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  1. #1
    Join Date
    Dec 2008
    Location
    Erwin, TN
    Posts
    291

    Default Missing ridge beam and or ridge board

    This newer carport roof rafters had no ridge beam or ridge board installed. Would this be acceptable, is there any reason for concern ??DSCN9288.JPGDSCN9287.JPGDSCN9286.JPG

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  2. #2
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    27,471

    Default Re: Missing ridge beam and or ridge board

    As i understand it, all a ridge board does is allow for a minor offset of the rafters with each other. The dead load and live load of each side of the roof is transferred down to the bearing plate the rafters are set on, and transfer loads at the top of the rafters to the other rafters on the opposite side.

    No ridge board means the tops of the rafters must be aligned with each other, no offset allowed - and the rafters in your photos look aligned with each other.

    A ridge beam is a different component as it is supported at its ends, and the ridge beam then supports the top of the rafters, transferring the loads to the ridge beam, then to the ends of the ridge beam and the support of the ridge beam.

    No ridge beam (i.e., using a ridge board or just rafter-to-rafter) requires collar ties (or the ceiling joists attached to the botton of the rafters to serve as rafter ties) to keep the rafters from spreading apart and spreading the walls apart on which the rafters are bearing.

    However, with or without a ridge board or ridge beam, unless hangers are used on a ridge beam, the concern becomes the match of the cut at the rafters ends as that is where the load meets and transfers ... and if the cut ends don't match (the cut ends in your photos don't match), then the load bearing area is reduced to the point contact of what is actually touching. With contact only at the points of the cut ends - the load can only be transferred through that point contact.

    This can, likely will, lead to splitting the rafters, the split starting at the top of the rafters and going down. A split rafter is effectively no longer the same size it was, depending on where the split is, and how long the split eventually gets.

    There may be an easy fix: plywood gussets on each side of each rafter-to-rafter meeting point at the ridge. Let a structural engineer state how thick plywood to use, how large the gussets need to be, size and spacing of the nails ... then after the work is done, the engineer needs to provide a letter (signed and sealed) stating that the repairs were done in accordance with the engineering design.

    Having an engineer's letter stating 'do this' is useless unless there is also an engineer's letter stating 'yep, they did that'.

    (I typed this on my phone, I'll read it on the computer later and make typo changes as needed.)

    Last edited by Jerry Peck; 10-07-2020 at 11:52 AM. Reason: typos
    Jerry Peck
    Construction Litigation Consultant ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

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