There are two basic methods for installing attic radiant barrier: one for protecting your home from the heat outside, and the other for keeping the heat inside your home. There are many areas in the country where you may choose to use both. If your climate experiences both extreme cold and heat you will benefit from energy savings all year round.
With either method, be sure that you use perforated radiant barrier. Before you install your radiant barrier foil you need to eliminate any air leaks. Two common culprits are can light fixtures and attic doors. You do not, however, want to seal up any vents that aid in the air flow design of the attic. This is also a good time to make sure that your existing attic insulation is still sufficient to meet your local codes. When installing the foil, it is easiest to start in the corners and work towards the middle, and don’t forget to install radiant barrier on the gable ends and knee walls.
If your primary reason for installing radiant foil in your attic is to cool your house, you will want to install the radiant barrier on the rafters of your attic. With this method, you prevent the hot sun from heating up the entire attic space. This is especially beneficial if you have any HVAC ductwork or equipment in your attic. If there are air ducts in your attic, be sure to protect them with radiant barrier insulation.
When you are installing your attic radiant barrier it is important that you leave 6” of space at the bottom and top of the rafters. Another important thing to mention is that you need to cut openings in the radiant barrier foil to accommodate any vents or fans. It is crucial that the air is allowed to flow through the attic as though the radiant barrier isn’t even there. These small gaps in coverage will not be significant enough to hinder the performance of your radiant barrier in attic.
Another option for installing a radiant barrier in an attic is to place it on the attic floor, on top of the existing insulation. This method is suggested if you are in a cold climate and want to reflect the home’s heat back into the living space where it belongs. Take care when installing your radiant barrier to leave a small gap between the sheets. Do not overlap and do not tape the seams. Again, you want the air to flow freely as though there was no barrier at all.
Installing a radiant barrier in your attic is a simple and inexpensive way to lower your energy footprint and make your home more comfortable.