Ventilation on Carport Roof

Yvonne in the UK asked:

Hi, hoping you can help me. I have a wooden enclosed carport with a rubber roof. We are going to insulate the roof between the rafters, and this will be classed as a cold roof. Insulation is 25mm Celotex and plasterboard underneath. There will be a 50mm air gap between the insulation and the underside of the roof. My question is, should I have ventilation or not? Thanks

Henry Staggs responded:

YES ... ventilation is important to prevent any potential moisture build up and all the yucky things that come with it.