I've had soffit ventilators for 25 years, and recently tripled insulation in the loft and fitted refurb rafter ventilators to ensure air had free passage from soffits. I've roof felt rather than permiable membrane but although I've had no sign of obvious condensation, I'd thought of fitting vent tiles near to ridge. BUT someone said 'no need' just wedge a bit of polystyrene between overlapping layers of roofing felt, and that gives adequate ventilation.
Questions: Does that work? What stops wasps entering loft to make a nest?
Jim Chisholm