In article
,
RobertL writes
On Apr 3, 1:14*am, Tim S wrote:
OK...

A poser:

As I understand it, sarking is for windproofing, not water proofing a tiled
roof?

Then, if we install celotex between and under the rafters and therefore
become concerned that we maintain good ventilation above the celotex, then
why not just remove the sarking and let the roof breath through the tiling?
The celotex (at al) will give us our wind proofing...


i put in a BC application to add celotex under an existing slate
roof. i proposed slate/waterproof_sarking /50mm_airgap/celotex/
thinsulex/plasterboard. the BCO commented that if I used a breathable
membrane instead of waterproof sarking then I only needed a 10mm
airgap.

10mm, interesting to know, thank you.

Watch out using breathable membranes over boarded roofs, they don't like
getting scuffed and will leak if they do.

Btw, I'd say skip the thinsulex and save some cash.
--
fred
BBC3, ITV2/3/4, channels going to the DOGs