If I am using vapour permeable underlays (VPU’s), do I need any further ventilation?
In the vast majority of cases, Yes!… This is because air movement through the tiles or slates cannot be relied upon for the life of the roof. All ‘Cold Roofs’ need some additional ventilation (whether it be eave or ridge or a combination of both). Most ‘Warm Roofs’ need some additional ventilation (unless built specifically for a ‘simple’ roof, and to a high integrity with VPU’s and well-sealed ceilings).
