Damp in loft. Wet membrane or felt. Condensation or evidence of leak?

[GwayMan]

Hi all,

Property is 2003 semi-D that we purchased a couple of years ago. The first winter we were in I noticed condensation on the underside of the membrane in the loft. We added insulation, increased ventilation, and fitted all water tanks with lids and lagging jackets. Condensation has gone down a good bit but I still notice some damp patches on the membrane. At this point I'm not sure if it's condensation or possibly tell-tale signs of a roof leak from damaged tiles.

It seems pretty minor and there is enough ventilation for it to go away. At the moment it's lashing rain out with 96% humidity. I'm not sure if I need to possibly take another look at the tanks or if it could be out on the roof tiles.

[GALLERY=media, 105843]IMG_20210111_165023 by GwayMan posted 11 Jan 2021 at 7:34 PM[/GALLERY][GALLERY=media, 105842]IMG_20210111_164415 by GwayMan posted 11 Jan 2021 at 7:34 PM[/GALLERY]

 

[GwayMan]

I noticed the same pattern in two of the three different pitches of the roof, the back pitch just above water tank and along the side above the loft hatch. In some places there are just damp patches next to the timbers but in other places there seem to be bands of damp that stretch between timbers and have visible water droplets.

[GALLERY=media, 105844]IMG_20210111_165238 by GwayMan posted 11 Jan 2021 at 7:58 PM[/GALLERY]

 

[centralbelt]

Hello. I look to have the same issue in my loft, did you work out if it was a leak or condensation?

Thanks

 

[JohnD]

CONDENSATION IN LOFT (ANSWERS)

This seems to be the time of year for condensation in lofts, so instead of replying to lots of queries I though I would write this "one-size-fits-all" post. Please also see //www.diynot.com/wiki/Building%3ACondensation-in-Houses Condensation in lofts occurs when the amount of water...

www.diynot.com

 

[BlueLoo]

Do those tanks have venting?