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    Default Flat Roof Operations

    When performing roof operations on a flat roof with built up membrane roof on wood joist, do you remove the membrane before cutting the ventilation hole? Why/why not? If so what is the best/quickest way to remove the membrane?
    Last edited by strask; 01-01-2010 at 05:05 PM.

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    I miss the Partner saw...Being a local vendor, the Beach and many Hampton Roads departments use Stihl products. The comparable to the K12 is the Stihl T460.
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    Quote Originally Posted by firefuss View Post
    K12 partner saw with a warthog blade. Keep the rpms high and you'll have a hole in a few seconds, on about every surface faced in the fire service.

    I second that 100%...Saw has two speeds. All the way on or all the way off.

    By screwing around with membrane, tar paper, or whatever you're just waisting time and taking longer to accomplish the task. The crews/victoms inside need ventilation right away so dicking around with that stuff isn't speeding up the process. Also, say your fire's in a 3-story frame. Well, you're standing on top of a 3 story lumberyard that's on fire. Do your job and get off.

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    Quote Originally Posted by len1582 View Post
    I second that 100%...Saw has two speeds. All the way on or all the way off.

    By screwing around with membrane, tar paper, or whatever you're just waisting time and taking longer to accomplish the task. The crews/victoms inside need ventilation right away so dicking around with that stuff isn't speeding up the process. Also, say your fire's in a 3-story frame. Well, you're standing on top of a 3 story lumberyard that's on fire. Do your job and get off.
    Yep what he said

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    We have a Sthil saw with just a standard metal blade I have tried talking the
    guys into buying a blade such as the warthog for it but they all seem to think they are to expensive. We also have a Shurvent chain saw. Would this work to cut through a flat roof as well?? Out old down town business district all have flat roofs and we need a way to vent them if needed.

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    Quote Originally Posted by JSMV72 View Post
    We have a Sthil saw with just a standard metal blade I have tried talking the
    guys into buying a blade such as the warthog for it but they all seem to think they are to expensive. We also have a Shurvent chain saw. Would this work to cut through a flat roof as well?? Out old down town business district all have flat roofs and we need a way to vent them if needed.
    You can vent a flat roof with a chainsaw. But if you hit metal joists, like Bar Joists, you will kill the chain pretty quick. But on old construction where more then likley it's wood, they work great. Just beware, because of the design of a chain saw, if you are cutting through a thick, multilayer tarred roof, you will be kicking up all sorts or tar that will gum the engine or YOU. Position yourself accordingly. Rotary saws are more popular on flat roofs for these reasons.

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    I have seen a chain saw gummed up pretty bad by cutting vent holes at a training. It cut about 5 4x4 vent holes and it was all full of junk. I really dont see this as a problem due to the fact that you are cutting one possibly two holes, or a trench. Then the saw is put away and can be cleaned rather quickly. Rotary saws cut cleaner with less gumming up, but depending on the thickness of the roof it may take two passes to get through which means a smaller hole and more time spent. All in all both techniques will work relatively well, better than using an axe.

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    Firefuss and Len: You guys have had no issues with rotary saws gumming and binding up when used on "rubber" membrane? I know of a few places that tried this and found that they couldn't make it more than one or two feet before the saw was toast with material stuck to the blade and up inside the guard.

    We've always been taught and passed on, that if you can seen the membrane (outermost layer) you cut it with a knife first and peel it back, only if this is the only option and the roof is safe.

    In visiting construction sites while the roof was being finished we found many with between 4" and 6" of Styrofoam insulation board over underlayment and topped with the rubber membrane. Of course this is all over the lightweight truss joists as well, and burdened with HVAC units and grease vents. Given this, we determined our rotary saws likely could not be very effective, as we had been taught, though actual experience is the true measure...

    WD: A Chainsaw on membrane? Again, it would seem to be possible only if the membrane was fastened between two other layers? I can see a real issue with flapping rubber when it's the top layer and not glued to the next layer down?

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    [QUOTE=RFDACM02;1130023]Firefuss and Len: You guys have had no issues with rotary saws gumming and binding up when used on "rubber" membrane? QUOTE]

    I don't recall ever cutting one of those. The buildings I've dealt with are mostly older ones. Also, any roof repair/replacement was plywood, tarpaper, tar, etc.

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    Quote Originally Posted by RFDACM02 View Post
    WD: A Chainsaw on membrane? Again, it would seem to be possible only if the membrane was fastened between two other layers? I can see a real issue with flapping rubber when it's the top layer and not glued to the next layer down?
    On rolled out rubber membrane not glued, i would just cut it with a knife or razor. It would literally take 30 seconds to get on you knees and crawl back 8 feet while dragging the blade. As soon as you start the next corner, start pulling it back and the OVM can start cutting. No more membrane issue. You could easily cut the section out and toss it to the side before the saw even gets to the third side of the cut. If the membrane is glued, then you just cut through it. It makes a mess, but it can be done.

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    Quote Originally Posted by DocVBFDE14 View Post
    I miss the Partner saw...Being a local vendor, the Beach and many Hampton Roads departments use Stihl products. The comparable to the K12 is the Stihl T460.
    A few years back, we purchased a K950A Partner. There was one older guy on the Department who didn't like it because "it had a compression release" (his words.) We won't mention the fact that he ran all Stihl equipment for his personal business, and that his neighbor was a Stihl sales rep. Eventually, he talked the powers that be into selling the K950A in favor of the 12 pound heavier, larger, less horsepowered TS450........What a piece of crap boat anchor!
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    Quote Originally Posted by WD6956 View Post
    On rolled out rubber membrane not glued, i would just cut it with a knife or razor. It would literally take 30 seconds to get on you knees and crawl back 8 feet while dragging the blade. As soon as you start the next corner, start pulling it back and the OVM can start cutting. No more membrane issue. You could easily cut the section out and toss it to the side before the saw even gets to the third side of the cut. If the membrane is glued, then you just cut through it. It makes a mess, but it can be done.
    This is basically how we've trained for these roofs. In the last few years (5-10) This method of roofing has been the predominant one on commercial buildings in our area. Almost all the chain restaurant buildings and large strip malls have done this as well as some downtown re-roof jobs.

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    Quote Originally Posted by WD6956 View Post
    You can vent a flat roof with a chainsaw. But if you hit metal joists, like Bar Joists, you will kill the chain pretty quick. But on old construction where more then likley it's wood, they work great. Just beware, because of the design of a chain saw, if you are cutting through a thick, multilayer tarred roof, you will be kicking up all sorts or tar that will gum the engine or YOU. Position yourself accordingly. Rotary saws are more popular on flat roofs for these reasons.

    If your not using them already, these chains are worth every penny:

    http://www.cuttersedge.com/Products/...8/Default.aspx
    wouldn't you be worried about cutting a joist w/ the chainsaw?

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    Quote Originally Posted by fdny84 View Post
    wouldn't you be worried about cutting a joist w/ the chainsaw?
    Not if you don't plunge it too deep. Also, when you're cutting with a chainsaw you'll feel some resistance (for lack of a better word) as you touch the joist. Just pull back on the saw a bit.

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    so if we have a cutters edge and a k12 on the truck, would it be our best bet to pull the k12 and take it with us to play it safe not knowing the age of the building and what materials we may be cutting into?

    we have a warthog on our k12.

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    Quote Originally Posted by CowboyD Eng6ine View Post
    so if we have a cutters edge and a k12 on the truck, would it be our best bet to pull the k12 and take it with us to play it safe not knowing the age of the building and what materials we may be cutting into?

    we have a warthog on our k12.
    We usually base our decision on the pitch of the roof. I like the K saw on low pitches where I can stand without the assistance of a ground ladder or other purchase. Anything steeper I like the chainsaw. Luckily this sort of coincides with the roofing materials in most cases.

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    Quote Originally Posted by WD6956 View Post
    You can vent a flat roof with a chainsaw. But if you hit metal joists, like Bar Joists, you will kill the chain pretty quick.
    Forget the chain...if you hit a bar joist with ANY type of saw, you can likely kill YOURSELF.

    You should NOT be sinking a saw into a membrane roof with steel bar joist construction!

    There can be as much as 8 feet of spacing between steel bar joists. So either the ventilation hole you are making is being supported by NOTHING on either side of the cut, or worse, the cut is directly over one of the bar joists and you cut the top chord of the bar joist, which is a truss, therefore rendering it useless and prone to failure.
    Last edited by jakesdad; 02-02-2010 at 03:48 PM.

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    Quote Originally Posted by RFDGloWorm View Post
    This is what we run on all of our chainsaws. They are so much more effective than bullet chains.

    On flat roofs with drop ceiling also be sure not to plunge too deep or you will end up with a wire wrapped chainsaw.

    Nothing holds up to commercial flat rood ventilation like the Partner K-12 with Warthog blade.

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    Quote Originally Posted by jakesdad View Post
    Forget the chain...if you hit a bar joist with ANY type of saw, you can likely kill YOURSELF.

    You should NOT be sinking a saw into a membrane roof with steel bar joist construction!

    There can be as much as 8 feet of spacing between steel bar joists. So either the ventilation hole you are making is being supported by NOTHING on either side of the cut, or worse, the cut is directly over one of the bar joists and you cut the top chord of the bar joist, which is a truss, therefore rendering it useless and prone to failure.
    Guess we don't know anything about roofs.Been cutting 'em for over 40 years with a SAW,all types. You need to know WHAT you're cutting to know HOW. For membrane roofs, it's the K12 960 with a Warthog here.If not available it will be the 550 Stihl. Steel trussed roofs can be swiftly and easily cut with a rotary saw and it doesn't take a genius to figure out where the Chord is and avoid it. If you're VENTING the roof,real GOOD chance that truss is going to be exposed to a failure element anyway. Get it done and get OFF. T.C.
    Last edited by Rescue101; 02-18-2010 at 10:13 AM.

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    Quote Originally Posted by fdny84 View Post
    wouldn't you be worried about cutting a joist w/ the chainsaw?
    As Len pointed out, it's all in your depth. Most vent chainsaws have a depth guard to allow you set the cut to any thickness you want and then you can cut without any issues. Even with an 18" bar it's not like we plunge the bar in halfway. It's set for 2-3" in most cases. And like he said, you could tell by feel if you were cutting a joist instead of just decking.

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    Quote Originally Posted by jakesdad View Post
    Forget the chain...if you hit a bar joist with ANY type of saw, you can likely kill YOURSELF.

    You should NOT be sinking a saw into a membrane roof with steel bar joist construction!

    There can be as much as 8 feet of spacing between steel bar joists. So either the ventilation hole you are making is being supported by NOTHING on either side of the cut, or worse, the cut is directly over one of the bar joists and you cut the top chord of the bar joist, which is a truss, therefore rendering it useless and prone to failure.

    First of all, chainsaws and rotary saws with typical blades will not easily cut through steel. If you hit steel with either type of saw, YOU WILL KNOW. By the sound, by the feel and by the shower of sparks shooting out instead of sawdust. I have yet to strike a steel joist with a power saw and not known almost instantly. You will know long before you cut the top chord of the joist. If you cannot tell when your saw is cutting a steel joist. You should not be using a saw and likley should not even be on the roof because you lack common sense.

    That issue aside, when it comes to flat roofs, we have a policy where we do not go on a steel deck roof, period. They are extremeley dangerous for reasons like you mentioned above. The steel decking material will not hold weight if you cut it near the end of an unsupported sheet.

    BUT, there are bar joist supported roofs with wood decks. I have seen bar joists running one way and 2x10's running the other way. These types of decks will easily support the weight above when cut.

    If you arrive on the scene of a commercial structure fully involved with a flat roof and you have no idea what type of roof support it has, are you even going to set foot up there? Or would you wait till an interior crew gets inside to tell you what it looks like? They may not even be able to tell. A sheetrock ceiling will make it difficult to determine the type of roof support. Untill we can confirm with certainty what we are about to walk on, we don't. Especially with a commerical fire with no possible occupants trapped inside. Cutting a bar joist is the absolute least of our concerns. First and foremost, what is the decking made of? Sometimes you can tell just by looking at it. Or we can walk onto an area we know is not burning below and make a determination with some prodding.

    As long as builders want to use cheap materials to save time and money at the risk others in the event of a fire, then we will continue to use extra care in sizing up those fires. But i myself, nor my brothers are going to put our lives at risk to save a commercial building by venting a possible deathtrap of a roof.

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    One of the many reasons you're seeing more and more Platform/Tower Ladders. A majority of our flats are membrane over wood. The steels are cut with Diamond blade.Because of the "snow load"requirements for our area you CAN cut the steel without falling thru. Only have had to cut two in recent memory and both were for small area extention fires.Our "commercial"area is small enough so that we can preplan these buildings and have a good Idea what we will be dealing with PRIOR to an event. VERY helpful and not practical for understaffed,and larger agencies. Here,we can see and photograph a new building as it is being built and add it into our training. AND know which roofs to stay OFF of. T.C.

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    Cool Our Experience and Training

    Our experience and training has shown that it's quicker and easier to use a Straight Blade/Packing Knife and cut the membrane. I keep an Irwin Straight Blade in my Turnout Pocket and use it on the membrane. Another great thing is that as a C.O. it makes it perfectly clear to my Guys where I want the hole. I recently attended a Truck Academy in the L.A. Area and that is also how they'll do it, but again that varies from Department to Department. Other Departments cut with their Rotary Saws.

    My suggestion, set-up a Training Prop and try the ways that you've learned. Time all the evolutions and see which one is most efficient for your Department.
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    Quote Originally Posted by WD6956 View Post



    If you arrive on the scene of a commercial structure fully involved with a flat roof and you have no idea what type of roof support it has, are you even going to set foot up there? Or would you wait till an interior crew gets inside to tell you what it looks like? .

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