Decking structure - help please

Discussion in 'Getting Started FAQ' started by highlander7, Aug 3, 2018.

  1. highlander7

    highlander7 New Member

    I’m planning to build a raised deck attached to the back of the house and wondered if anyone could help with a few queries please ? Planned spec and queries as follows:


    Height from ground varies from approx 0.7m to 1.0m

    I have planning permission

    Width approx 4.9m x depth 2.5m

    Wall plate 4.9m using 150mm x 47mm joist (will need to split as over 4.8m in length unless I could bolt an additional 2.5m joist to the side)

    Posts 100mm x 100mm set at approx 1,250mm centres, ie two rows of five posts (plus wall plate / ledger)

    Joists 150mm x 47mm attached to posts round perimeter

    Joists approx 2.5m x 150mm x 47mm set at 400mm centres

    Supporting double joists running under 4.9m length to support middle of 2.5m joists

    Composite deck board approx 145mm x 25mm

    Stainless steel handrails and glass panels


    Queries:

    1 Fixing joists to posts: could I use screwfix turbo coach screws and if so, would M12 x 140mm be correct or M10 x 100mm or should I stick with coach bolts M12 x 180mm ?

    2 Fixing joists to wall plate: I’m not sure here but am thinking of using Sabrefix mini hangers 50mm x 65mm – is that correct or should I use a different hanger (don’t want part of it to go over the top of the wall plate) ?

    3 Fixing joists to wall plate: how best to attach the end joists as I can’t really use a joist hanger – do I just use two screws either side at an angle through the joist and into the wall plate ?

    4 Fixing the wall plate to the wall: stainless steel washers to pack it out about 10mm from the wall but not sure what to use to bolt it to the wall, how big it should be and how long – something like Rawlplug Rawlok Sleeve Anchors Yellow-Passivated 12 x 130mm M10 or Easyfix Sleeve Anchor 12 x 130mm M12 10 Pack or something else ??


    Many thanks
     
  2. Wayners

    Wayners Active Member

    I don't like using metal hangers outside because it rusts and looks naff. Wooden cut joints. Bolts. Resin for threaded bolts to masonry. Any screws that will do the job for the rest of it. Not really my area of knowledge just pitching in as you never got an answer.
     
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  3. Isitreally

    Isitreally Well-Known Member


    Most hanger are galvanized so no rust.
     
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  4. Wayners

    Wayners Active Member

    Yeah. Always seem to be get a bit though after a time. I'm more the old fashioned way of joining timber but I guess it's not the fasted or easiest way.
     
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  5. highlander7

    highlander7 New Member

    Wayners, Isitreally - thanks for replying :)
     
  6. Isitreally

    Isitreally Well-Known Member

    Bolting plate to wall use galvanised square plate washers as spacers 10mm or so as you said.

    Use Thunder bolts to fix to brickwork, bolt length 75mm longer than timber and spacers.

    Hangers for joists is fine.

    Coach bolts for fixing to posts.

    This is what i would do.
     
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  7. highlander7

    highlander7 New Member

    Thanks for that. Interesting - I've never tried self tapping threaded bolts directly into masonry before as I've generally used Rawlplug Sleeve Anchors / similar
     

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