Broadback wrote:
Recently I have had loft insulation installed, the "surveyor" maintained
that even though there was no obvious form of ventilation it was not
needed because the roof felt was a breathable membrane, looks like
ordinary roof felt to me.
Anyway 2 questions, when is the best time to check for condensation, in
warm damp weather, cold, or when?
Second if I need ventilation I intend to put through air bricks at
either end of the gables, does it matter how high they are placed?
TIA

1/. Condensation will most likley occur on still cold days when hot
steamy air from the bedroom ;-) gets into the loft and condenses on
anything below dew point.

2/. Beware of end gable vents...they do little for rafter ends in the
eave area..the normal recommendation is to vent the eaves, because they
are likely the coldest place, and the ridge, because this is the
warmest. Then a slow convection can draw air from outside into the eaves
and up through the ridge.