Rigid foam is the optimal choice for an attic.
Skylight insulation attic.
Inspect the existing skylight for signs of water leakage such as water stains and rot.
Learn how to insulate a skylight shaft here.
Unsealed attics are often insulated along the attic floor with blown fiberglass or cellulose insulation.
These range in price from 150 500 for a 2 x 4 ft sized skylight.
A finished attic should be insulated much like the rest of the house with insulation in the walls and ceiling.
That means insulating the attic floor only not the walls and having vents in the roof.
How to insulate and air seal skylight shaft walls.
If a skylight is installed in the roof over an attic a shaft must be built to connect the skylight with the ceiling underneath.
Set aside existing attic floor insulation to expose the framing at the base of the skylight shaft to be air sealed.
Because the shaft walls separate the interior of the house from an unconditioned attic it s essential that they be well insulated.
With a finished attic insulation must help keep the attic areas comfortable.
A different type of insulation will need to be installed along the skylight shaft walls one that will maintain both the full alignment or contact with the back side of the sheathing for the height of the skylight shaft walls and at least.
If a skylight shaft contains an air permeable insulation such as cellulose or fiberglass the insulation should be enclosed on the attic side to create an air barrier.
How to insulate a finished attic.
Repair skylight flashing from the roof exterior and replace any damaged framing as necessary.
Skylights are now sold as kits that usually include the necessary flashing materials as well.