On 15/03/16 15:09, The Natural Philosopher wrote:
On 15/03/16 14:55, Tim Watts wrote:
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?


Cold air isn't moist enough to condense of rafters that are no colder
than it is.

What about 'condensation requires warm moist are to come into contact
with *colder* surfaces' do you fail to get?

See my other post shed.


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


BCOs don't have degrees in engineering by and large.

Worthy souls though they are.



Now let me see. Listen to the BCO with his knowledge of the regs and
years of experience in this field - or someone on the internet?