In message , Jim K
writes
Tim Lamb Wrote in message:
In message , Jim K
writes
Tim Lamb Wrote in message:
In message , David
writes
Further into the clear out I've found some of those circular white plastic
eaves vents which allow air to circulate up the rafters, over the top and
down the other side. Hole saw as well.

Intended, I think, for boarded over loft ceilings where there is a risk of
condensation next to the roof.

Looking around, nobody seems to have them in this row of houses.

Are they still considered to be a good idea?

Hmm.. builders seem to have latched on to the idea that porous roofing
membrane makes eaves ventilation redundant.

Building Control don't have the same view here! They insisted on a
significant gap between the membrane and any loft insulation.


Flat roof?

No. Conventional pitched rafters but *included attic* (chalet bungalow).


So no loft as such for "loft insulation" to go in? Presumably you
meant kingspan or similar sheet insulation?

I've used both. BC didn't like 200mm of Rockwool between the rafters
because he felt it impacted on the space for ventilation. I changed to
100mm PIR foam between and 35mm foam/plasterboard sandwich underneath.

The small attic spaces have 100mm PIR between floor joists and 100mm
Rockwool over all.

--
Tim Lamb