the entire roof no but one spot maybe... but hell i see houses with no snow on one spot of the roof and i have never said ooh their growing marijuana. i think your friend needs to lay off the strains that causes paranoia if that doesn't work try insulating the roof better. be careful and make sure you know what your doing you cant just throw insulation in your rafters the hot and cold meet and cause condensation and rots your roof away you need good air flow between the roof and insulation good look man. spray foam insulation the closed cell works the best you will not have to worry about anything but heat issue that shits unreal!!! very expensive though.