1. Visiting from the US? Why not try DIYnot.US instead? Click here to continue to DIYnot.US.
    Dismiss Notice

Span tables for deep joists

Discussion in 'Building Regulations and Planning Permission' started by garyo, 17 Jan 2019.

  1. Leofric

    Leofric

    Joined:
    9 Nov 2018
    Messages:
    1,882
    Thanks Received:
    172
    Country:
    United Kingdom
    The timber and steel joists are Easi-joist open web system by Wolf Systems. They allow services to pass through as big as 110mm soil pipes. No need for steel beams . Just a thought.
     
    • Like Like x 1
  2. Sponsored Links
  3. garyo

    garyo

    Joined:
    11 Apr 2006
    Messages:
    1,894
    Thanks Received:
    177
    Location:
    Berkshire
    Country:
    United Kingdom
    I'm starting to like the look of this. In the garage at the bottom of the drawing the longest span is only 1.8M so I could get away with 150mm @ 400c/c as Tony says. In the room at the top the spans are wider with a single steel.

    I think the way to go might be to go to a single steel in the garage too and then standardise the joist depth to 195mm @ 400c/c across the whole extension, and then the joist depth will also match my roof rafters which will add convenience.

    [​IMG]
     
    Last edited: 18 Jan 2019
  4. Leofric

    Leofric

    Joined:
    9 Nov 2018
    Messages:
    1,882
    Thanks Received:
    172
    Country:
    United Kingdom
    Can't be sure but it looks as though one of those proposed steel beams might be bearing on to a lintel over an opening !
    I wonder how the cost of traditional timber joists and 3 new steel beams would compare with doing it in the Easi-joist system but I don't suppose we will find out.
    Regards
     
  5. garyo

    garyo

    Joined:
    11 Apr 2006
    Messages:
    1,894
    Thanks Received:
    177
    Location:
    Berkshire
    Country:
    United Kingdom
    Sorry that's just the positioning of my section plane that's just caught a bit of the upstairs layout, so no issue.

    I'll take a look but the last time I asked for a quote from JJ it didn't add up for me given the weather exposure risk and the general nervousness you get using a non standard system.
     
  6. ^woody^

    ^woody^

    Joined:
    3 Sep 2006
    Messages:
    27,165
    Thanks Received:
    3,399
    Location:
    West Mids
    Country:
    United Kingdom
    Jeez, just put a trimmer across where the longer joists would be. :confused:
     
  7. Sponsored Links
  8. Leofric

    Leofric

    Joined:
    9 Nov 2018
    Messages:
    1,882
    Thanks Received:
    172
    Country:
    United Kingdom
    As in Post 7 and as Woody says the double trimmers would be the usual way of doing it. I should have posted this earlier but just realised I have a copy of the old Approved Document A , and according to table 1 for class SC3 timber joists at 400mm crs (dead load more than 0.25 but not more than
    0.50 kN/m2 ) you can span 4.91m with 220 x 63mm size joists. So I think that answers your original query and you wouldn't need to use any steelwork.
     
  9. garyo

    garyo

    Joined:
    11 Apr 2006
    Messages:
    1,894
    Thanks Received:
    177
    Location:
    Berkshire
    Country:
    United Kingdom
    Is there a point when the trim span is too much? At what point do sistered trimmers need to be tripled?
     
  10. noseall

    noseall

    Joined:
    2 Feb 2006
    Messages:
    35,432
    Thanks Received:
    2,233
    Location:
    Staffordshire
    Country:
    United Kingdom
    We used Posi-Joists to span our current 7.6m extension, coming out at a mere 450mm deep!:eek:
     
  11. Leofric

    Leofric

    Joined:
    9 Nov 2018
    Messages:
    1,882
    Thanks Received:
    172
    Country:
    United Kingdom
    'Bolt trimmer using 51mm diameter double-sided round toothed plate connectors and M12, grade 4.6 bolts at 600mm centres.' - double joists as trimmers should be bolted together. There are Building Control guidance tables for trimmer joists/beams and trimming joists. Depends if trimmers are also supporting partitions above but usually joists are tripled when they are 'trimming joists' supporting a 'trimmer joist/beam ' in my experience ,but it depends on spans and loadings.
    Double joists as trimmer should be ok across your 2872 opening but I can't prove that.
     
  12. DIYnot Local

    DIYnot Local

    Joined:
    3 Sep 2019
    Country:
    United Kingdom

    If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

    Select the supplier or trade you require, enter your location to begin your search.


    Are you a trade or supplier? You can create your listing free at DIYnot Local

     
Sponsored Links
Loading...

Share This Page