warm roof rafters

Hi all, Looking for experience of anyone converting a house cold pitched roof to warm roof. Can't find much info online about anyone converting an existent roof from cold to warm & roofing companies not really advertising this as a service. It would seem to me if you were having your roof...

Nearly completed our timber-framed garden office/gym using 2x4 studs with a warm roof. About to start insulating the internal walls now; the plan was to fit a vpc sheet over the insulated stud walls and then plaster-board over this and under the rafters (without a vpc). However, my son quite...