Here in Tucson, AZ we have a lot of ducts on the rooftop. This is because many older homes are flat roofs and only had swamp coolers when they were built. This leaves no other place but the roof to install ducts for AC. Many of these ducts were never insulated. Many homeowners do not want to replace whole duct systems just to insulate on the inside of the duct - for obvious cost reasons. They always call us as an insulator to take care of this and we have always passed on it.
Recently I suggested that we start using closed cell spray foam to insulate these ducts, but we must protect them from the searing desert sun. My plan is to find out the best roof coating that I can use to cover the spray foam and have a solution for all these homeowners.
1) Do you see any potential problems with this solution?
2) Any recommendations for roof coatings?
Jason - Do you recommend this because that is how foam roofs are done? I am not sure the primer would be necessary in this application as we are not adhering to a roof system, but a duct system which is being encased. Since we are creating a monolithic encased structure, I do not believe strict adhesion to the ducts is important like it may be in the roofing system. Water intrusion of the duct system will be addressed prior to insulating by sealing with mastic.
Hi Craig. It was no glitch. One requirement of coatings is to report annual sales. Or head office failed to do that so the star was removed. There is also a new requirement that emissivity be checked at the three year mark, just as the reflectivity has always had that requirement. Our corporate office also failed to do that/
We are in the process of getting it back but it might take three years. I cannot defend the corporate office on this.
On the products behalf., I will say this;
Many years ago Cerama-Tech's Emmisivity was certified by the Florida Solar Enrgy Center at TE = .90
A few years later we were certified by Surface Optics Corp to have solar reflectivity at SR = .83 and .788 at three years.
In 2010 a white paper study was conducted by Oak Ridge Nationa; Laboratory.Building Envelopes Research Department
Part of that study showed our SR = .812 and TE = .85.
In 2012 test were conducted on Cerama-Tech at Lawrence Berkeley National Laboratory. One of the tests showed TE = .93.
None of these tests will get our energy star back. However, I know of no more prestigious scientists and energy laboratories to prove our products consistency in perfornance over 20+ years.
I have bben applying our coating to rooftop ac units and ducts for over 25 years. I was doing that years before there even was an Energy Star, all ir requires is a 4 foot piece of ac duct and a warm day. If they feel the difference, the job is sold and they dont care about the energy star,.
This is a nosy new yorker pitching in.
I was in Vegas recently and riding the monorail you can see all kinds of ductwork on roofs with foam sprayed on it and covered with various roof coatings. The coatings seem to be picked to match the roof coating. Your idea will work fine in Tucson. But do call SPFA and ask for some guidance. It may be a better choice to use some sort of slip sheet to cover duct joints before you spray it so any thermal expansion/contraction doesn't crack the foam. SPFA has technical data sheets available on their website too. www.sprayfoam.org
A big problem for foam roofs is any holes in the foam tend to pierce the coatings and eventually they pool water. In Tucson, that may not be a rain problem, but it could be a condensation problem. Spraying down on a flat surface, it is relatively easy to avoid the holes, but spraying on a duct with limited room to work is probably going to result in a few holes.
Are these ducts very big? Are they set close to the roof deck, or suspended several inches above the deck?
Foam sprayed on ducting is likely not going to be very aesthetically appealing. In the end you may be better served by spraying the ducts, then installing a sheet of EPDM as a tent over the ducts. EPDM can be bought in white, so you can get the reflective benefit. EPDM is exteremely durable, and it is made for roofing. you would just have to figure out a way to attach it to the existing roof.