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  1. #1
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    Angry Prefab Roof Panels -How to ventilate

    Anyone out there have experience with performing ventilation of prefab roof panels. Specifically "Green" construction with double sandwich assembly using 5/8" ply on inside and two layers of 6" styrofoam sandwiched under OSB boards. How the Heck do you cut through 16 inches of roof and after you do what stops you from burning the entire roof of styrene off the structure?


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    Good question... We're just now starting to see some of this type building construction in our area and I was thinking the same thing... Haven't measured the exact depth the panels so not sure how deep the cut would need to be, but in looking at the panels i'd say regular chain saw...

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    Perhaps you can give more info about this. What kind of building used this, is it def styrene based and not some glucose material. Pics would be great too.

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    I have not seen material yet. Very interesting! Can someone get their hands on some scraps, 6 inch by 6 inch piece would do. I want to do a field combustibility test. Most of the new construction foam will not sustain combustion. We need to know how this material burns to evaluate how much of a threat as additional fuel load it might be. Does it burn quick, slow or not at all?

    When fire is cried and danger is neigh,
    "God and the firemen" is the people's cry;
    But when 'tis out and all things righted,
    God is forgotten and the firemen slighted.
    ~Author unknown, from The Fireman's Journal, 18 Oct 1879

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    normally you would use a step cut, where you make a cut 25% larger than you want, and then cut the smaller hole inside the big one.

    in this case it sounds like it would take forever to accomplish, and the roof materials wouldnt hold up worth a damn under fire conditions anyways. I would opt to use horizontal vent.

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    MembersZone Subscriber MattyS's Avatar
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    Quote Originally Posted by jonnyirons2 View Post
    Perhaps you can give more info about this. What kind of building used this, is it def styrene based and not some glucose material. Pics would be great too.
    http://www.design101.tv/v2.0/sips.php

    It seems this can be used in all construction, from modular to commercial (can replace the OSB with light guage metal), remodels, additions and obviously new construction.

    From the Company website:
    Is EPS a fire hazard?
    We use "Modified EPS" which contains flame retardant additives that improve its burning characteristics compared to the EPS variety we are so familiar with in our disposable cups and packaging materials. EPS products will progressively distort, soften and melt when exposed to temperatures in excess of 175°F. As exposure temperatures continue to increase, combustible gases given off by molten residue will ignite in the presence of an ignition source. This temperature level, referred to as the flash ignition point, is approximately 700°F for modified EPS. This value may be directly compared to flash ignition temperatures for white pine and Douglas fir of 500° F.

    Unlike wood, however, MEPS makes a very small fuel contribution because it contains only about 3% combustion material by volume.

    In addition, most building codes require interior wall and ceiling surfaces covering foam insulations to provide a 15-minute rated fire barrier. Insulspan panels meet this requirement with the installation of drywall on interior surfaces.
    Attached Images Attached Images      
    The good thing about this job is that we have done so much, with so little, for so long that we can do everything with nothing...... which is what is wrong with this job.
    KTF | DTRT

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    Quote Originally Posted by LeatherHed4Life View Post
    in this case it sounds like it would take forever to accomplish, and the roof materials wouldnt hold up worth a damn under fire conditions anyways. I would opt to use horizontal vent.
    I was thinking the same thing. If you did chose to cut a hole it would seem like you could use a saw with no depth gauge and it would work. But I never have seen or heard of the SIP until now. Anybody ever had expierence with it??
    Knowledge is the difference between KNOWING and GUESSING

    "You guys are good, but you'll never invent anything-it's all been done before."

    FF/EMT-IV (medic in training)

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    I dont see what the benefit of it is? It doesnt look like it would be a roof material. It is marked R26 on the panels, Judging by the thickness you could get R30 insulation in the same space. Looks like this would be used in warehouse type buildings.

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    The reason I posted this question was because we were faced with this problem last Wednesday night. We were the mutual aid company on a heavy timber McMansion supplying an engine, quint and tanker to the scene. The home fire company thought they had contained it to the 8 stall garage area, when the cathederal ceiling in the living area lit up. Application of a heavy caliber stream from the aerial only served to fan the flame. Limited water supply and the massive volume of fire from the combined burning of the OSB board and the foam forced the aerial to abandon its position. Aerial was about 50 feet from the structure. Turntable operator was amazed that he needed to shield his face while bedding the ladder. Defensive action required two 1 3/4 streams on the neighboring residence about 120 feet from the fire. Finally got control of the structure after the roof fell in. The pictures of panels posted in this thread are similar to the roof panels, but the inside was 5/8" finished plywood, 6" of foam, a 1/2" OSB board, another 6" of foam, and finally a 5/8" top OSB board. The advantage is these panels can be hoisted onto the roof, reducing on site labor. Eventual water supply included hydrants (?? GPM), Tanker shuttle (56,000 gallons) and nearby pond late in the operation. Thanks to all for your inputs.

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    I do not know if I would want to get on a roof of this material at all, I would liken it to a gypsum plank roof. If I had to vent it, I would say that a chainsaw is the only way to do it, that or a handsaw! LOL

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    another thing to think about when this is used in roofing materials, depending on the overall insulation level of the attic space, in peaked residential dwellings it would probably mask the true fire conditions inside the attic.

    crazy ish

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    How about spacing of the rafters? Does this allow it to be changed? its 16 on center here in NY.

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    Quote Originally Posted by jonnyirons2 View Post
    How about spacing of the rafters? Does this allow it to be changed? its 16 on center here in NY.
    In a truss system you go to 24". Also, the foam gives a higher R rating. Apparently, there is also the added benefit of no seams and a tighter building.

    Sounds like we need to sharpen up the ice auger and use it like a big drill bit. Maybe shorten it too.

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    Are they used with a truss roof? Some have 48 inch spacing and larger.

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    So in residential it looks like they use either T-Joists or other laminated beams to run gable to gable then rest these panels full length from wall to ridge! Follow this link for their photo gallery:http://www.design101.tv/sips-photo-g...=3&show_mod=11

    Basically, I never trust any building products that are marketed as a "system" as this tends to mean, one part fails, the whole thing fails.

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    couldnt they use purlins to run over the trusses, then lay the panels on the purlins.

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    From looking at their online information, the panels can be used for walls, floors and roofs. Previous poster was correct, for a roof the panel would span from the wall to a ridge beam. No joists or trusses at all, only the panel. It looks like the floors are the same except they would run between walls.

    There is a push underway in the building industry for what are called green buildings. There are a lot of things that go into considering something a green building, and one of them is reducing heating and A/C costs. It sounds like they are pushing this material for that use. They are making these buildings much tighter, meaning they will also hold heat more effectively in a fire. In addition to collapse hazards, I think you would get into a lot of fire spread and backdraft or flashover hazards with buildings this tight.

    I would be interested in seeing some photos from the incident mentioned if you have any.
    Thomas Anthony, PE
    Structures Specialist PA-TF1 & PA-ST1
    Paramedic / Rescue Tech North Huntington Twp EMS
    The artist formerly known as Captain 10-2

    No, I am not a water rescue technician, but I stayed in a Holiday Inn Express last night.

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    From what it looks like the panels are made from the blueprints, shipped to the site and assembled as complete walls. A sill plate is added and LVL's or other type joists are added and the floors go up. Roof is same as usual, but depending on the load they are presented with can change the spacing of the rafters. I think this one may come down to a 3 little pigs scenario, and I do not see this system going in to our hurricane states or the tornado lane.

    http://www.insulspan.com/professionals/sip_system.html

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    These panelized systems have been in use for over twenty years in the timberframe / post & beam construction industry. They have many advantages over "normal stick built framing systems , speed in installation [quick close in of the building shell] higher r-values than fiberglass batt or blown in insulation, low air infiltration rate ,moisture barrier not needed. The down side is while the structural strength is great while the panel is intact ,once impinged by fire they will weaken rapidly and we should not be putting crews on them for vent operations. They also vary in the foam materials used , some have a low flame spread rating others, not good and will support combustion with toxic off-gassing. Another often seen problem with these here in the north is they are often covered with standing seam metal roofing. Slippery as snot, and tougher than hell to work on when venting. Ask around at your local building contractors for a cutout to play with. Window & door openings are cut out after panel installation.

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    We have a lot of this EPS roofing material being used in construction in our territory, combined with long span laminated beams 8"x8" and 8"x12". I've tried numerous times to get a piece of scrap for class and to play with on cutting and burning. The contractors say it is measured to the inch. There should not be any wasted material. The panels are expensive from what they tell me. Most of the roof panels are 5/8" osb with 12-16 inches of blue dense foam. It supposedly is tongue and grove. We had a worker fall through a uncompleted roof a year ago, luckily into a bedroom not few feet over into the living room. Most of the ceilings are cathedral 25-40 foot. I'd only vertical vent off a platform or Ladder if it can get in to it.
    YOU MUST visit the new construction sites as you see them. That is the only way we flagged some of the structures. It helps when one of our Volunteers is the owner of the construction companies.

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