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Thread: Sagging Roof

  1. #1
    Join Date
    Nov 2010
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    1

    Default Sagging Roof

    Hello Experts,

    In my house, some parts of the roof appears to be sagging. I have brought in a few roofers to look into it and they seem to think that it is because some of the panels, which are in good shape, do not have adequate support and/or bad nailing job. And all of them suggested that I change the entire roof, which would cost around $15K to $18K. I was wondering if there is any inexpensive solution to this problem. Also, what kind of skilled professionals would be appropriate for this job? Please help.

  2. #2
    Join Date
    Aug 2007
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    The Great White North
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    Default Re: Sagging Roof

    Quote Originally Posted by andy_c View Post
    Hello Experts,

    In my house, some parts of the roof appears to be sagging. I have brought in a few roofers to look into it and they seem to think that it is because some of the panels, which are in good shape, do not have adequate support and/or bad nailing job. And all of them suggested that I change the entire roof, which would cost around $15K to $18K. I was wondering if there is any inexpensive solution to this problem. Also, what kind of skilled professionals would be appropriate for this job? Please help.
    Without more detail about the construction of the roof or what you mean by sagging it's difficult to say for sure what can be done.

    However, based on the mention of "panels" I'm guessing your roof is constructed with sheathing ( common 4x8 sheets of OSB or plywood ) over rafters.

    If this is the case ---for many areas minimum code allows 24 inch center spacing between rafters with some areas allowing ( at one time ) 3/8 inch thick plywood or 7/16 inch OSB sheathing with " H " clips located at the unsupported seams where no blocking is used .
    Since it is minimum code it's also cheaper for the builder.

    Though that has changed in may areas to 1/2 inch sheathing with " H " clips.

    What all this means is you will notice a wavy roof ( sagging between the rafters ).
    Unfortunately it's next to impossible to try and remove the sagging of the sheathing since heat , weight , and gravity has now formed the sheathing to a new shape.
    Most often this doesn't pose any structural issues but more of a cosmetic one.

    So, removing the shingles down to the existing roof deck and ensuring there is no water damage -- lay new sheathing --- would be one of the simplest methods.

    Any roofing company can do this.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  3. #3
    Join Date
    Mar 2008
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    nova scotia, canada
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    Default Re: Sagging Roof

    just as canuk said, nail the sheathing to the trusses or rafters and not just the old osb or plywood, it will stiffen up the roof more too, make sure not to break sheets on the same rafter as the old sheets
    fire up the saw and make some dust

  4. #4
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    Default Re: Sagging Roof

    Quote Originally Posted by jkirk View Post
    just as canuk said, nail the sheathing to the trusses or rafters and not just the old osb or plywood, it will stiffen up the roof more too, make sure not to break sheets on the same rafter as the old sheets
    good point Mr.Kirk
    "" an ounce of perception -- a pound of obscure "
    - Rush

  5. #5
    Join Date
    Dec 2007
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    MN
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    Default Re: Sagging Roof

    Canuk & jkirk rock. Great stuff guys.

  6. #6
    Join Date
    Mar 2009
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    66

    Default Re: Sagging Roof

    I have an idea that I used on a sister-n-law's home.It came from an old retired carpenter.We ran what is known as a stiff back,the length of the sagging area of the roof.Now I am talking up inside the attic mind you. Each rafter we cut a 1 inch wedge half way through each rafter.Then jacked up each rafter taking as much of the bow out as was safely possible.While still supported by the jack we screwed a 2x6,12 foot long in this case against the existing rafter.We then jacked up on each additional rafter,repeating the same steps.In this case we had plenty of room to work in the attic.That was six years ago and it is still holding fine.Mind you though not all of the sag was removed,but it was a noticeably improvement.Much less costly than removing the roof to make the repair.

  7. #7
    Join Date
    Mar 2009
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    1,387

    Default Re: Sagging Roof

    Howdy consider having a general contractor out to inspect the roof. With out any more information it is not easy to direct you it could be the roof is expanding, is it a rafter system ? Or snow damage or lots of other things that the roofers may not have knowledge about...
    Any an all of my comments are just my opinion and not to be confused with facts.

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