Joists on top of existing wall

Discussion in 'Builders' Talk' started by NTHigh, Jul 4, 2023.

  1. NTHigh

    NTHigh New Member

    Hi I am upgrading the ceiling joists in my bungalow. They currently sit unattached on top of the wall plate i.e. there are no joist hangers and they are on top of the wall plate. Previously they only supported the ceiling plasterboard. I want a structural floor. I plan to use 150 by 47 C24 timber at 400 centres but cannot figure out the correct way to attach the new timbers.
    Joist hangers would reduce the ceiling height. Is there an alternative ?
    Here is photo of the current joists sitting on the timber wall plate

    Attached Files:

    Last edited: Jul 4, 2023
  2. Mark DM

    Mark DM Screwfix Select

    truss clips or cleats?. Or as used to do and fix through the sides and into the plate. Have you had the new floor detail calculated and specified as fixing detail should show on drawing . Span, loading etc
    NTHigh likes this.
  3. NTHigh

    NTHigh New Member

    Thanks I don’t have that detail on the drawing just the timber calculations.
  4. stevie22

    stevie22 Screwfix Select

    They would normally just sit on the plate but with a plywood pack to just lift them clear of the existing ceiling.

    You have no ceiling to load so just sit them. You may need to clip the top corner to clear the tiles and get full bearing.

    6s are pretty small for loft floors!
  5. Mark DM

    Mark DM Screwfix Select

    Ref the spec i refered to, I also was wondering about the 150 x 47 you are planning to use.
  6. qwas123

    qwas123 Screwfix Select

    Until you post the joist span, and the expected load then its foolish to guess the joist section size.
    There are joist calculation tables on google.
    Your existing joist tails are correctly skew nailed into the wall plate - nail heads can be seen - they should also have been fixed to the rafter tails.
    Use screws for fixing the new joist tails.
  7. NTHigh

    NTHigh New Member

    Thanks. The sown is only 2.8m. The tables I checked confirmed the joists I had been quoted. Thanks for the suggestions.

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