Ready to dig into the trade-offs? Here we go.
#1 – No Ductwork in the Attic. If this is the case the home is Title 24 Part 6 compliant and they can use any roof they prefer.
This strengthens my theory that the primary function of Title 24 Part 6 as it pertains to re-roofing is to take pressure off of the electric grid in the summertime, because a cool roof will only cool the attic which will make the AC unit a bit more efficient which will take some pressure off of the grid during periods of peak usage, however if there is no AC Unit with ductwork in the attic there can be no help to the grid therefore no reason to install a cool roof.
#2 – Existing ducts in the attic are insulated and sealed according to §151(f)10.
#3 – Insulation with a thermal resistance of at least 0.85 hr ft or at least a ¾ inch air space is added to the roof deck over an attic.
#4 - Radiant Barrier OSB. Building has radiant barrier in the attic meeting the requirements of §151(f)2. This one can get roofing contractors into some trouble because of how radiant barrier is to be properly installed. When you install radiant barrier OSB on a shake tear off you are supposed to remove every piece of skip sheathing prior to installation. This is something the radiant barrier industry has not talked much about with roofing contractors and many roofing contractors I have talked to were completely taken by surprise by this. LP TechShield used to have very clear install instructions for this on their site. I am very disappointed to see that they have removed any mention of how to install over skip sheeting from their web site (as of 2-10-10). I still have a copy of the old LP TechShield install instructions that clearly show and explain that skip sheathing is to be removed and that if that is not possible you should remove every other piece and that this would reduce the effectiveness of the material by at least 30%. Now their install instructions just make reference to maintaining a ¾ inch airspace under the material (ie. Don’t install over skip sheathing).
The more I research this the more upset I am getting. All of the radiant barrier companies are showing installs on new construction and are deliberately leaving out how to properly deal with installs on roofs with skip sheathing. I really feel this is wrong and misleading.
Here is a city that has it together and there is great information on radiant barrier installation here (go to page 5): http://www.roseville.ca.us/civica/filebank/blobdload.asp?BlobID=16444
Here is another explanation of why it will not work when installed over skip sheathing:
Also you should note that when radiant barrier of any kind is used ventilation becomes extremely important. Here is a good resource:
Another important point is that as of right now (2-10-10) it does not appear that radiant barrier will qualify for the federal tax credit. See link below for more information.
#5 – Double the Ventilation. In climate zones 10, 12 and 13, with 1 ft2 of free ventilation area of attic ventilation for every 150 ft2 of attic floor area, and where at least 30 percent of the free ventilation area is within 2 feet vertical distance of the roof ridge.
Roof ventilation is so important and this trade off really validates the effectiveness and importance of adequate and balanced ventilation. For more information check this site out:
#6 – Minimum R-30 Insulation in the Attic. This is my favorite trade-off. I live in a climate zone in California that is required to comply with Title 24 Part 6. My WINTER electric bills are about 3x as high as my summertime bills. If I were to install a cool roof or one of the other trade offs, they would help me a little in the Summer but would do nothing to help me with my bills in the Winter. Who is the real winner in that? PG&E if you ask me. I want the option that will both make my home more comfortable and energy efficient all year long. Just my opinion…
How should this influence roofing marketing? It would be good to advertise that you are well versed in the trade-offs and that you would be happy to provide a complimentary “Title 24 Part 6 Compliance Evaluation” in which you would make your recommendation for which option is best, regardless of the roofing contractor they choose. This is your chance to be the expert and really stand out from your competition.
Please let me know what is your favorite option for compliance with Title 24 Part 6. Have fun!