Question
Should I include a radiant barrier in my new roof installation in Northern California?
I will replace wood shakes on an A-frame in Northern CA on the coast with standing seam metal and thought a radiant barrier under the metal might be a very effective first defense; raising the roof on 1x3 firring strips above the decking since the manufacturer says the barrier needs a small space to be effective. Radiant barrier would go on the decking, then firring strips, then roof. Is this a worthwhile investment? Any major cons? I installed a radiant barrier in my home below the joists of a flat roof in SoCal and find it VERY inexpensive, easy to install and VERY effective.
Answer
I love standing-seam metal roofs; they look great.
When assessing existing homes, the first priority in slowing down unconditioned attic air from entering the conditioned space is to create a thermal boundary at the floor of the attic:
- Air seal attic bypasses, chases, and penetrations;
- look at recessed lights and determine if they are ICAT-rated; and then
- insulate with blown in insulation to R-38.
Once these most effective measures are in place then adding a properly installed radiant barrier makes sense.
Radiant barriers need to be cleaned every now and then as dust will reduce the performance over time.
For more information:
Read "Is there a strong argument for using a bubble insulation or foil product on trusses instead of just a radiant barrier to reduce attic temps?", a Q&A answered by Danny Kelly.
