Hi, I’m getting ready to have a new roof installed on our 44-year-old house. I’m considering having our roofer install radiant barrier OSB sheathing, but I have a couple of questions. I live in Pleasanton, California, between the San Francisco Bay and the Central Valley. We have quite a few 100-degree days each summer and would like to make our house more energy efficient. My first question is, is my climate a good place to have a radiant barrier? My second questions is, would the radiant barrier OSB be effective if it’s installed on top of the existing skip sheathing? We have two roofing companies bidding and one says that they remove the skip sheathing, which sounds correct to me, while the other says that they will leave the skip sheathing on?
The geographical area that you have described is in the United States Department of Energy’s climate zone 3. The continental U.S. Has seven climate zones, Climate zones 1-4 are deemed as ideal areas for deck applied attic radiant barriers and radiant barrier would be a good choice in your climate. DOE and Oakridge National Laboratories website has a radiant barrier calculator, answering a few simple questions and the calculator will give you a minimum dollar amount that you should expect to save on energy bills. A word of advice, when answering the question about duct work, all duct work leaks, so answering that questions as un-insulated duct work will give you a more realistic estimate on savings.
As for your second questions – applying the radiant barrier shiny side down into the attic with as little obstruction as possible, the radiant barrier is most efficient with a 24” air space, so removing the existing decking will allow for maximum efficiency of the radiant barrier. California has a Department of Consumer Affairs and that department has a list of approved radiant barrier manufactures. Also, RIMA’S website has a list of approved and verified radiant barrier manufacturers – using these references will ensure that you are purchasing a product that will perform to the manufacturer’s specifications and claims.