Frozen membrane in new roof - is this normal?

[Crafty424]

Last month I had a reroof done on my 1970s house all done to building regs standards by a NFRC company including added loft insulation. I was in the loft space earlier this week and I noticed the new breathable membrane was all covered in frost. I phoned my roofing contractor and he suggested it was normal in these temperatures we’re currently experiencing in the UK. Is this right? I’m very concerned about the amount of moisture on the underside of the membrane. Previously when I checked the membrane looked bone dry.

What can I do to resolve this issue if it is a problem. The loft hatch could do with a draft excluder putting around it. I don’t have anything else letting moisture into the loft space like extractor fans. Thanks.

 

[JohnD]

Freezing is normal. The amount of condensation might not be. I can't see it, it looks like frost not ice.

See

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

 

[Crafty424]

Yes, it’s definitely frost not ice. The new insulation has made the rooms below warmer and the loft colder. I can feel airflow when I put my head in the loft. I’m just concerned about what’s going to happen when the frost thaws as there’s quite a lot up there especially near eaves. I’ve never noticed frost with the old roof but then I don’t think I ever looked inside during such a cold snap.

 

[JohnD]

It will tend to trickle down the felt. I think you have breathable membrane so some of the vapour will escape through it. It will melt first on the sunny side.

Usually, there are gaps at the eaves. In my house you can see daylight. Check it is not blocked by insulation. You can get ventilation shields to give a passage for air.