Joist depth for timber staging

Discussion in 'Carpenters' Talk' started by ShabbaPlanks, Feb 22, 2019.

  1. ShabbaPlanks

    ShabbaPlanks Member

    Hello, I need to bridge a roof which is 5.5 mtrs wide. I have cuplock scaffold to go either side and enough poles to put a hand rail across the area to be bridged. Rather than buy more scaffold to bridge the roof I thought I could use timber staging, I can reuse the wood for some long planters once the job is done :)
    Having looked at a few joist span tables 5532mm would be C24 72mm x 220mm. I am wondering if I could get away with less depth or width, as this staging is only to carry me, a few roof tiles, and some fascia. I dont mind a bit of bounce. Platform will be 1.2 mtrs wide with 22mm ply, so three joists at 600mm. Would you be happy to walk out on less than the span table recommend?
    Any input appreciated
     
  2. stevie22

    stevie22 Screwfix Select

    I would walk on that (gently first time) but do pick decent timbers. TRADA tables are based a 0.003xspan to a 14mm maximum deflection for floor joists so you have loads of strength in hand.

    1200 seems very wide for what you want
     
  3. chippie244

    chippie244 Super Member

    Ply top and bottom and it will be sound.
     
    ShabbaPlanks likes this.
  4. DIY womble

    DIY womble Well-Known Member

    Prop a beam half way
     
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  5. ShabbaPlanks

    ShabbaPlanks Member

    Cheers I might give that a go. Terrified of breaking a roof tile or two as they dont make them anymore, otherwise I might just chance walking on the roof.
     
  6. ShabbaPlanks

    ShabbaPlanks Member

    Less than 600mm is to narrow for me, over 600mm means three joists, at that point I may as well use the full width of sheet ply and not have to make any cuts. Plus I can put the full sheets to better use after.
     
  7. ShabbaPlanks

    ShabbaPlanks Member

    Will the ply on the bottom make much of a differance Chippie, I have never had to build something like this before and really want to keep cost down as much as possible. Idealy I was hoping to use lesser timbers than those quoted in the span guide. Dammit, just realised those timber spans are listed at 450 centres :(
     
  8. chippie244

    chippie244 Super Member

    It makes it into a torsion box, very stiff.
     
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  9. CGN

    CGN Screwfix Select

    Have you checked out the price of coffins recently?
     
    Last edited: Feb 23, 2019
    ShabbaPlanks likes this.
  10. ShabbaPlanks

    ShabbaPlanks Member

    Thank you
     
  11. ShabbaPlanks

    ShabbaPlanks Member

    Point taken, I realised I was subconsiously looking for someone to say, yeh it'll be ok. I have a month or so to put something together. If I reduce the joists it will be because I have them propped mid span on some bearers to spread the load. Thanks for pointing me straight
     
    CGN likes this.
  12. CGN

    CGN Screwfix Select

    I’m not a great fan of working at heights. I can do it, it’s just not my everyday work, so when I do, I appreciate a good solid scaffold with hand railing etc. The last roofing job I worked on was helping re-roof a 3 storey terrace and that’s a fair old height to fall from.
     
  13. Jord86

    Jord86 Screwfix Select


    Unless I'm missing something, buy the long lengths of timber you need and double them up, eg 9x2's turn into 9x4's.
     
  14. stevie22

    stevie22 Screwfix Select

    Chippie's comment about box beam is spot on but I suspect you will have to assemble insitu due to weight so won't be possible.

    Personally I would stick to 600 wide on 3 timbers: nog then together metre or so and it won't go anywhere. Wider platform will make you more inclined to put loads of gear on it
     

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