Hanging heavy bag from Garage roof

Discussion in 'General DIY' started by withers, 5 Oct 2021.

  1. JP_

    JP_

    Joined:
    17 May 2012
    Messages:
    8,490
    Thanks Received:
    493
    Country:
    United Kingdom
    yes, that is what I meant - you said it better!
     
  2. Sponsored Links
  3. JP_

    JP_

    Joined:
    17 May 2012
    Messages:
    8,490
    Thanks Received:
    493
    Country:
    United Kingdom
    Yes, long joists, like the bottom ones there now, but it will be much bigger and not support anything above, just for the bag. I don't know how to calculate the size, so just go big!
     
    • Like Like x 1
  4. JobAndKnock

    JobAndKnock

    Joined:
    30 Sep 2011
    Messages:
    6,850
    Thanks Received:
    1,484
    Location:
    Lancashire
    Country:
    United Kingdom
    A quote from a technical paper (called "The Seven Deadly Sins of Trussed Rafter Construction") on Fink truss roofs: "Typically the bottom chord of a truss is designed for a superimposed load of 0.25 kN/m2 which the author often refers to as empty cardboard boxes loading."

    So whilst the top of a Fink truss frame is designed specifically to carry the load imposed by the roof cladding, snow and wind, the bottom chord is designed to carry only a thin skin of plasterboard and little more. Not surprising when you consider that the bottom chords on this roof are 75 x 38mm (3 x 1.5in) on about a 4.1m (13.4ft) span (based on those blocks being 340mm long blocks)

    There are exceptions to this, where the builder has specified that the bottom chord be capable of supporting a load, but that does need to be specified at time of manufacture
     
    Last edited: 6 Oct 2021
  5. JP_

    JP_

    Joined:
    17 May 2012
    Messages:
    8,490
    Thanks Received:
    493
    Country:
    United Kingdom
    Makes sense - the bottom bit is only really there to stop the top bits going sideways.
    I had my extension done with trusses (7m wide, 7m long) and the smaller builder did walk around on them, but said it was still a bit hairy!
    They ended up putting in a solid internal wall so the who thing was also supported on that - as I asked them to board it for storage.
    They don't make houses like they used to!
     
  6. JobAndKnock

    JobAndKnock

    Joined:
    30 Sep 2011
    Messages:
    6,850
    Thanks Received:
    1,484
    Location:
    Lancashire
    Country:
    United Kingdom
    If you ever see a truck delivering them you'll maybe notice that they are invariably carried apex downwards because as one SE put it "Sort of like an eggshell they are stronger in one direction". The preference is also to crane them in place these days rather than manually handling (at least where I've worked) as doing that means there is less chance of damaging the all important bottom chord or the nailer plates

    trusses never handle.jpg
     
    Last edited: 6 Oct 2021
  7. Sponsored Links
  8. Dereekoo

    Dereekoo

    Joined:
    2 Jan 2012
    Messages:
    327
    Thanks Received:
    49
    Location:
    Nottinghamshire
    Country:
    United Kingdom
    I'm thinking those blocks are 440 long so span nearer 5m?
     
  9. withers

    withers

    Joined:
    5 Oct 2021
    Messages:
    26
    Thanks Received:
    0
    Country:
    United Kingdom

    Now I think I know what you both mean, thick heavy duty joists NOT rafters fixed to the top of the piece of wood resting across the top of the wall above the window running in parallel to current rafters.

    And if the joists do not fit, use joist hangers attached to the wall

    The fixing holding up the bag is fixed to the joists hanging down, any impact from the bag is sent into the joists and at most directly into the wall and not the roof structure

    I have created a diagram of how I imagine it, this is a view if you were looking at it from the ceiling looking down, let me know if it makes sense or not.

    [​IMG]
     
  10. withers

    withers

    Joined:
    5 Oct 2021
    Messages:
    26
    Thanks Received:
    0
    Country:
    United Kingdom
    If you are referring to the rafters in my garage yes the garage is just shy of 6M long (back of garage to garage door)

    Just to add they appear to be extended further down using those metal plates that hold the rafters together
     
  11. Dereekoo

    Dereekoo

    Joined:
    2 Jan 2012
    Messages:
    327
    Thanks Received:
    49
    Location:
    Nottinghamshire
    Country:
    United Kingdom
    Completey disorientated, what is width of garage?
     
  12. withers

    withers

    Joined:
    5 Oct 2021
    Messages:
    26
    Thanks Received:
    0
    Country:
    United Kingdom
    Actually just got floor plans up the garage 2.59m wide by 5.39m long

    So the rafters are very likely 5m total.
     
Loading...

Share This Page