Mould Problems - Only One Bedroom

[Pocah]

You need to strip all the decorations, clean and then apply a coat of Thompsons One Coat Damp Seal or Zinsser BIN ( Shellac based paints ) to all surfaces in the room. Walls and ceilings, so that you go at least 18" past any signs of damp. Then you can decorate. The Thompsons is easy to use and you can happily roller it and get perfect results.

Since you haven't been able to find any reasons then guess here is that your external wall paint has become porous and thanks to the terrible amount of rain we had in the winter the wall is now saturated. Vapour can cross a cavity even if it is insulated. There have been a lot of problems with people reporting old damp areas causing problems again. My answer to this is always to paint the exterior with a Pliolite based masonry paint such as Johntone's Trade Stormshield Pliolite. Should last you at least 15 years.

 

[jpaul]

Since you haven't been able to find any reasons then guess

he updated us ?

 

[Admiral Huddy]

I know you said your home had wall cavity insulation before you moved in, but it's the worst thing we had done to our home. Granted it's lovely and warm in the winter but the problem is the house is like a tuppa-ware box.. The moisture just can't escape so we get area of black mould in a few corners of the bedrooms which we never had before.

I have to apply neat bleach in the area every few months. We also bought a de-humidifier to help combat the moisture when we put cloths out to dry and have baths/showers. I also have a number Uni bound moisture traps too.

Unfortunately we can't undo what's been done. In hindsight, I would have never have had it done had I known.

 

[Pocah]

he updated us ?

I will look....

I'm a little unclear whether you are saying its only the dividing wall or an external wall.
OK you say the insulation is foam? Then it is sort of the insulations fault. The problem is that foam insulation is waterproof. Normally house walls absorb all the pints of moisture you kick out all the time but with foam insulation it has nowhere to go. So back to my original comment, the treatment of the inside if fine ( a coat of Thompsons One Coat Damp Seal before you decorate ) but you must also vent the house. In any room where there is long occupation, cooking, anything that builds up water and there is no ventilation you will get a problem. If you are getting this in a bedroom then drill a hole right through the wall to the outside world and pop a vent cover inside and out.
If the dividing wall is the problem then you should be able to get away with a coat of Thompsons, without having to do anything else.
I am unclear why the rendering should need attention. It looks fine. Other than the fact that it may be porous, in which case it needs some fresh paint.
I am still a little confused by the report becuase if the insulation is injected foam then the state of the rendering is irrelevant. Maybe you can clarify this. ..

 

[Solus]

I think I've found the source of the problem.

The masonry paint.

Other houses have water based masonry paint which means you can see all of the stipples in the render.

Ours however, I believe has been painted with some form of oil based paint which has created a film over the top. This has not fully adhered to the surface, which in turn has caused many "air pockets" and possibilities for water to sit between the paint and the render. See my video here where you can see a relatively flat looking part of the paint (hardly any stipples):

https://photos.app.goo.gl/te4tfn5dVAvsN3TS9

Most of the wall is like this. Where I peel the paint the render beneath looks sound with no cracks.

I think the solution would be to remove all of the paint and stabilize then paint the render with water based masonry paint.

I think the reason may be that the paint isn't breathable, and moisture is trying to escape causing the paint to blow off the wall?

However, how would I go about peeling off the whole of the paint on the entire front wall?

 

[Pocah]

I think I've found the source of the problem.

The masonry paint.

Other houses have water based masonry paint which means you can see all of the stipples in the render.

Ours however, I believe has been painted with some form of oil based paint which has created a film over the top. This has not fully adhered to the surface, which in turn has caused many "air pockets" and possibilities for water to sit between the paint and the render. See my video here where you can see a relatively flat looking part of the paint (hardly any stipples):

https://photos.app.goo.gl/te4tfn5dVAvsN3TS9

Most of the wall is like this. Where I peel the paint the render beneath looks sound with no cracks.

I think the solution would be to remove all of the paint and stabilize then paint the render with water based masonry paint.

I think the reason may be that the paint isn't breathable, and moisture is trying to escape causing the paint to blow off the wall?

However, how would I go about peeling off the whole of the paint on the entire front wall?

I don't think that is your problem!
I just looked at your photo and you have injected foam insulation.
That is known for causing damp problems. Thing is that injected foam is waterproof. I think you mentioned something about work being done on the house? New plastering? Well, there is one possible cause. A second is poor ventilation. A third is the damp party wall. So I don't think it has anything to do with the rendering.
What I would do is increase the house ventilation by popping some vents in to the rooms that need them. THen treat all the afected areas particularly ALL of that party wall with a damp sealant such as the Thompsons one coat.

 

[Solus]

This is the conclusion CIGA came up with, which is why i'm messing around with the wall.

Further to your contact with CIGA and a subsequent inspection of your property completed by a Knauf Insulation representative on CIGA’s behalf, we would like to comment, as follows. The CIGA guarantee provides assurance that defects with workmanship or materials in connection with the installation of cavity wall insulation will be rectified free of charge for a period of 25 years from the date of installation, but this does not include indirect loss, damage, costs or expenses. Furthermore, following the installation of cavity wall insulation it is the responsibility of the homeowner to ensure that the outer wall surface, including perimeter window and doors seals are regularly maintained in order to prevent water ingress and consequential internal dampness and decor damage. The inspection has identified significant fracturing to the render wall surface and particularly across the front elevation where there is evidence of water ingress and décor damage. Despite one or two small void areas, surrounding cavity wall insulation was found to be uncompromised and the dividing wall between properties appeared to be the most affected area but not treated with injected cavity wall insulation. Under the circumstances CIGA would suggest that external defects are rectified as a matter of urgency and this may be sufficient to avoid furthermore damaging water ingress. Under the circumstances CIGA is unable to be of any further assistance in this matter. If you are not happy with the outcome then the Guarantee includes an arbitration provision and, accordingly, if there is a dispute then the matter can be referred to the independent ADR scheme operated by the Centre for Effective Dispute Resolution (CEDR).

 

[the_r_sole]

worth paying to have the insulation removed imo

 

[Solus]

This photo clearly shows the differences in the wall coating and what I mean by how the paint is pulling away.

https://photos.app.goo.gl/ksLEDMVU62qkmZ1N9

 

[Pocah]

Well I am a little mystified as to where the water is getting in, but anyway, I would do the following... ( cheapest way )
1. strip all the affected internal rooms and give them a coat of Shellac based paint like Thompsons One Coat Damp Seal.
2. get a 4~5 " grinder with a few stiff wire brushes and some thick leather gloves and remove all the paint from the front of the house.
3. fill any cracks in the render OR if you really want to go totally mad then paint the front of the house with tanking slurry! ( its a cement based mush that you paint on with a brush and it's waterproof)..oh don't do this unless all the paint comes off though.
4. Repaint the front of the house.
5. You might like to add a few air vents to the worst affected areas of the house or at least leave the windows slightly ajar for a long while to give the house time to dry out.

I mean basically this is on the cheap but it will work.

 

[Solus]

Well I am a little mystified as to where the water is getting in, but anyway, I would do the following... ( cheapest way )
1. strip all the affected internal rooms and give them a coat of Shellac based paint like Thompsons One Coat Damp Seal.
2. get a 4~5 " grinder with a few stiff wire brushes and some thick leather gloves and remove all the paint from the front of the house.
3. fill any cracks in the render OR if you really want to go totally mad then paint the front of the house with tanking slurry! ( its a cement based mush that you paint on with a brush and it's waterproof)..oh don't do this unless all the paint comes off though.
4. Repaint the front of the house.
5. You might like to add a few air vents to the worst affected areas of the house or at least leave the windows slightly ajar for a long while to give the house time to dry out.

I mean basically this is on the cheap but it will work.

Thank you very much!

The type of insulation was Knauf supafill to answer your previous question.

I shall get some holes drilled and vent covers placed inside and out after the wall has been blasted and painted.

I don't really have the time to do all of this myself, so I am going to call round to get some quotes.

 

[Solus]

Had a plasterer out today and he advised going over the top with mesh and k-rend.

Unsure if that's the best of ideas as the paint isn't sound?

 

[Solus]

Unsure what the going rate is for a wall of this size (7m wide) but he's come back with £4800 for k rend over the top or £3500 to hack off and sand cement render.

Seems steep for one wall?

 

[jpaul]

The CIGA comments suggest the issue can be further arbitrated if you are not 'happy' with the resolution,
so is there any basis on which you can say their(whose?) initial survey and recommendation to install the spray foam was incorrect for your property.

Their reply does seem very draconian in trying to attribute all the 'blame' on you.

 

[dholdi]

Do you share a chimney with your neighbors on the party wall ?
Sorry if its already been covered, just skim read the thread.

 

[thezappa]

Couldn't tell you a price for the rendering but hacking it off is a messy unpleasant job especially over a whole wall of that size.
Also re-rendering doesn't necessarily fix the problem - just saying, but if it is facilitating the problem it will help. Have you done any investigation in to the roof, could be a possibility of ingress there (can't see if you mention the position of the chimney or the condition of the roof).

 

[Solus]

The chimney has been taken down below roof height and exists still in the loft.

The chimney is not on the party wall.

As I've now chipped away at the paintwork and jet washed some of it the wall looks ugly. Something needs to be done anyway as the paint is coming away like wallpaper.

The roof doesn't seem to have any fault and the neighbour's wall has been checked recently to be fine. If I could I would patch up the cracks in the paint and paint over the top, but this isn't possible as the paint isn't sound.

I've got a general builder I've used before to come take a look tomorrow or Friday.

 

[eviled]

Is it a cavity party wall ?

 

[Solus]

Yes it's a cavity party wall.

I've realised that cracks in stucco render are fairly normal from reading up, as long as the render isn't blown then I can patch things up (I was a bit apprehensive that it was going to be a botch job before).

This is about an hour's work with the jet wash:

https://photos.app.goo.gl/BdRjuZPqygp8gimU9

Just to test, I tried to get some paint off the porch and couldn't, whereas the house comes off in small sheets in some areas.

One main question, should I focus and try to get ALL of the paint off? Even the stubborn bits? Or is it a case where I can leave them on and use stabiliser?

 

[jpaul]

(maybe others will comment) I would be carfeul with a jet wash, I played one on a previous rendered property I had N/side with algae, and can damage/erode render surface.
that's why I thought Pocca was suggesting mechnaical removal for paint.