AndyW9999

I have 20mm polystyrene sheet to insulate the interior of the roof (the polystyrene is appropriate to this use, relevant BS EN standards - the 'outbuilding' is my new posh shed not a dwelling of any kind ? The roof (sloping not flat) is constructed of 20mm OSB on wood joists (photo) and covered with heavy duty bituminous felt externally. I'm thinking of applying the polystyrene direct to the underside of the OSB using a spray adhesive. Is it ok to do this?...Im wondering if there could be any issues with the OSB being 'sealed' both sides? Thanks Andy https://photos.app.goo.gl/hR3GJWvXyNuwqsVJ6