Dampness perhaps related to building construction / materials

[Paul205]

Dear All,

I own a detatched property which suffers from dampness / light mould in the plasterboard that surrounds both windows in one room. The windows are west facing.

The dampness appears to perhaps start on the horizontal plasterboard that sits above the windows and then passes down the vertical plasterboard to the side of the windows where it gets progressively worse where the vertical plasterboard meets the internal window boards.

The dampness is sufficient enough to make fresh paint fall off at the window board after around 1 year of paint application.

The property has outer brick with a cavity and then internal grey block. The dampness seems to be at its worst right against the windows ie appears to be trickling down the inside of the outer brick.

The dampness seems to have been in place for circa 15 years. A boiler was fitted in the loft around 5 years ago so this does not seem to have contributed. The internal side of the internal block in the loft shows no damp at all.

A previous owner appears to have applied some silicon or similar material to the outer brick around 5 coarses above one of the windows. I cannot see any cracking in the external brick.

I have attached a photo of the house from the outside.

Thoughts on what could be causing this would be appreciated.

Cheers




Paul

 

[Paul205]

I am thinking that this moisutre

maybe caused by unfilled joints in the grey looking material that projects outwards from the house (ie at 90 degrees to the facia) or perhaps the gap that seems to be between the same material and the mortar at the roof apex. Please see more photos. I have circled the areas I think may have caused the moisture in red.

 

[tony1851]

Two possibilites;

Either driving rain against the window reveals (wet-facing) through not being properly sealed,
or possibly cold-bridging causing condensation.

(unlikely to be anything to do with the gaps in the undercloak just below the tiles).

 

[Paul205]

Thanks Tony, the windows are in good shape, do you mean they could be poorly sealed against the brick on the outside