Roof-overs. We talk about them occasionally, but we dont often address how they look and feel on the fireground. They often get installed without our knowledge, and they make interior and exterior operations very difficult if the new construction cannot be addressed in a timely fashion. So what do we do, since we cant inspect private homes or watch every neighborhood or business for renovations? How do we gain early detection of this potential problem? First off, like all issues on the fireground, sizeup is your best tool. Early and continuously. If you arrive and find a house with a dramatically different pitch or style than the rest of the area, that can be an indication of a roof-over. Same with commercial roofs, though flat roofs are very difficult to decode from the ground. Ongoing sizeup should also tell you if the conditions you see outside arent matching what guys inside are telling you. For instance, if exterior signs point to attic or cockloft involvement, but interior crews arent finding anything, or they say they have it knocked down, your next assumption should be some sort of void space involvement. Next on the list of diagnostic tools is the roof crew. If there has been no indication yet of a roof-over, the roof crew should find it very quickly, before crossing the roof. Many vertical ventilation instructors teach the diagnostic cut for commercial roofs, in some form or another. I take it a step further; Im a big proponent of diagnostic cuts on residential roofs as well. These days, with cold roofs, spray foam insulation, and roof-overs, any pitched roof has the potential to be hiding a cornucopia of tricks and traps. A quick diagnostic hole, just big enough to shove an arm into, is the key to undressing the entire roof before you step away from the ladder. It tells you construction type and direction. When done near the gutterline, it allows easy detection of a roof-over. Youll know if theres 12 of spray foam sealing the attic up airtight. Youll know if theres a cold roof system that will require different tools or manpower before you traverse 30 feet of roof without them. So, clearly, any abnormalities have to be passed on to the interior crews and the operations sector. Addressing the issues is the next step. If you have a roof-over, your diagnostic cut needs to be extended through the next layer of roof so you can figure out what is ultimately holding you up. Consider that an additional roof may or may not have additional structural support. It may not need it, or it may need it and not have it. Just know that our lack of a structural engineer on scene with blueprints means we have to use our noggins as more than hat racks. Sounding is still important. Fire in the void space means that the top layer of roof may be compromised, even while the structure is sound. Fire in the attic, however, may impact the structure without any change in the sound and feel of the top layer of decking. If you did your diagnostic cut, you already know this, and you can periodically pop smoke indicator cuts through both roofs. This also helps you find the correct location to make your vent hole, since the roof-over can hide some of the indicators youd normally see. When its time to get down to business, efficiency and efficacy are the goals. Efficiency so we spend as little time over the threat as possible. Have an operation that you and your crew have trained on until its second nature. Efficacy of hole placement may be hampered by structural compromise. It may be necessary to pull back and sacrifice efficacy for a little more time to perform the more labor-intense operation. Again, this less-desirable hole acement must be communicated so that interior crews can adjust for possible fire spread toward the hole. Still, well take that trade-off if it means better conditions for everyone below. The nuts and bolts of cutting two roofs is pretty simple. Some of the challenges are that as you approach the peak of some roof-overs, youll find that theres a steeper pitch on the outer roof that makes a foot or more drop betwixt the two roofs. Even same-pitched roof-overs, like on flat roofs, can have a significant drop. This creates a second cockloft. When opening the top roof, make the hole bigger than you need. This allows room for the bottom roof to be opened without roof decking or tools being obstructed by the top roof. This is similar to how youd attack a built-up commercial roof. Keep in mind that the rafters on top will get in your way when cutting the roof below. Id leave them in place and cut betwixt them to preserve as much roof integrity as possible, since sounding and diagnostics are impaired. Also, be EXTREMELY cautious of putting someone down on the lower roof. As stated, theres a significantly impeded ability to sound the lower roof. Theres also a great deal more difficulty escaping the area should things go bad. Youre likely standing on top of your own workspace, which means your hole may end up much smaller than intended. Small may be better than nothing, but there is a point at which the diminishing return makes it hard to justify the increased time and danger over the seat of the fire. The attached picture is of a recent fire we had. Not only had the original house been added onto, but there was a roof-over on the addition. You can see that the original roof rafters rest about directly on the top plate of the wall, and theyre single two-by boards. They point directly at the camera and sit on the header. On the original rafters rests a boxed out frame running perpendicular to the rafters. In this case, it makes about an 8 space betwixt upper and lower roof rafters. The upper roof rafters then rest on the box framing. The roof-over was actually built with doubled two-by rafters, and was the same pitch as the original roof. Interior operations were significantly complicated by all the void space fire on the addition. There were no roof ops on this heavily progressed fire, but the rapid fire spread and difficulty in opening up and getting water on the fire made it a rough one. Had there been any topside ops, the roof-over wouldve slowed things, but a 12-16 drop is workable.
Posted on: Thu, 17 Jul 2014 02:46:06 +0000
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