The first is stapling foil to the bottom of the roof rafters the second is laying it out over the existing attic ceiling insulation.
How to install foil roof insulation.
To install foil insulation roll it out parallel to the ridge and cut it with a utility knife starting at the drip edge and working your way up.
After you are done cut to adjust the length and get ready to work the next layer.
Foil insulation installation in an existing attic you can either staple rolls of foil radiant barrier insulation to the rafters or lay the foil out on top of the insulation.
When installing foil insulation you must use a quality stapler.
Overlap seams by about 3 inches.
Attaching radiant barrier insulation to the rafters is the most effective method to employ but both methods have their advantages and disadvantages.
Use a stick 1 4 furring strip with nail in the end works well to help push the barrier into the tight spaces of your attic.
Install it vertically be sure to start from a high point and roll the insulation down.
Starting at one end of your attic install our ultima foil breathable radiant barrier across attic floor joists plywood decking or existing insulation.
The process is more tricky than installing foil insulation during the construction of a property but can be undertaken if need be.
Attach it to the purloins with double stick tape to hold it in place until you.
If there is already insulation between the joists increase the r value by installing unfaced roll insulation right on top.
Reflective foil insulation installation on a roof is usually done in the ceiling attics or other spaces that separate the roof from the ceiling.
Remember to apply a decent amount of tension when stapling and to do it at 50 to 100 mm intervals.
Run the unfaced strips perpendicular to the joists and butt each strip tightly together to form an airtight blanket of insulation.