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