How-to for a cheap homemade radiant barrier for your attic. Radiant barriers battle the problem of emissivity in attics. When the sun beats down on the roof the shingles store energy then slowly gives that energy out in the form of radiant energy. So if you had a widget that could reflect that radiant energy away from the ceiling and back into the roof you could essentially reduce attic temperatures, therefore reducing your air conditioning load and save MONEY.
Step 1: Items and Tools
To make the radiant barrier you will need a small list of easy to find items. This list started me out and I made 240 square feet of radiant barrier. The limiting factor is the spray adhesive. The can says that it coveres 220sq.ft. but I was using double that rate. This made approximately ten 12'X2' (24sq.ft.) lengths.
1 Roll 36" X 33.3 yards painters Masking Paper (hardware store)
2 rolls of 12" X 75' generic aluminum foil (grocery store)
2 cans of 3M Super 77 spray adhesive (hardware store)
Staple gun w/staples
Step 2: Make the Radiant Barrier
This is easy. Roll the paper out into predetermined lengths. I used 12 ft because that is what my attic needed. Tape the starting end down with masking tape if you like. Spray the adhesive to the masking paper in a 2ft wide pattern. Then roll the aluminum foil out starting with the left roll and over lap 1/16th" with the second roll. When you reach the desired length cut the now finished radiant barrier, leave the excess 1 ft until installation. I then used a broom to clean and press the foil to the paper.
Step 3: Install the Radiant Barrier
Installation kindof sucks if your attic is tight or installation is during the heat of a summer day. MAKE SURE FOIL FACES ROOF! My method was start at the top leaving at least 18 inches of space. Then staple my way down starting with the side that does not contain the excess paper. I stapled at about 6in intervals. After both sides are stapled you can then remove the excess with a razor blade.
Step 4: Conclusion
I have not done any baseline and/or final testing, like a good engineer would, but I do that at work. I know this will work because of the great reflective properties of aluminum with an air gap. The air gap is the real reason for attaching to the rafters. There are two other ways to add an after construction radiant barrier, spray on and attic floor. Those two methods are not as good as the rafter method because spray on has no air gap and the attic floor barrier collects dust. The best barrier is the roof designed with reflectiveness built in, but most people don't think of that or want the cost associated with it. By the way a radiant barrier may not be well suited for your climate, I would perform research before committing the time and energy to installing one. Well this ends my first Instructable and hope it was useful.