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Part flat part pitch roof for wraparound extension - beam needed?

Discussion in 'Building' started by Tgeorge, 3 Jul 2021.

  1. Tgeorge

    Tgeorge

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    We are planning a wraparound extension with a side width of 3.3m and a rear depth of 4.5m and an overall width of 11m.

    Due to various constraints including neighbours, the highest part of the rear extension cannot go above 3.35m from the ground floor level so we planned a part flat and part pitch roof design to make it all work the way we like and to satisfy the other constraints.

    This means that the flat roof section will be at a height of 3.44m. The pitched roof will have a 17.5-degree pitch with large Velux windows.

    Being a novice, I am trying to figure out what the flat section of the roof will rest on at the end where it meets the side extension roof - where I have circled in red.

    I want to avoid using columns in the extension if I can. Would I need some sort of fancy steel beam arrangement or is this quite easy and can be achieved with just timber?

    Any suggestion will be very useful as I want to avoid expensive structural engineering work and columns inside the extension but of course, if it has to be done then I will accept it

    Note that the red line in the side extension is a wall.


    roof-design.jpg
     
  2. tony1851

    tony1851

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    Consider a cranked beam, welded at 17.5° Something like a 152 x 152 should fit between the rafters on the side roof slope.
     
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  4. freddiemercurystwin

    freddiemercurystwin

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    Vaulted ceilings? Otherwise ordinary trusses would work.
     
  5. Tgeorge

    Tgeorge

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    Yes vaulted with velux windows. Thanks
     
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  7. Tgeorge

    Tgeorge

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    Many thanks. Looked that up and looks like just the thing. Guess we would need only one of them at the side where there is no wall for the flat part to rest.
    Is a cranked beam easy enough for a structural engineer to specify?
     
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