How Radiant Barriers Help Cool Your Home
In addition to creating energy, solar technology involves controlling the heat that comes into your home. A radiant barrier is a sheet of thin material that looks like reinforced aluminum foil. You usually tack it up beneath your roof joists, and it keeps a lot of heat out of your attic.
The material itself isn't all that expensive at $0.20 per square foot. For a 2,000-square-foot house, the material costs $400. (Because your roof joists are angled, you need more material than the square footage of your house. Multiply your square footage by 1.25 to get a good approximation of how much you need. Don't worry if you don't cover the entire roof. Also, do not cover up any vents because radiant barriers will not transmit air.)
These barriers are advisable in hot climates because they cool down the house more than enough to pay you back in a few years. But if you want your attic to get warm in the winter, they may not be the best solution because they prevent heat from entering, resulting in a cooler house. Controlling the temperature in your attic is always a balance between seasonal extremes, so decide whether heat or cold is your major problem.
Installation is a bear, unless you can lay the material directly onto the floor (or over the joists and insulation the "floor" comprises). Open rafters are the best candidates, but if you have no floor and you have to hop around on joists, you may want to find a different solar investment.
When installing on overhead joists, absolutely get a very good stapler. Electric is best; get a powerful one. You're going to be holding your arms over your head half the time, and then you'll be crouching over and twisting into a pretzel shape the other half. When you pull the trigger, you want a good, solid staple to go in without argument.
Even if you can cover only a portion of the rafters, radiant barriers are worth it. Try to cover an entire medium-sized area rather than small spots at a number of different areas. The hottest spots on your roof (usually the southern exposures) are the best candidates.
Walls also work with radiant barriers, and doing a wall is usually a lot easier. An uninsulated garage that gets way too hot in the summer is a good candidate, although it may look like a spaceship when you're done.
Before you decide to spend the money and install a radiant barrier, go up into your attic and see what it's going to be like crawling around nailing it up. Envision lifting the material up into the attic and then unrolling it, cutting it, and holding it up into place. Envision the tools you need to carry around. One person can't put up radiant barriers, so get some assistance.
Attics can roast you fast. They can heat to over 130°F, easy. Working in the morning usually solves this problem, as does working in cooler months. Don't kid yourself; if the temperature feels really hot, it can be dangerous.