Damp patches, bubbling paint after damp works....

[markwm]

Property: brick mid terrace, cement rendered..

I injected the exterior wall of this mid terrace property with Dry Zone over 2 years ago. Internal plaster was hacked off, treated with salt solution and then Thistle Dry-Coat(cement based) was used, then a finish coat of multi finish.

The wall was left well over a year before ANY paint was applied. Only got round to painting it say 6 months ago. Paint was soft sheen.

Last few weeks noticed some bubbling paint patches, the artic weather hasn't helped :-(

They're isolated patches and quite high up, the worse you can clearly see as I've sanded off the bubbling paint, the wall doesn't even feel cold. On the other side on this wall is next door! Only just noticed the other two patches today. This wall is north facing and is at risk from damp as it takes a long time to dry out being.

The exterior wall is free from any cracks or defects that would allow water to penetrate. I'm convinced it's brick salts that's the problem, salt problems persist throughout these houses and it seems almost impossible to treat without removing the affected bricks.

Luckily this is the one area of the house at this level that hasn't been dry lined, reason being it's tricky to do being on the stairs. So, I need advice on a solution. My thoughts....

1. Suck it and see temporary solution....Sand off the flakey paint, apply some damp seal and paint over.

2. Board over or clad the affected area. It's only a rental so never going to be a show home. At the moment the plaster is rock solid. My only worry with this solution is that over time, will the plaster turn to mush, thus loosening any fixing used to fix the cladding...?

3. Hack off back to brick up to a level then dry line, either with treated timbers or with plaster membranes. I would use some kind of bead or dado rail to hide the join between the plaster above and the dry lining below. This being the worst case scenario.

 

[markwm]

Same area before plastering:

 

[Matt Green]

I'm convinced it's brick salts that's the problem, salt problems persist throughout these houses and it seems almost impossible to treat without removing the affected bricks.

Really? Water is traveling through impermeable paint and cement plaster being absorbed by the bricks, drying and then moving back through the plaster and getting stuck behind the paint and causing it to bubble?

What are the floor/ground levels on the other side of the stairs (main flight and first few steps)?

Also, this product: http://ukconstr01.webdms.sika.com/fileshow.do?id=554, whilst not being environmentally fantastic has proved useful for specifications where salt damage is a real issue (focussed applications: chimney breasts, animal houses, fertilizer stores). Better than switching bricks.

Matt

 

[markwm]

Exterior ground floor level is about 50cm below internal floor level. (That's on the wall where the door is)

The wall on other side of the stair wall is next doors property and that particular wall next door has had all it's plaster removed and was dry lined with timber over bare brick I know for sure.

 

[jocelyn plummer]

Is there, by any chance, a hidden water pipe/mains supply/downpipe/soil stack running anywhere along or near the wall?

We had a similar problem about 12 years ago, the culprit turned out to be a the elderly Neighbours , long unnoticed, steadily leaking water mains, coupled with a broken collar around the soil stack which was causing debris to collect. The water mains pipe, attached to our wall, was running at an angle from their higher garden level down to our ground floor level. Random patches appeared in our wall.

 

[Matt Green]

OK, so next door sound like like have had a similar problem and have dry lined.

Is the external surface of the exterior wall rendered (yours or your neighbours')? Is the floor in that room solid and is it the same on your neighbours' side

What's under the stairs? Are they timber construction, or timber treads and risers over solid?


Matt
-this is getting close to the 'needs a site visit response'...

 

[Moo]

Property: brick mid terrace, cement rendered..
I injected the exterior wall of this mid terrace property with Dry Zone over 2 years ago. Internal plaster was hacked off, treated with salt solution and then Thistle Dry-Coat(cement based) was used, then a finish coat of multi finish.

??

 

[Matt Green]

??

People do these things. What's done is done. Breathable plaster and breathable paint would have been the first choice solution, but I hope the OP knows that having read the forum for a bit. cDPC with cement and water is still moving through it. The wall could be drying, slowly, or there could be something more sinister afoot.

Damp threads: generally pretty dull* and the answer is usually only a forum search and bit of googling away, but I live to serve.


Matt
*you know it's a dull thread when Joce hasn't commented.

 

[Penners]

I live to serve.

Gin & tonic please.

 

[JoceAndChris]

Peach bellini please.

Damp threads: generally pretty dull* and the answer is usually only a forum search and bit of googling away, but I live to serve.

*you know it's a dull thread when Joce hasn't commented.

:!: I like damp threads too! Especially with your learned responses - I just don't want to start diverting into irrelevancies when it's important!

 

[markwm]

OK, so next door sound like like have had a similar problem and have dry lined.

Is the external surface of the exterior wall rendered (yours or your neighbours')? Is the floor in that room solid and is it the same on your neighbours' side

What's under the stairs? Are they timber construction, or timber treads and risers over solid?

The external surface of both properties is the same, unpainted sandy-cement render. you can see the salt lines and discolouration on it low down but it's rock solid and impossible to remove. They're to be painted this year and I think I've already settled on Beecks mineral paint to do the job. Did a test with limewash as it was a no go.

The floor in the neighbours room is solid, stone over earth contained over a vaulted cellar.

Underneath the stairs in my house is the cellar. So the kitchen floor stops at the first step and after that it's a void of maybe 6ft to the cellar floor. Stairs are indeed timber. Think I might try the dryzone again from the inside(i can access under the stairs). The problem is the brickwork is so bad the mortar beds are all over the place.

edit: This is a picture of the neighbouring room next door, the area where the damp is on our side is in the bottom left of this picture.

 

[Matt Green]

Several things:

Is that dark patch on your neighbours' wall the staining from a removed chimney? If it is then salt contaminated brickwork is indeed the cause. The air in the lining void will lose it's water to the wall and can't get back in to the void because the RH is too high.

Silane cream will do nothing for salt contamination. It's arguable that there isn't much likelihood of ground water rising through that wall anyway because there's a vaulted cellar beneath. Unless they have both been tanked, i suppose.

I think the wall is either drying down (still, due to all the cement), or constantly gaining water and losing it due to salts. I would leave it alone and maybe repaint with a more breathable finish that wont bubble. Obviously some water is moving through your plaster: it may as well do so unimpeded. Either way I doubt the silane cream is doing much in this case, but you would need an invasive survey to find out more.

Matt

Peach bellini please.

I can whip you up a pint of diesel with a cocktail umbrella? There should be enough for a round as long as Penners' paces himself.

 

[markwm]

The dark patch is indeed from where a chimney was removed BUT this is not where the damp on our side is. The damp is where the chimney recess used to be(see the wire on the pic? there), so there are no sooty bricks on the other side.

That chimney, when it was removed(it had been bricked up for years) revealed massive salt damage to the bricks at the base, whole bricks had turned to dust and you could put your hand through from one house to the other.

Where the back of the chimney is on our side I used another dry lining system which i think was the best option and had no problems thus far. Thank you for your responses btw.