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Thread: ALMOST FLAT ROOF QUESTION/HELP

  1. #1
    Senior Member
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    Sep 2002
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    Western, Massachusetts
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    243

    ALMOST FLAT ROOF QUESTION/HELP

    Hi guys.

    Still working on the porch...a lot of progress has been made, roof is now finally on.

    The roof is a almost flat roof, 1 foot of rise in 12 feet, so I went with a rolled roof material with liberal amounts of roofing cement in between layers, and in addition I covered the entire roof first with ice/water shield.

    I might be beating this to death, but I am not happy with the way the roof looks and don't have a lot of hope that I have done everything I could to prevent leaking in the future.

    My question is, after I have installed the rolled roofing, for whatever reason, perhaps my inexperience or perhaps because thats the way its supposed to look, the rolled roof layers don't lay completely flat on top of each other, so I am worried about leaking.

    Now I am wondering if I should nail all of the exposed "seams" and put some sort of "overcoat" of tar/cement on top of all the nails to prevent water from being driven up under the layers.

    The roof can't really be seen from anywhere, except when you are working on it, so I am not to particular about how it looks...just don't want any nasty leaks this winter.

    Question is, is nail all the seams and the putting another layer of tar/cement along the seams a good thing to do, or am I asking for trouble?

    If I had to do it all over (and I may have to if it leaks), I think I should have gone with some sort of hi-tech membrane systme or else a hot mopped tar roof...

    Suggestions on where to go from here? [img]/forums/images/icons/confused.gif[/img]

  2. #2
    Senior Member
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    Sep 2002
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    midwest
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    Re: ALMOST FLAT ROOF QUESTION/HELP

    I think you will be okay with how you have done it. I wouldn't put nails in with tar on them, unless there was a layer of roofing over the tar. IMO.

    I had a flat roof over my 24' x 24' garage that had a 3" in 12' slope, and had half lap (rolled roofing designed to be lapped half way up) on it for about the first 18 years. No problems. Now granted, I am told the half lap we had available in 1968 was a far cry better than what we can purchase now. But it lasted a long time.

    I put it down with (memory may be a bit off) about 16" to the weather. I nailed just under the lap, and tarred the nails good. Then the next lap went on to just cover the nails. I had no problem with leaks nor with wind blowing up the tarred lap joint.

    After 18 years, I had it re-roofed with the rubber membrane. I was very pleased with that system. Now I have an addition on top of the garage, and am using the rubber membrane in strips to cover my outdoor dry storage of firewood. I think the rubber is the only way to go. But still think you are okay with your roof.

  3. #3
    Senior Member
    Join Date
    Sep 2002
    Location
    Brookshire, Texas
    Posts
    191

    Re: ALMOST FLAT ROOF QUESTION/HELP

    Sounds like you made a built-up roofing system - they do tend to look lumpy. In many cases, they are covered with a gravel topping to protect the top surface as well as for a better look. Problem is that if you walk on the gravel, it can eventually penetrate into the roofing.
    My preference is to specify EDPM roofing wherever possible - that's the smooth rubber/butyl sheeting that you see in many applications. It can either be mechanically fastened or fully adhered to the underlayment boards, with the flashing material at penetrations or edges of the same material and glued to the base sheeting. All seams are overlapped and glued.
    I hate to say this, but if you considered re-doing the roof, first install the rigid board insulation - these also come tapered so you create a slope too - fastened to the roof framing. You would need to strip off the top layers of roofing you have applied. The roof membrane is applied directly over the board insulation. I would be concerned about nailing through the seams as you mentioned and covering it with roof pitch, as this will deteriorate and leak over time.
    You had also mentioned apprearance - the EDPM will look much cleaner installed.
    Nick

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