Or Please define Roof Deck?
Thanks
All the time. Most times insulated (over conditioned space), sometimes uninsulated. It needs to be waterproof regardless. I may have insulation over (PMR) or under the waterproofing membrane.
If you are referring to a deck as an outdoor space that you can stand on, and not a structural element, then a Roof Deck would be an out door space you can stand on that is over a living space that is below it. It is also a very probable water intrusion point and future source of litigation in multifamily construction that should be avoided like the plague.
Nathan, I work on many multi-family projects, both rental and condo, and you are correct Smart Architects avoid placing elevated decks over habitable space, but it does happen, and many times the space is habited by a Corvette or a Maserati, not human, but the litigation still exists.
I’ve been waiting a year for an AHJ to rule on whether or not a melter would be allowed on an elevated deck for application of Hot Fluid Applied membrane, NFPA says kettles are not allowed, but its not clear about melters.
After a years wait, the AHJ answered as follows:
“No placement of Kettles/Melters on top of roofs. They are not allowed.”
Thus my question regarding a definition of a roof deck versus an elevated deck. Most architects in Florida know you can no longer specify hot membranes for roofs, this is not what I originally asked. My query was whether or not a hot membrane could be used on an elevated deck as waterproofing.
Historically, Hot membranes work very well for waterproofing elevated decks, is products by American Hydrotech. But having a kettle on the deck has proven dangerous, and many believe melters are jus as bad, of course not the reps for Hydrotech, they believe that melters are completely safe.
The following is the original query to the AHJ from the job Building Envelope Consultant:
"Please would kindly let us know whats the Building Department position in regards to the Hot Fluid-Applied roofing/waterproofing systems, and the placement of Kettles/Melters on the job sites.
There have been a controversy with some hot fluid-applied manufacturers and some municipalities fire marshals on this subject. We have heard that the Fire marshals Committee have been discussing the issue; however the approach may vary between municipalities.
From our end, as exterior envelope consultants (including roofing and waterproofing), our approach have been not recommending hot fluid applied systems until this matter is more clear."
The AHJ answer:
“No placement of Kettles/Melters on top of roofs. They are not allowed.”
Comments Please?
Sounds like the membrane is permissible to use, but you’ll need to hoist the kettle/melter up adjacent to the deck area being coated.
Nathan, there is no such thing as a kettle/melter. It is either a kettle defined by NFPA and not allowed, or a melter, good luck on getting a definition on a melter. And this is how the problem started over a year ago, a melter was hoisted to an elevated deck and the Fire Marshall said it was not allowed as the melter was in violation of NFPA.
It looks like I am going to have to spec a torched membrane.
Jerome, sounds like you are steamed about that decision.
Dave, that sounds like a pun, its been a long day, first a worthless answer from the AHJ, now an emergency dentist appointment…from one pain to the next, such is my life.
Jermome, I was being all inclusive by saying Kettle/Melter. I almost wrote “heat source” instead. As for the hoisting, I did not say TO the roof, I said adjacent to the roof, as in, not touching the roof, but remaining suspended above.
What is the applicable NFPA that prohibits kettles on roofs?
Its actually from the Florida Fire Prevention Code (FFPC):
16.7.1 General
16.7.1.1 The provisions of Section of 16.6 shall apply to any type of equipment including, but not limited to, chassis-mounted equipment used for preheating or heating tar, asphalt, pitch, or similar substances for roofs, floors, pipes, or similar objects.
16.7.1.3 Operating kettles shall not be located inside of or on the roof of any building.
I’ve been told that the FFPC is derived from NFPA, all I know is, in Florida, the FFPC is law.
Ron, melters/kettles are not illegal if maintained on the ground. It is the placement of the heating apparatus (melter/kettle) on an elevated building surface that is illegal. The Fire Marshalls have been very clear that the height from the ground is not relevant - an apparatus is either on the ground or it is not.
so, Jerome, your reference to NFPA in an earlier post may have been incorrect?
Rather than a torched-applied system, have you considered a cold adhesive-applied system? Torched-applied are avoided in my area of the country, and not allowed in several jurisdictions.
Ray, the FFPC adopted NFPA, they are one and the same in Florida.
Cold applied WP does not have the history of success as does hot applied in Florida; on the same project we specified a cold applied system, but we can only get a 10 year warranty, but the client wants a 20 year warranty which is typ with hot membranes.
Ron, NFPA 1: Fire Code, Section 16.7: Tar Kettles.
Jerome, to Nathan’s point, the code doesn’t say the kettle has to be grounded. It just says not inside of the building or on the roof of any building. Doesn’t mention anything about suspending it adjacent to the roof or even over the roof. I wouldn’t necessarily try to get this to past the AHJ, however.
Back to the original question…
I would say that an elevated deck is a structure designed for pedestrian or vehicular use constructed over unused or unusable space (such as a crawl space) while a roof is a structure designed to protect the space(s) below from sun and inclement weather. Roofs may also be designed for pedestrian or vehicular use.
Here in Houston, the AHJ has restricted the use of of “kettles” on high rise construction in the CBD. One of the major waterproofing company has special kettles that they are able to use in these situations. These kettles have a lower capacity, and there are special permits that are required, but they are able to comply with the restrictions using this equipment. If you are interested in knowing more, email me and I will send you contact information.and I will send you
In regards to hot vs. cold applied membranes, I’ve only seen a couple of really good cold applied membranes and both were taken off the market by their competition. Pretty odd but what can you do. If the surface will be subject to traffic, you may want to consider a PMMA membrane. It has horrible elongation (which I think is critical for a roof) but excellent resistance to damage from traffic.
As to melters, my understanding is that they are defined as double-jacketed containers that work like a double-boiler. The oil in the outer chamber is heated which in turn heats the bitumen in the inner chamber. It is required for SEBS modified bitumen. Both kettles and melters can explode and start fires if not properly tended though I’ve never heard of that happening with a melter. Pumping trucks are popular if the high-rise isn’t too high. The problem is that the pumping line can split and cover the building and neighborhood with hot bitumen.
As to an elevated deck vs. a roof, I would consider a roof structure to be a subset of an elevated deck. Not all elevated decks are roofs but typically roofs are elevated decks. Roofs are not typically designed for use as a traffic surface. I believe that your suggestion of calling the membrane ‘waterproofing’ instead of ‘roofing’ at that sort of condition is accurate. However I do not believe that it will allow you to circumvent the heated vessel restriction.