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Roof Truss Design - unusual - Building Control

Discussion in 'Building Regulations and Planning Permission' started by Big_Jon, 24 Mar 2021.

  1. Big_Jon

    Big_Jon

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    Hello

    In the attached photo is a roof truss I think I need on my garage, that I wish to build. It's of a slight unconventional design it seems. I was just wondering if something like that will be passed by building control? I was also thinking that, would they a support to be added that is perpendicular to the left rafter (green beam) that runs to the joist (purple) as the "weatherboard" on the right (red block) is not really a structural member?

    The sizes if it helps that I think are correct and defined mostly by building regs are as follows:

    (red beam) - "Weather Board" - 38mm x 125mm
    (green beam) - Left Rafter - 47mm x 100mm
    (yellow beam) - Ridge Beam - 50mm x 150mm
    (blue beam) - Right Rafter - 47mm x 100mm
    (Peach beam) - Weather/Gutter Board - 38mm x 225mm
    (Purple beam) - Ceiling Joist - 145mm x 47mm
    (Darkish Green beam) - Wall Plate - 47mm x 100mm
    (Brown Block) - Cavity wall, drawn as block for illustration purposes

    Regards

    Jon
     

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  3. tony1851

    tony1851

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    A strange design?

    For one thing, depending on how wide the roof is, the rafter on the left will push out on the 38mm thick fascia board - you can't depend on the fixing between the fascia board and ceiling joist to keep the fascia board vertical.

    To ensure proper triangulation and therefore stability, the feet of the rafters should be tied together by the ceiling joist.
     
  4. ^woody^

    ^woody^

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    Here's something similar. This is either end of a truss

    20210325_090155.jpg
     
  5. jeds

    jeds

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    Truss manufacturers design to a standard computer programme, which won't allow the design if it doesn't work structurally. If it can be designed it should be accepted by BC.
     
  6. Big_Jon

    Big_Jon

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    So there is no other way to do it is what you are saying? No more braces you can add?

    So in other attached photos, I added a chock bit on the left rafter. But I don't think that will do as it still pushing out on the fascia board. Also included a more braced version. Don't know if that will do.

    Thanks for the photo, but I guess this relies on the rafter trying to push out against a wall, which you hope won't move.
     

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  7. ^woody^

    ^woody^

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    No. The truss rests on a wall at one end and a beam at the other. Its not pushing out.
     
  8. Big_Jon

    Big_Jon

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    I am only asking about this as I need to place a gutter on the slot on the left of the left rafter. Something similar to the drawing I was hoping. Just that I won't go through the wall. But then I don't know if that drawing can be conforming.
     

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