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Roof joist installation

Discussion in 'Roofing and Guttering' started by Gauss, 7 Sep 2019.

  1. Gauss

    Gauss

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    Hi - My builder is in the process of finishing off my 8m by 9m outbuilding and he’s installed the roof joists as attached.

    Does this look right? Any advise or thoughts are appreciated.

    TIA.
     

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  2. Bonni

    Bonni

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    Where's the wallplate on the steel? Where's the structural engineer's plans? You would normally fix a timber wallplate to the steel and then fix the top of the timbers to the wallplate.

    Are there any horizontal timbers on the structural plans just below the steel? If so, the timbers sit side by side at the top so horizontal timbers will now not fit unless you pack out by the thickness of the timbers. I normally bolt mine together with dog washers in between (teethed washers).
     
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  3. catlad

    catlad

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    It may be my eyes but that beam looks slim for 8mts
    as per Bonni the beam has been drilled for timber to be bolted to it? He might line the rafters up before he continues.
     
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  4. Gauss

    Gauss

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    Rafters are interlaced and are screwed together? They then placed wood between them and screwed along too.

    Beam is 150 x 150
     
  5. ^woody^

    ^woody^

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    It could be nit-picked, but it looks like a nice job.
     
  6. paulrockliffe

    paulrockliffe

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    If it's an outbuilding then that method may be preferable as it'll let you get a block and tackle running along the bottom flange of the beam.
     
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  7. bobasd

    bobasd

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    just saying, not criticising - its not a sloppy job so things may have been done for a purpose?

    looks like the angle of the roof comes out at 15 degrees - kind of low.
    as mentioned above, collar ties would help - so would Simpson angle brackets tieing the rafters at the wall plates - cant tell if the rafters are birds mouthed?
    and allowing the rafters to run past the RSJ before snipping off the corners (to be in plane) would have allowed more rafter meat to screw to.
     
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  8. noseall

    noseall

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    I think you need to swot up on your trig mate. 18 degrees at least.(y)
     
  9. bobasd

    bobasd

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    Thanks, your right, its 18.43 degrees.
     
  10. catlad

    catlad

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    I've just noticed how little those rafters overlap at the ridge
    That's a poor detail.
     
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  11. Leofric

    Leofric

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    Some photos were posted on here recently showing some neat examples of dual pitched roofs with one example using a steel ridge beam and another using a timber ridge beam. These had the basics of good construction with the rafters in line and birdsmouthed over a timber plate on the top of the steel beam and collar ties as others have mentioned under the ridge beam. The rafters at the apex also need tying together.
     
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  12. noseall

    noseall

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    Thanks for the compliment....
     
  13. catlad

    catlad

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    I take it the apprentice cut the collar ties in the first picture
    being that short!
     
  14. noseall

    noseall

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    Lol.

    They aren't collars in the true sense although they will act as such and add stiffening. The roof was designed without collars. They are more cosmetic i.e. there to cradle the plasterboard hence the spindly 3" x 2". You are right though that 'my right arm' did a lot of the work on that job. It was his 'test', being as it's my connie that was being bashed about. The snots he left on the back of the blockwork, almost spanned the entire cavity.:eek:

    :ROFLMAO::ROFLMAO::ROFLMAO:
     
  15. Leofric

    Leofric

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    Whatever you want to call them the horizontal timbers under the ridge beam basically fasten the rafters together and are best taken across the full width of the rafters (with splay cut ends of course )
     
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