2019 Idaho Real Estate Blog

Cool that attic Main The Durable Green Home
Radiant barriers do they work?.....

I have used several radiant barriers in the  last couple  years, one of  these made by Sherman Williams paint is a low emissivity coating (paint) that is applied  to the underside of  roof decks in the attic to lower radiant heat gain to the attic  by basically reflecting it. The results are  they work. a very good  article  was in the Environmental building news recent issue volume 17 www.buildinggreen.com in my own attic I tested the radiant paint a year or  so ago and found that the same exposure, same roofing, by applying  the paint it reduced the attic temperature 10 degrees. Tech shield is a OSB sheathing product with foil  on one side and the claims of the manufacturer state 30 degree attic temperature reductions, while i have not used this product yet, I do know  that in Warmer (Arizona, Nevada, California) builders are using the product in mass quantities. If  anyone has used these please  comment!

Also Tyvek has a product out called  Attic  wrap. Chuck Miller  of  Chuck  Miller construction has  used  this  in some of his  buildings and it  might be  worth a call to ask him how  they did. 229-2553. I do know it took some rethinking on the  framers part because this is applied to the rafters or  trusses before sheathing the roof on new  construction. The product  is  applied  as a installer  goes up the roof over the rafters, then a plastic cap is fastened over the top  of the rafter causing the wrap to become tight and create  the 1 1/2 inch air space  that a radiant barrier really needs, it also adheres to  the previous layer creating a bulk water barrier, but  is over 20 perms allowing  moisture to escape the attic  and allowing it to  travel  up  the air space out the ridge vent ( ridge  vents are the only vents that I think work) This  is a great way to build a cold roof without  all the extra framing and sheathing!!!

Now do they work? yes they do. BUT, proper  ventilation can reduce the attic far more than radiant barriers. In my own attic, the attic with radiant barrier has poor ventilation ( attic over shop) and the main roof  attic has  continuous  ridge (air vent-certianteed) and continuous soffit vents. the properly vented attic is 30 degrees cooler  on the same day than the attic  with the radiant barrier even after the 10 degree drop in attic temperature after we applied the radiant barrier. combine both  and a person could significantly reduce  attic temperatures. COOL STUFF-really it is COOLER

 
Posted by Tad Duby at 3/15/2008 12:03:00 AM
Comments (2)
Re:Cool that attic
hey, Tad- thanks for the article on the oft-overlooked world of attics! I've been looking into and testing Sherwin's E-Barrier paint starting last year, and the performance results are impressive. It seems to also have a decent cost/benefit ratio. I'll soon be starting my first whole house using the E-Barrier, and I'm excited to follow its performance through the blistering months of summer! Thanks again for your blog info- Kevin Chandler
Posted by on 4/15/2008 1:03 PM
Re:Cool that attic
thanks Kevin, I would welcome the results. my ownt test showed about a 10 degree temperature drop in the attic in the summer. Good ventilation did far more for temperature drop, but both would be highly effective. look foward to the results.
Posted by on 4/15/2008 4:44 PM
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