Condensation in flat roof void

[Phillip Stephens]

Hello All, we had a loft conversion done about 9 years ago. I've recently noticed quite a bit of condensation on the underside of the roof void. The roof is part of a dormer and is a cold roof. It seems to happen only when its very cold. Removing the downlights while leaving all the windows (dormer + velux) open for a day or so and running a fan into the void seems to dry it out. I can feel the air movement when I reach into the void so I reckon the cold roof is working as it should but is struggling with the amount of moisture. I was hoping for some advice on how to prevent it happening and maybe a long term solution. We are not using the on-suite in the loft and are careful not to have anything that could increase moisture lying around.

 

[Wayners]

You need something like this.
What insulation is there?

 

[Phillip Stephens]

Thanks Wayners. I have a some photos from when the loft was constructed back in 2013/14. I think it was Kingspan that went it and there was at least a 120 mm gap to the OSB from the top of the insulation and there is a definite cold draught in the void which is expected in a cold roof. But I reckon it can't deal with the excess moisture in winter for some reason. Also there is no insulation in the downlight voids which could be making the issue worse. Is there I can retro seal the downlight voids without having to take the ceiling boards off completely? Thanks

 

[Wayners]

Somewhere on YouTube there is a guy covering this topic.
People getting condensation around and through where spotlights are. Also damp problems with incorrect ventilation.
Not my area although I've looked at the problems some have had.
Maybe you can get light insulated hood cover then pump some foam around. Just have to look for modern solutions.
I had similar loft conversion and decided on walls lights to avoid spots but thing's have moved on Vs 16 years ago when I did building works