Breathable roofing membrane

[Clickem]

We live in a 1960's bungalow that was built on low lying, boggy land, so that we are in a fog/frost pocket that means the humidity in the house can be high. When the weather is very cold we get damp on the underside of the roof felt that wets the tops of the timbers, where they touch the felt, and can drip down onto the loft floor

We have improved the ventilation by vented bricks on the gable ends, vented roof tiles and vented sofit boards, but clearly still not enough. I think that the roof has been replaced at some time, as we seem to have 2 layers of roofing felt, the lower one is torn in places. We are thinking about a new roof and are asking if we should replace all the felt with breathable felt, and is it likely to help in solving the problem?

TIA

 

[Odds]

I have problems with damp and mould, and i'm considering a PIV unit to help improve the air flow around the house.
Perhaps that can help.
I'd certainly replace any roof felt with a breathable membrane. You have several options so look around before choosing.

 

[Clickem]

Sorry, I omitted to add that we fitted a PIV about 3 years ago. It does improve the loft ventilation, as it pulls air down which is replaced from outside. It also has improved the condensation on windows, turn the fan off and you can tell the difference next day. But along with all the other ventilation improvements we have made it has not completely solved the problem

 

[datarebal]

Post some pictures inside the loft and of the roof

 

[Clickem]

Images show the damp on the rafters and the two layers of felt. Please ask if any more images needed. TIA

 

[datarebal]

I see a non breathable felt type 1 f.
You say you have two layers ? Are seeing the second layer through the ripped areas ? They could just be poor repairs .
If the whole roof definately has two layers of felt, then there is no reason not to pull off the old .

 

[Clickem]

I see a non breathable felt type 1 f.
You say you have two layers ? Are seeing the second layer through the ripped areas ? They could just be poor repairs .
If the whole roof definately has two layers of felt, then there is no reason not to pull off the old .

Thanks, there are several areas where it is ripped, with another layer showing above, so I think two layers. Think that I may also try some circular push in soffit vents

 

[datarebal]

Two layers makes no sense . You could be seeing underlay repairs.
If it is definately two layers over the whole roof then it can only make things worse.I have resisted the usual insulation and extractor questions .. there's tons of top advice ref condensation on the site

 

[^woody^]

When the weather is very cold we get damp on the underside of the roof felt that wets the tops of the timbers,

There have been a few recent posts on this, and the answer is that in extremely cold weather condensation will always form on the underside of felt and even on breathable membrane.