In New York solar installations are required to have all penetrations flashed - chemical sealant is not flashing. An asphalt rooftop that sees temperature swings from -20 to 130F are a concern for simple thermal movement and I lost count of how many L feet I have seen with half a tube of silicone or worse yet Sikaflex goobered all around them. Ask any roofer what he thinks about drilling through the roof and relying on purely a chemical adhesive/sealant for the prevention of water intrusion, and he will laugh at you.
NYS Building code 1503.2 is the primary reference for requiring flashing for all roof penetrations. The NYS 2010 residential code M2301.2.7, R903.2 all refer to 'flashing' and sealing. The National Roofing Contractors Association provides guidance for asphalt shingles and penetrations. Checking with many roofing manufacturers also has shown that they require flashing penetrations to maintain their warranties - not using flashing is a violation of the roofing installation instructions. Yes it is more expensive - but it is like insurance, you don't need it until you need it, but then there is no substitute for it. Of course if you are big enough with deep enough pockets you can take more chances with roof penetrations, and maybe you will not run into a call-back for a leaking roof. But if you do, wouldn't you have a stronger position with the customer by saying all penetrations were flashed in accordance with standard roofing contractors and manufacturer's specifications instead of 'well I shot everything full of sealant and it is what I have been doing for years/hundreds of holes in roofs'. I can't see in this day and age any reason not to use one of the many commercially available flashing solutions. Now 5 years ago, was a different time, and we formed our own flashing out of Al coil stock because there was no good solution available at that time. Hope this helps in your decisions. Glenn Burt One of many inspectors for the NYSERDA PV and Thermal incentive programs. From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Troy Harvey Sent: Friday, April 11, 2014 3:20 PM To: RE-wrenches Subject: [RE-wrenches] Flashing vs Sealant... again (is sealant code defensible?) 1. I'm interest in a poll of installers who are using flashings vs sealant. Now that the flashing market has evolved, what are you using today? When did you switch to flashings (if you did). And why not, if you still prefer sealant. 2. Is there a any code defense for sealant systems ? (L-foot sealed down to shingles). Does anyone know of a scientific shootout between sealants and flashings? Here is my view: The construction industry is slow to evolve. Sealants, clauks & adhesives are not trusted in general, due to the legacy of code, and we have a mechanical vs. chemical industry bias. There is something about seeing a flashing that says, that is a "professional job", it must comply with code. And yet, my experience says I'd trust a 50-year silicone over a flashing that depends on gravity. Gravity should be dependable right? But anyone in snow country can tell you in spring, water can go uphill after ice dams form. There are high-rise buildings that use "structural glazing" which is just glass and silicone. These systems are now getting to be 50 years old without issue. The cost of flashings have come down in the last few years, but so has the cost per watt of installs. With 50 feet in a typical install around here that is $150 in feet, lags & silicone. Or $1500 in flashings, and extra labor. That can be a large part of a bid, and make you more expensive in a competitive landscape. That is fine, if it adds value... but I personally don't see the proven value, other than the "appearance" of code defensibility. Anybody have proof? thanks, Troy Harvey --------------------- Principal Engineer Heliocentric 801-453-9434 tahar...@heliocentric.org
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