Kingspan making my walls sweat?

[bobber]

Hi, Im in the middle of a kitchen renovation project at home and I am having problems with the walls. Exterior walls are 9'' solid brick and I have black jacked them (bitumen paint) to stop any water ingress in them, fixed timber 50mmx50mm battens, infilled these with 50mm Kingspan and covered with 12.5mm vapour check (foil backed) plasterboards. A few days later I noticed water dripping on floor behind plaster board. when took plasterboard and insulation off, external wall was dripping in condensation/sweat?
Is it the case I need vapour barrier as well or is there something happening with kingspan and the black jacked wall????

 

[felstead]

I could be wrong but it sounds like interstitial condensation. The thing to understand is that as air moves through the fabric of a building the temperature will affect the moisture content.

So as the air cools (as it progresses towards the exterior) moisture forms. Every wall construction has a dew point - the point at which condensation forms. Most large insulation manufacturers such as Kingspan can actually calculate this for you to assess how a particular construction is likley to behave.

My guess is that one of two things is happening.

1 - By changing the construction of the exterior wall you have changed where the dew point occurs - ie and it is now occuring at the inside face of the original brickwork.

2. The application of the blackjack paint is preventing moisture from passing through the fabric.

It is posisble that it is actually a combination of the two.

My advice would be to speak to Kingspan's technical department (who are very good) and see what their assessment is. They should be able to guide you.

The other point of that foil backed plasterboard is not a particularly great vapour barrier as it is almost impossible to get a good continous seal. It may be that with a more thorough vapour barrier that is well installed this could overcome the problem.

James

 

[dazdel]

Hi, Im in the middle of a kitchen renovation project at home and I am having problems with the walls. Exterior walls are 9'' solid brick and I have black jacked them (bitumen paint) to stop any water ingress in them, fixed timber 50mmx50mm battens, infilled these with 50mm Kingspan and covered with 12.5mm vapour check (foil backed) plasterboards. A few days later I noticed water dripping on floor behind plaster board. when took plasterboard and insulation off, external wall was dripping in condensation/sweat?
Is it the case I need vapour barrier as well or is there something happening with kingspan and the black jacked wall????

Classic, In more time there will be more of these problems on forums.
1. you have killed the walls ability to breath.
2. there is no space for air, or very little.
3. kingspan is foil backed, and so is the plaster board, any change in temperature, whether the outside wall or inside, will attract condensation and run down the foil. If it was my problem i would remove the kingspan so to create a void of air, this may help. The black jacked wall is the probable cause, because before the wall could breath (absorb moisture in the air, breathing in, and breathing out. As this is no longer possible you have this problem. A few years ago saw a similar problem, but the outside wall's were covered in dpc membrane, then battened on top, then rockwool insulatoin, then another dpc membrane on top stapled to the battern, then plaster board. Every thing was wet or damp 6 month's later.

All that work to insulate and to stop condensation , actually caused it, again the wall could not breath. You might want to try some air bricks, top and bottom, which might help.

 

[bobber]

Thanks for the input chaps, I have removed insulation, put back plasterboards and wall still sweating, any ideas how to remove bitumen paint?

 

[1john]

thinners may remove it. did you paint on brick or was there render / plaster, if so it may hack off?

 

[charly]

Thanks for the input chaps, I have removed insulation, put back plasterboards and wall still sweating, any ideas how to remove bitumen paint?

I tried everything to remove this from my outside stone walls the only thing that worked was sandblasting sorry

 

[bobber]

thinners may remove it. did you paint on brick or was there render / plaster, if so it may hack off?

painted on plaster, have scraped it all off

 

[dazdel]

Let us know if it solve's the problem. Cheer's.

 

[bobber]

Right, update chaps..........Scraped all that black c***p off walls, sliced kingspan down to 1" spaced toward the inner edge, keeping it off the outer wall, fitted vapour barrier, then refitted plasterboards (thank god I screwed them on in first place and not had wall plastered) and all seems to be ok so far . Thanks for the advice and input.....Rob

 

[thatbloke]

just to say if you ever need to remove any type of pain give strippers of sudbury a call

http://www.stripperspaintremovers.com/

they really know their stuff.

 

[bobber]

just to say if you ever need to remove any type of pain give strippers of sudbury a call

http://www.stripperspaintremovers.com/

they really know their stuff.

Tidy