Advice on installing wood outbuilding roof insulation Questions answered and a range of solutions on problems and issues encountered with timber framed buildings

[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 glue.
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

[B4Less]

You could potentially do this although the adhesive would need to be suitable to bond EPS to OSB. 20mm os EPS isn't going to offer much in the way of thermal performance, a foil-faced PIR insulation board would be better. They're approximately 40% more thermally efficient than EPS. EPS is useful where space isn't at a premium.