On 15/03/16 13:47, The Natural Philosopher wrote:
On 15/03/16 13:33, Tim Watts wrote:
Necessary unless you have breathable membrane. Otherwise the air cannot
circulate and is trapped (with breathable membrane it is sufficient that
moisture diffuses through the membrane and out between tile joints.

The point being that with celotex in, there wont BE any warm moist air.
Any rain will run down towards the eaves vents.



And the cold moist air?

Your advice seems to be at odds with my discussions with the BCO.