Remodeling Tips and Reviews

Installing Radiant Barrier in your Walls and Attic

Installing Radiant Barrier in your Walls and Attic

Feb 21, 2012

Adding Radiant Barrier in your attic or walls can make a large difference in your utilities bills over time. Radiant heat is heat that results from hot surfaces radiating heat off of them and warming the space around them. Think of that electric stove top when it is one and you can feel the heat several inches about the element. Your home is heated the same way by the sun. As the sun heats up your roof, your attic becomes hot ( upwards of 140 degrees in Summer) and eventually that heat works its way into your home causing your A/C to run and driving up your electric bill. By installing radiant barrier you significantly slow the heat transfer down with the use of Aluminum. Think about that baked potato you wrap in aluminum. You do it so the outside of the potato is not charred black after an hour of cooking in the oven at 500 degrees. The aluminum slows down the transfer of heat significantly.

I’m not a fan of buying radiant paint and spraying it under the rafters, for the cost and installation, it simply is not nearly as effective as radiant foil. Foil reflects around 95% of heat versus 75% best case for the radiant paint. Installing foil is an easy process and only requires staples and aluminum tape to create the ideal attic space. To install it I recommend buying 4′ rolls of radiant barrier which will straddle 16″ and 24″ spacing on rafters. Starting at the bottom of the rafters I simply cut a piece to length and staple it on all rafters as I move up leaving a space at the top for hot air to excape. Once the radiant barrier is up I tape the seams with Aluminum Tape. The result is a dramatically cooler space. To figure out the square footage you need I would suggest taking the square footage of your house and multiply it by:

  • Not Steep: Under 5/12 roof pitch which is easy to walk on – Probably under 8’ at the highest point for most homes Multiple by 1.2-1.3x
  • Moderately Steep: 6/12 – 8/12 slightly difficult to walk up. Ridge usually over 8” high, Multiply 1.3-1.4x
  • Very Steep: 10/12 or higher difficult or impossible to walk up considered a very “high pitch” or “church style” roof multiply by 1.4-1.5x

I installed radiant foil in my house several years ago and noticed a 20%+ drop in my Summer cooling bill. I live in Texas and we know heat. So the radiant barrier easily paid for itself in a few years.