJXE

When you had the scaffold up did it rain much and did you turn the boards back nearest the house ?

Ben1989

Thanks all for your input. Something came up after I posted so wasn't able to comment straight away. 

So, yes, IWI would be an issue and would require a large undertaking. Also EWI would require a large undertaking and we're likely to extend in maybe 4 years so can see half of it being ripped off.

Not quite sure which way to go. Could it be both? Say we render and it solves nothing, or only reduces by 20% and we're thrown all our savings at it. Equally, I'm worried if we solve it from the inside, am I just moving the problem out of view? It's ALL over that wall which makes me think is it really penetrating damp? Also, nothing to go off, but not a single house has had it's gable wall re-rendered.

Mike, it was one of those rented towers from HSS so no boards. It was during the second summer heatwave (was hard work)

Apodemus

I can't see any rational reason to "tank the wall", although it is almost certainly what most damp conmen "experts" would want to do.  If the issue is condensation on the inside, then the tanking is external to the problem and tanking won't help.  If the issue is penetrating damp from the outside, then it is still there, accumulating in the wall behind the tanking - and you don't want that either!