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...

Patches of my sarking are falling off and I see no evidence of water ingress
in those areas, but I do feel the air moving when the wind blows.

Just a thought...

Tim

The saking, underlay, felting or breather membrane, call it what you
like is soley a vapour barrier. Covering wind driven snow and frost
condensation. It will cut down on wind ingress but not totally unless
all horizontal and vertical joints are taped.

An air gap is important as it keeps the gap between insulation and
roof covering aired to stop mildew growth.