Things You'll Need
Mylar reflective insulation is comprised of polyester and aluminum, resulting in a silver-colored radiant barrier that reflects radiant heat. It keeps your home cooler in the summer and warmer in winter. This type of insulation is commonly used to insulate roofs and attics. Mylar insulation reflects 97 percent of radiant heat in the home, potentially cutting home energy costs significantly. Mylar insulation is so effective, that NASA uses it to shield the International Space Station against the thermal radiation of the sun and the bitter cold of space. Mylar insulation is available in different weights. Heavier weight equals better performance.
Warm/Hot Climate Installation
Measure the horizontal length of your attic rafters. Add 1 foot of length to the measurement. Measure and mark the roll of insulation at both sides of the sheet, according to your final measurement.
Using a straight edge, draw a line between the two marks. Cut along the line with scissors.
Lay the sheet horizontally, working left to right. Start at the bottom of the rafters.
Staple the Mylar sheet to the bottom of all rafters. Place the staples about 3 inches apart.
Repeat steps 1 to 4 until you reach the peak. Leave a 3- to 5-inch gap between the top sheet of Mylar and the ridge to retain proper air flow.
Repeat steps 1 to 5 on the opposite side of the roof.
For gable roofs, apply Mylar horizontally to the framing, using steps 1 to 5. You do not have to leave a gap at the top of the gable wall.
Cold/Mixed Climate Installation
Measure the length of your attic floor. Measure and cut pieces of sheeting to match.
Starting in a far corner, roll out the sheeting. Lay it loosely on top of existing insulation for proper air flow.
Lay another sheet of insulation next to the previous one, overlapping the sheets about 1 to 2 inches.
Use small pieces of foil tape to join the pieces at 1-foot intervals.
Cut the foil to fit around obstacles such as bracing or supports. Cut a slit in the foil, place it around the obstacle, and tape it back together. Continue steps 2 to 5 until the attic floor is completely covered. Make sure there are no gaps.
Installing Mylar over attic floor insulation is a snap if you measure your attic, then cut the sheets and tape them together in a large, open space, like your driveway. Tape sheets together to make 8- to 12-foot sections to quickly cover large spaces. When installing Mylar on rafters, fold the cut pieces together loosely, matching the ends. Roll the sheet. If you have a partner, you can each grab one end and pull it out, preventing folds or wrinkles from forming in the sheeting.
It is not recommended to use radiant barrier insulation alone in colder climates. Check local regulations for standard insulation guidelines, and apply the Mylar insulation on top of recommended standard insulation.