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  1. #1
    Join Date
    Mar 2007
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    Default Roof framing question

    OK, I am failing to get my brain around this roof framing.

    Framing is under the roof of the addition bumped out from the back of the house in the first picture. Pictures were taken by wading through 12" of blown in fiberglass and sticking the camera at arms length through a 8"x12" access hole hacked in the old roof in the main attic, it would be VERY difficult to get a head in there for direct observation.

    My question relates to the interrupted rafters to the right, I just can't visualize what's happening at this point. Clearly the load inboard of the junction with the hip rafters is being carried down to the former exterior wall of the main structure, but those "cut" rafter ends have to be supported, a single 2x12" seems small to act as a beam to carry the load,and in any case the rafter attachment seems insufficient to do so

    Or, maybe my visualization of the geometry is getting turned around by my limited vantage point?

    Can anyone point me to an illustration of this arrangement?

    - Thanks

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    Michael Thomas
    Paragon Property Services Inc., Chicago IL
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  2. #2
    Join Date
    Mar 2007
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    Default Re: Roof framing question

    Doesn't look right to me Michael. Single 2x4 installed flat as an unsupported purlin? Where's the collar ties, looks amateurish and I'd recommend a PE for a full evaluation of the roof support framing?

    Jerry McCarthy
    Building Code/ Construction Consultant

  3. #3
    Join Date
    Feb 2008
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    Default Re: Roof framing question

    Pictures 2 & 5 look the most informative to me but I'm still not entirely sure about the set-up.
    - Is that 2x4 wall supposed to be supporting the 2x12 intermediate ridge beam? I guess if they sit on top of a load b. wall and are nailed together it will work.
    - Are you thinking the short jack rafter runs are original rafters that they cut, then added the 2x12 and longer rafters for the bump out?
    - Or do you think Stanley ordered the rafters too short and added on.
    That sort of rafter set-up is common when doing a shed dormer bump out. The lack of proper support at either end of the 2x12 is worrisome. I would prefer to see an LVL. It isn't clear how long the span is. I agree with Jerry about the lack of collar ties or purlins. The set-up really lives the roof structure susceptible to movement during high winds or snow loads.

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  4. #4
    Join Date
    Mar 2007
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    Default Re: Roof framing question

    Quote Originally Posted by Markus Keller View Post
    - Are you thinking the short jack rafter runs are original rafters that they cut, then added the 2x12 and longer rafters for the bump out? - Or do you think Stanley ordered the rafters too short and added on...
    Keep in mind those pics shot by sticking the camera through the small opening between the roofs, I did not directly observe any of that.

    And now, looking at the pics again after improving them in Photoshop, I'm thinking perhaps that's *blocking*, the rafters *are* continuous, and that structure at the rear is just supporting the hip rafters, and that "purlin" is just a nailer.

    ----------

    Later....

    Nope. Cut. I don't see *any nailing* except one toe-nail through the bottom, are they just resting on the purlin?

    Sure looks like.

    My guess is that the "purlin" was actually a temp support, the framers left for the day, and the sheathing went on the next morning without the rafters having been attached.

    Anyway, that's my story and I'm sticking to it unless someone here comes along and tells me I've got it ALL wrong, preferably *before* I have to tell the client that the last time I saw this construction technique I was nine, and we were playing Pick-Up-Sticks.

    Meanwhile, framing contractor, or SE?

    ---------

    It will be a *big* mess to get in there if that has to be improved, likely they will to remove the attic furnace and a considerable amount of duct to get in from the interior, might be easier to strip a section of roof and go that way.

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    Last edited by Michael Thomas; 05-15-2008 at 04:50 PM.
    Michael Thomas
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  5. #5
    Mark c Jones's Avatar
    Mark c Jones Guest

    Default Re: Roof framing question

    I would recommend further evaluation.

    Mark

    Allmark Home Inspections Inc.
    Allmark Home Inspections Illinois


  6. #6

    Default Re: Roof framing question

    I would also have a concern as to the header size above those windows. Possible just top plates?

    I would also like to see a detail of the header over the patio doors, they look like an upgrade install? with no shear this would be a failure concern.

    Rolland Pruner
    Livermore, Calif


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