Loft Ventilation and condensation

[akist]

This is a summary of my issue in as few words as possible and many details ommitted.

I have made a mistake on my roof: the roofers fixed the breathable membrane over the main ridge. Their reasoning was to make the house completely water proof without (and until) the roof tiles, which were fitted weeks later.

The hot(er) air cannot escape from the top ridge. I am having a lot of condensation. I have plenty of eaves vents and there is a path for air to go from one side of the roof to the other, from eave to eave. But as hot(er) air rises and the ridge is at the top, that is where the humid air stays, condenses and runs down on the underside of the "breathable" membrane.

The only way I can imagine to fix this is by removing the ridge tiles, lifting up the dry ridge lining and cutting open the membrane (tyvec) to let hot air escape and vent.

Am I the only house that does not vent at the ridge? Could there be an alternative way?

 

[JohnD]

Where is the water coming from? Do you have holes in your ceilings, e.g. for downlighters? Does the loft hatch fit? Does your bathroom extractor fan work properly? Do you have damp new plaster or brickwork? Do you drape wet washing inside your home?

 

[SpecialK]

Can you cut the felt from the inside?

 

[akist]

No, I cannot as there is a huge steel beam forming the ridge. My plan is to get a roofer or the handyman to climb up there, remove the ridge tiles (dry ridge system, all they need is a screwdriver), lift up the dry ridge membrane, and cut the felt, then put everything back on.

But I was trying to avoid doing this if there were another method...

 

[JohnD]

You say you have good eaves ventilation. So your problem is excessive water vapour.

Where is it coming from?

You need to rectify the source of water.

 

[robinbanks]

lift up the dry ridge membrane

Let's hope it's not become too well adhered to the roof in the time it's been fitted..

Prop the felt open at an overlap first and see if it helps?

 

[akist]

Prop the felt open at an overlap first and see if it helps?

Very good point, if I can find the overlap from the inside! I probably can. It will not be right at the top but it would be close to the top.