decking structure

Discussion in 'Carpenters' Talk' started by marko65, May 10, 2009.

  1. marko65

    marko65 New Member

    Currently installing decking - have fitted ledger on house wall and will hang joists from this using joist hangers - the deck is 4.5m going away from the house - where should I fix my next beam (using 4x4 posts concreted in) to support the joists - will one at 2.25 and then the outer one be adequate?
     
  2. chippie244

    chippie244 Super Member

    If you are using 7"x2" at 400mm centres, a good imp/metric mix :), it will span about 4M so what you are suggesting is more than adequate.
     
  3. marko65

    marko65 New Member

    I'm using 6" x 2" joists @ 400mm centres - so looks like I should be O.K. - any tips on concreting in 4x4 posts to avoid them rotting too quickly?
     
  4. chippie244

    chippie244 Super Member

    A properly pressure treated timber should last 20 years.
     
  5. cosworth

    cosworth New Member

    will a 7x2 really span 4 metres???

    span in ft divide by 2 then add 2 inches.

    so for instance.... 10 feet, divide the 10 by 2=5 then add 2 inches= 7x2.

    rough rule of thumb for span calcs.
     
  6. cosworth

    cosworth New Member

    so a 6x2 will span 8ft at 400 centres max.
     
  7. chippie244

    chippie244 Super Member

    And 8' in metric is........
     
  8. cosworth

    cosworth New Member

    2438mm just checked on the tape;)
     
  9. cosworth

    cosworth New Member

    and im terrible for mixing imperial and metric in the same sentence. its stupid i know but i just cant be bothered to type or say a joist of 175mmx50mm. far to tyred for that.
     
  10. cosworth

    cosworth New Member

    haha. too tired to spell tired:)
     
  11. chippie244

    chippie244 Super Member

    His span is 2250mm so well within limits.
    I generally call 8' 2440mm although I think the correct no is 2439.
    I said ABOUT 4M for a 7"x2" and you said ROUGHLY 10' which is 3048mm.
    I'm sure some one will come up with the Trada span tables

    :)
     
  12. cosworth

    cosworth New Member

    ok no probs mate. wasnt being picky just didnt read you clear. :)
     
  13. chippie244

    chippie244 Super Member

    I'm the same, lengths in metres, timber dimensions in imperial ie 4M of 3"x1". Sheet length and width in imp but thickness in mm ie 18mm 8'x4'. Which ever is easiest although I think in imp all my drawings are in mm.
     
  14. marko65

    marko65 New Member

    Thanks for your help - one last question - have noticed that some of the timber (6x2) delivered is stamped c16 and some c24 - is there any significant difference?
     
  15. chippie244

    chippie244 Super Member

  16. chippie244

    chippie244 Super Member

    Easy answer, not really.
     
  17. marko65

    marko65 New Member

    clever - thanks again - no more for now
     
  18. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    If the posts(ground level) are to be covered(they will be under the decking), build the concrete to a 'pyramid' round the post and have the concrete finish above ground. That'll help stop pooling.


    Mr. HandyAndy - Really
     
  19. marko65

    marko65 New Member

    I put in first post today and have done so - any advice on the number of posts to support a double centre beam of 4.8 metre length.
     
  20. chippie244

    chippie244 Super Member

    Every 4' should be ample ;)
     

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