Have a very old cape with an attic. In that attic there is currently some old batt on the floor that is seemingly doing nothing. In order to improve energy efficiency and to prepare for HVAC equipment to go up there, looking to make the attic a conditioned space.
My idea is to place rigid foam board up on the attic ceiling, in between the rafters, tape them together to prevent air flow, and then to spray foam (out of a can) the edges to fill in any remaining cracks.
1) The attic appears to have no ventilation (soffit, ridge vent, etc). Do I need to worry about this?
2) Do I need to put some foil backing up against the roof sheathing before the rigid foam board
3) How do I attach the rigid foam board to the roof sheathing
4) How do I attach one rigid foam board to another if I am stacking the rigid foam board to achieve my desired R-value
Any other considerations I should make?
I would be super grateful for any advice or direction on where to find answers.