What does the foil do on insulation boards?
The Reason Why You Need Foil Insulation The radiant foil barrier reflects all that heat back into the air space between it and the roofing. When foil insulation is properly installed, the underside of the roof decking remains at or near the ambient temperature, even in full sun.
Which side of foil faced insulation faces out?
The reflective side of the board should be oriented to the exterior and the non- reflective white side should be oriented to the interior. EXCEPTION: If vinyl siding is to be installed over AP™ Foil- Faced sheathing, install foam boards with the white nonreflective side toward the vinyl siding.
Is foil faced foam board a vapor barrier?
Rigid foam board, especially foil-faced polyisocyanurate, creates a vapor-impermeable barrier, so the wall would have limited drying potential. Even more permeable types of insulation, such as expanded polystyrene, are vapor barriers when the installation is thick enough.

Does reflective foil insulation work?
Reflective insulation can block 95% of radiant heat and provides superior thermal performance. Reflective insulation reflects escaping heat back in the direction of your home’s interior. By harnessing the loss it lowers your heating bills.
Is silver foil insulation any good?
Foil is used in space-faring craft because of these great properties preventing radiant heat loss. Because space is a vacuum, there is very little heat lost by conduction, so foil is absolutely perfect.

Where do you put foil backed insulation?
Foil-faced insulation can use in a wide range for commercial and residential applications:
- Exterior wall,
- Roof,
- Ceiling applications (like in cathedral ceilings – frequently required for use in ceilings without attics)
Do you need Vapour barrier with foil backed insulation?
Using a vapour-check or foil backed plasterboard as a VCL Vapour control layers are always required whenever you insulate, irrespective of the insulation used.
Does reflective insulation keep cold out?
Works to keep warm air in during the winter and solar radiant heat out during the summer. Prevents up to 97% of solar radiation. Improves energy efficiency and lowers utility costs, especially if HVAC and duct systems are located in the attic.