Photo Courtesy of commons.wikimedia.orgRadiant heat travels through air, therefore in order for a radiant barrier to be effective you need to have air space on at least one side of the barrier. This is one of the most important concepts when installing a radiant barrier, regardless of the application. The worst thing you could do is sandwich the barrier between two products such as roof sheeting and shingles, or drywall and foam insulation.If you are installing radiant barrier on the rafters in your attic you will already have two airspaces: one between the barrier and the sheeting and the other is the air inside the attic. If you are installing radiant barrier under your radiant heated floor you will have the air above the foil. When installing a radiant barrier in walls you can either recess the barrier into the stud cavity or roll it across the studs and attach furring strips or strapping prior to hanging drywall. When installing radiant heated floors all you need to do is install the radiant barrier a few inches below the tubing and you will have an air gap above and below the foil. Are you starting to see a pattern?Hopefully I have cleared up some of the mystery surrounding radiant barriers. So when you are planning your DIY radiant barrier project just remember to include an air gap on at least one side of the barrier. It is as simple as that, and now you know how to install radiant barrier in any application.