Alternatively use two half sheets of 3 4 inch.
How to insulate a roof and soffit.
In most residential homes the soffit and associated vents is the structural part of the roof that hangs over the side of the home.
Construct a soffit or eaves overhang combined with assuring that an opening is provided all along the top of the building wall by removing any blocking between roof rafters at the top plate combined with use of roof insulation baffles to assure an air inflow pathway under the roof deck.
How to keep blow in insulation out of soffits.
Lay strips of 3 4 inch plywood that are at least 24 inches wide across the floor of the attic.
You need one baffle for each.
If the attic is insulated with fiberglass batts just pull back any that are blocking the flow of air.
The principle behind soffits is to allow air to circulate in and around the attic.
Insulating and venting when there is no roof soffit.
Set the baffles inside the attic opening along with a loaded staple gun.
The soffit vents are now installed but you still need to make sure there s no insulation blocking the new vents.
If there s blown in insulation like ours rake back the fluffy stuff with a 3 or 4 ft long 1 x 6 or use a garden rake or hoe.
To insulate the roof itself you either use spray foam or retrofit with it with rigid foam board.
For the same reason insulation shouldn t touch the roof s underside.