Damp and black mould behind 50 mm insulated plasterboard around window. Condensation or water ingress?

[ethan2019]

Hi everyone,


I’m looking for some advice from people with experience in damp diagnosis.


I removed some 50 mm insulated plasterboard from around one of my windows in the bedroom, after noticing damp around the window. The board was mechanically fixed directly to the wall with mushroom fixings.


When I removed it I found:


The concrete block wall behind was damp.
There was black mould on both the back of the insulated board and the block wall.
The left-hand side of the window is noticeably wetter than the right.
The right side is not as damp, but still has damp.
I haven’t yet removed the insulation above the window, so I don’t know the condition there, I only removed small section, but it looks dry.
There was no standing water or dripping, just damp masonry and mould.

Some additional details that may be important:


The foil facing on the insulated board was intact overall, but I cut it in a few places to run electrical cables.
There is one socket cut-out in the insulated board.
Around the outside of the window there was a gap between the frame and the render which I never sealed with silicone or another external sealant.
The house has hollow concrete block walls (Ireland).

I’m trying to determine whether this is most likely:

Condensation caused by warm air getting behind the insulation board.
Rainwater entering through the unsealed window perimeter.
A combination of both?

Before I reinstall the wall, I’d really like to identify the actual cause rather than just covering it up again.


I’ve attached photos of:
The exposed wall.
The removed insulation board.

Any opinions or suggestions on what to inspect next would be greatly appreciated.

 

[jj4091]

A pic of the outside would help, but I would tend to think this might bt your problem and the thing to do first.

"Rainwater entering through the unsealed window perimeter."

 

[^woody^]

Black mould is almost invariably related to internal humidity, so you need to consider whether that room, or the house generally is getting higher than normal humidity for various reasons - read the common condensation guides and check how you are dealing with the moisture you produce. That is a very common situation for mould between a cold wall and warm lining.

However to eliminate the very small bit not zero chance that the wall is not getting excess damp and evaporating it internally, you need to check the external wall and roof for issues. Penetrating damp would often be visible via stains, but not always. But evaporating moisture acts just like condensation, as it's trapped by the insulation, so is often confused with internally produced moisture/condensation.

 

[ethan2019]

thanks so much for your responses, unsealed window may have contributed letting small amount of water in, but it wasn't the reason for this I think. I do think now that its in fact condensation as mentioned by woody, coming from the kitchen that is just on the left , you can see it from added pictures. they share same wall. we never installed extractor fan above the cooker in kitchen and the door that is in the kitchen going out to the garden was never insulated or fitted properly, water was always dripping from the door in the winter, paint pealing all around the door, so condensation was bad in the kitchen, it must have entered that wall where the door is. the peace of insulation board was also missing there near the wall, so the vapor foil was not continues there. Woody mentioned roof, we have attic conversion and condensation was always an issue there, but the roof was fixed and attic insulated this year. but I think its not the attic because when we moved in 6 years ago and insulated that wall there was no issue with previous insulation when we took it down, so its something we done wrong with our install. I don't know if I should take down all the walls or not, they may be all the same behind, its just to much work I don't think I can handle any more of this, I am just exhausted after years of building
I think no point to take photos from the outside, window is now sealed with silicone, won't be leaking again if it ever was.