roof ventilation.

2012paddy2012

Quote -The area at high level should be at least equal to continuous ventilation running the full length of the junction and 5 mm wide (see Diagram 12 (b)). Roofs with a pitch of less than - end quote-

My Roof Pitch is 12 degrees. It has tiles fitted with tech spec -to be fitted to roof of at least 17.5 pitch. It is causing a lot of problems. Will have to be replaced.
Its the ventilation issue that concerns me also , I see the timber batons under the tiles are wet.
I wonder is there sufficient ventilation , provided , as they are so wet.

The soffit has small ventilation holes every couple of feet running along the lower part of the roof , what does"15° and roofs of any pitch where the ceiling follows the pitch of the roof continuous ventilation running the full length of the eaves and 25 mm wide (see Diagram 12(c))." mean in ordinary language ....? see internal photo showing roof internal....

many thks
Paddy

DOCARCH

Do you know what type of roofing felt was used...breathable or not? Not ideal (and I personally would not rely on it) but if you use breathable roofing felt ususally you can 'get away' without other/soffit vents.

And, just a...Mod Note: I think you have started maybe 4 threads on your extension roof - appreciate your problems concerns - but can you keep all your queries to 1 thread please. No more threads on the matter. Thanks

2012paddy2012

DOCARCH wrote: »

Do you know what type of roofing felt was used...breathable or not? Not ideal (and I personally would not rely on it) but if you use breathable roofing felt ususally you can 'get away' without other/soffit vents.

And, just a...Mod Note: I think you have started maybe 4 threads on your extension roof - appreciate your problems concerns - but can you keep all your queries to 1 thread please. No more threads on the matter. Thanks

Thks sorry about that it is related but a different issue- you can delete if against rules

Drift

Hi OP,

It sounds from your post that there are soffit vents externally. Is this the case?

If so, and in the absence of breathable felt, these should be connected to an air gap above the insulation. Diagram 11 in Technical Guidance Document F will give you an idea of what you are looking for.

As DOCARCH says - in theory if the felt is breathable this may not be necessary.


As an aside: The Homebond "House Building Manual" used to have some great diagrams that explained various construction techniques. I'm not sure if the new version still does. It is quite expensive but a lot of your questions regarding details in the technical guidance documents might be explained by it. Have a look at it next time you're in Easons OP.

baby fish

2012paddy2012 wrote: »

Quote -
Its the ventilation issue that concerns me also , I see the timber batons under the tiles are wet.
I wonder is there sufficient ventilation , provided , as they are so wet.

They are wet because the pitch of the roof is under the minimum recommended 17.5 degree pitch, your pitch of 12 degrees is to low. Moisture in this area has nothing to do with ventilation in the soffit. The purpose of soffit ventilation is to ventilate the attic space, i.e the roof timbers under felt .