TORCH-APPLIED MEMBRANES AND FIRE

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Author Message Wayne Yancey Senior Member Username: wayne_yancey Post Number: 212 Registered: 01-2008 Posted on Friday, June 12, 2009 - 04:10 pm:    WARNING, WARNING DANGER, DANGER A massive fire completely destroyed a 29-unit condominium development under construction in Coquitlam, B.C. on the morning of June 11, 2009. Media reports said a roofer using propane sparked the blaze, but an eyewitness who was working on the project said the fire was started by a worker applying torch-on to the base of a building just before 10 am. Two buildings that were nearing completion (had already been inspected by engineers) were burnt to the ground. A townhouse next to the development was severely damaged by the blaze. Firefighters attacked the flames from three points had the fire under control in a little more than an hour. Three fire fighters were injured and one was sent to hospital with a back injury. The assistant fire chief for Coquitlam said the cause of the fire is still under investigation. OUCH! Richard A. Rosen, CSI, CCS, AIA Senior Member Username: rarosen Post Number: 45 Registered: 08-2006 Posted on Friday, June 12, 2009 - 04:19 pm:    This is a well known and documented problem with torch applied membranes. So much so that many municipalities do not permit torch application on combustible roof construction and some require a fire watch and fire extinguishers on the roof for up to 2 hours after the completion of operations. Don Harris CSI, CCS, CCCA, AIA Senior Member Username: don_harris Post Number: 222 Registered: 03-2003 Posted on Friday, June 12, 2009 - 05:13 pm:    We had a similar incident. Wood framed building, contractor wanted to substitute torch down. We said no. Owner said yes. Barbecue followed. Thankfully it was extinguished quickly and only part of the roof had to be replaced. And no injuries. But you just have to wonder about the mindset of mixing wood frame and fire. What are they thinking? Wayne Yancey Senior Member Username: wayne_yancey Post Number: 213 Registered: 01-2008 Posted on Friday, June 12, 2009 - 05:23 pm:    Don, Aside from what were they thinking regarding torch-on. What were they thinking about proceeding without a fire watch and fire extinguishers as noted by Richard. This is the 2nd BIG fire I have heard about in Canada in the past 10 years. A similar fire bombing took place at Earlton Station in Calgary, Alberta. Took out an entire block. I had a project go up in flames in Calgary in the late 70s. Only one block of units burned to the ground but the radiant heat did it's damage to both the plastics on the fire trucks and the interior window treatment in the units across the road on the same site. Margaret G. Chewning FCSI CCS Senior Member Username: presbspec Post Number: 173 Registered: 01-2003 Posted on Saturday, June 13, 2009 - 09:59 am:    When I was living in New Orleans, 21 years ago, I remember a devestating fire at the museum adjacent to the cathedral in Jackson Square in the French Quarter. The cause was smoldering sheathing that burst into flame during the night after the torch down roofing crew left for the day. So a 2 hour fire watch is not enough. Jo Drummond Senior Member Username: jo_drummond_fcsi Post Number: 33 Registered: 06-2007 Posted on Sunday, June 14, 2009 - 08:02 pm:    Thank you for this thread! I always try to convince architects and owners not to use torch applied roofing on wood frame buildings because of the fire danger. Roofing manufacturers promote torch applied because it is cheaper than cold applied,which has some problems of its own, but it doesn't burn the building down. Richard L Matteo, AIA, CSI, CCS Senior Member Username: rlmat Post Number: 330 Registered: 10-2003 Posted on Monday, June 15, 2009 - 12:24 pm:    My firm does not specify or allow torch-applied roofing either. Especially in California during wildfire season! I had a situation some yars ago on the East Coast, where a roofer almost burned down our office when he set the wood roof members smoldering. Fortunately it was an exterior porch roof. It was on a Friday, and had it not been discovered it could of had devastating results. ken hercenberg Senior Member Username: khercenberg Post Number: 23 Registered: 12-2006 Posted on Friday, June 26, 2009 - 11:16 am:    To be fair, I've had great success using torch-applied mod bit systems over the years, with several hundred thousand square feet of roof in-place. There are, as noted in this thread, a couple of simple rules that, until reading this, I would have thought to be inherently obvious to anyone: 1. Only apply torch-applied systems to non-combustible substrates. The only fire-related problem I have ever encountered involved the plywood wall sheathing at a parapet situation that was not constructed as detailed. The two roofers tasked with overnight fire-watch were able to take care of this with little difficulty and resolved the in-place installation the next morning. 2. As noted in Item 1 above, always specify a two-person overnight fire-watch detail every time you specify torch-applied assemblies. 3. Always require that fire safety and acknowledgement of ‘who supplies the fire extinguishers during construction’ in on the agenda of the roofing coordination meeting. I don’t care who provides the fire extinguishers, GC or Installer, as long as they are on the roof when they are needed. 4. Don’t think that eliminating torches and kettles means that your roof is automatically fire-safe. Many cold-process and single-ply roofing systems involve the use of highly combustible solvents. Even with ‘No Smoking’ required by LEED and by law, many construction workers still find ways to ‘sneak’ a cigarette. In fact, no longer able to smoke openly drives many to smoke where no one will notice which means they may be sitting among the cans of adhesive, solvent or gas. Torch-applied mod bit systems are easier to detail than most other systems available, especially at critical flashing and penetration conditions. They maintain the original intent of mod bit systems, namely melting the various plies together to create a homogeneous membrane rather than gluing the plies together, the result of mop-down and adhesive systems. Please don’t discount the value of a good system because it was applied improperly by those who didn’t know better. Last I checked fire was still considered a useful invention; we just have to use it wisely. John Bunzick, CCS, CCCA, LEED AP Senior Member Username: bunzick Post Number: 1060 Registered: 03-2002 Posted on Friday, June 26, 2009 - 11:42 am:    I've not used these systems, but wonder if the use of thermal-imaging cameras to locate hot spots (after work stops for the day) has ever been considered or used by anyone. ken hercenberg Senior Member Username: khercenberg Post Number: 25 Registered: 12-2006 Posted on Friday, June 26, 2009 - 04:59 pm:    John, that would make too much sense, especially since IR doesn't cost much, especially compared to the cost of rebuilding an entire building. Actually, even with that, I'd want a fire-watch. The problem is that some of these fires start out so small that, buried under a couple of plies of membrane and probably some insulation, the thermal image might not be sufficiently conclusive until it's too late. Richard A. Rosen, CSI, CCS, AIA Senior Member Username: rarosen Post Number: 46 Registered: 08-2006 Posted on Monday, June 29, 2009 - 10:17 am:    Another shortcoming of thermal imaging is it requires a temperature differential for the hot spots to be seen. In my experience the scans are done at sundown or later. On new construction more than likely the interior and exterior ambient temperatures are very close to equal so there wont be any temperature differential from heat loss to read. The fires that start under the torched down membrane normally smolder for quite sometime before erupting. Phil Kabza Senior Member Username: phil_kabza Post Number: 391 Registered: 12-2002 Posted on Monday, June 29, 2009 - 03:08 pm:    So ... torch-down roofing systems are ok if: 1. You have qualified, competent installers. 2. You have proper fire protection equipment at hand. 3. You maintain an adequate fire watch. 4. You perform a thermographic scan following installation. At what point are these qualifications so demanding that they are simply unlikely to be fulfilled on the job site? How much CA control are you assured of exercising? Has anyone asked their risk managers' opinions on issuing a specification like this? We can always put QA/QC requirements in clear, complete, concise, and correct text. But all of this starts to read like a "Beware of Vicious Dog" sign: If you are admitting to harboring a known vicious dog, why are you warning people instead of getting rid of the problem? ken hercenberg Senior Member Username: khercenberg Post Number: 26 Registered: 12-2006 Posted on Monday, June 29, 2009 - 03:59 pm:    Many people who have spent too much time providing forensics on failed roofs understand that torch-applied mod bit is still among the best options available in an industry where anyone can sell a roof membrane regardless of whether or not it works. As long as there are those who spend more money on marketing warranties instead of proper detailing and long-lasting roof products, adding a few simple instructions is a small price to pay for a quality result. Don't you always want 'qualified, competent installers', regardless of roof system? I'd eliminate 'proper fire protection' from your list since, again, you need that for most roofing systems during application. The IR scan is not practical for the reasons pointed out earlier. Seems to me that the only real 'added' cost is an adequate fire-watch. Sure beats having to explain to your client why they have to live with 10 years of leak repairs before tearing off a roof and replacing it. John Bunzick, CCS, CCCA, LEED AP Senior Member Username: bunzick Post Number: 1061 Registered: 03-2002 Posted on Monday, June 29, 2009 - 05:12 pm:    Richard, Thermal imaging for wet insulation is done, as you describe, after dark to get the temperature differential. I think if there was some smoldering wood under the membrane (notwithstanding Ken's observation), you would have sufficient temperature difference as the burning emits heat. Systems are more sensitive now than they used to be, as well. As Ken notes, not a substitution for a fire watch.