As I have probably mentioned before I have a 40m2 timber framed garage in which I am creating a 4.8m X 2.3m Mancave at the back end. The floor, outer walls, dividing wall and ceiling have all been insulated with 75mm PU insulation. With me only getting the power installed now, previously the room has been unheated but these last few days have been a real test of the insulation. Despite outside temperatures in the high twenties and the uninsulated part of the garage getting quite hot the mancave has remained remarkably cool. So if it is not letting heat in it bodes well for keeping heat in now that I will be able to heat it, success!
Richard