Joist advice ...

Discussion in 'Carpenters' Talk' started by gb2021, Oct 2, 2021.

  1. gb2021

    gb2021 New Member

    Hi. Hope this makes sense. I apologise in advance ... joists (1).jpg it's a little difficult to explain! Attached is a picture of the joists in the bedroom above. In the living room below, the joists are exposed at the bottom i.e they are designed to look like old beams. with the plasterboard running on battens between. I thought they were stuck on "faux" beams which could be removed but they are actually the bottom edge of the joist. I have never seen this before. I have cut a section out as in pic. I want to remove the "exposed" beam. My question. Can I just cut the edge off and leave 150mm joist without affecting integrity/strength of joist? And second ... the cut probably won't be exactly even ... will this be a total headache when plaster
    boarding over?
    I hope this is at least a little clear... thanks G
     
  2. Severntrent

    Severntrent Screwfix Select

    So you want to reduce 200 beams to150 beams?. In all probability, unless the beams were oversized in the 1st place, the structural strength and/or deflection capabilities will be reduced to unacceptable limits.
     
    woodbutcherbower and Jord86 like this.
  3. Adamfya

    Adamfya Active Member

    Cant you just drop the plasterboard onto the exposed beams....
     
    WillyEckerslike likes this.
  4. koolpc

    koolpc Screwfix Select

    Dont go cutting if unsure. Get an SE in to be safe.
     
  5. woodbutcherbower

    woodbutcherbower Well-Known Member

    What Severntrent said. I did a job last year for a customer who had done exactly what you describe. He'd then put new floorboards over the cut-down joists to create the country manor house effect he was after. To be fair to the guy - he'd done a super job and it looked great - but the joists were now only 4" x 3" and the floor above bounced like a trampoline. He was reluctant to undo all of his handiwork (100% understandable) so I had to prop up the floor with Ackrows and put in a central steel supported by padstones concealed in the stone walls of the property. I then clad it in reclaimed timber to make it look like a big beam.

    Joists are the size they are for good reasons ....

    IMG_2371.JPG
     
    CGN likes this.
  6. CGN

    CGN Screwfix Select

    nice job
     
  7. gb2021

    gb2021 New Member

    Thanks so much for all the advice - really appreciated. I totally take on board all the comments. I have one query. In the pic attached the red arrow shows the bracket which attaches the joist. The blue line shows the proposed cut. I was just wondering, if the bracket is attached this high up (ie doesn't span the width) , why would it affect the structural strength to cut off this section? Probably a stupid question! joist2.jpg
     
  8. gb2021

    gb2021 New Member

    p.s I'm trying to avoid overboarding because the ceiling is already low!
     
  9. woodbutcherbower

    woodbutcherbower Well-Known Member

    Cheers CGN !! One does one's best .....
     
    CGN likes this.
  10. woodbutcherbower

    woodbutcherbower Well-Known Member

    Stop it. There's no such thing if you don't know the answer, so stop putting yourself down. There are a lot of good people on here who will willingly share their expertise and give you sound advice. People like you at least have the sense to ask questions so you'll get it right - many don't. I'm sure you'll fix this one way or another.
     
    koolpc and CGN like this.
  11. Jord86

    Jord86 Screwfix Select


    Severntrents answer in post 2 was the reason, you're effectively turning an 8x2 into a 6x2 x the whole floor area, the batten/cleat nailed on the side of the joist provides no strength whatsoever it's just there to attach the plasterboard to. Board the undersides of the joists, it's only an extra 15mm or so.
     
    CGN likes this.
  12. CGN

    CGN Screwfix Select

    What age/style house is it?
     
  13. gb2021

    gb2021 New Member

    Thanks for the reply. It was built in the 1980's. Terraced. (hence I assumed that the bit of the beam which is left exposed may have been a faux beam)
     
  14. gb2021

    gb2021 New Member

    Yes I understand the battern provides no strength. The red lines indicate the depth of the bracket on the right. The "exposed" bit of the beam (blue arrow) is approx 50mm so boarding over the top would effectively lower an already very low ceiling (if I wanted it flat) by 65mm.
     
  15. Starslikedust

    Starslikedust Active Member

    Hi

    Summarising the points above

    Yes, but first get the advice of a structural engineer and it may require additional supports, e.g. a steel beam. The group is indicating this is a disruptive option but may get what you want.

    Either plasterboarding but with lower ceilings or (I suppose) living with it and painting the beams with the same colour also works but not quite what you were after.
     
  16. Severntrent

    Severntrent Screwfix Select

    Didn't notice those fixing brackets, unusual way of fixing timber, a bit disconcerting more suited to steel beams. Are all the beams so fixed?
     
  17. stevie22

    stevie22 Screwfix Select

    It would be worth a proper look if you really want to do this.

    Floor joists are sized to the biggest span so that all the wall plates are the same level and the floors are obviously level. It may be that there are areas where the span is small enough to work with a shallower joist and you could get away with what you want to do. BUT you need an SE to confirm this for you.
     
  18. gb2021

    gb2021 New Member

    Thanks for all the replies. I guess an SE is the way forward. I was just wondering why, if the joist is supported by a bracket which doesn't span its entire depth (as pic hopefully shows), removing the bottom section (in black) would affect its strength? i would have assumed that the bit below just adds weight to the bracket rather than any structural strength to the joist itself. Cheers again for your interest joist 3.jpg
     
  19. Adamfya

    Adamfya Active Member

    Could sister the joist add strength in this case?
     
  20. Severntrent

    Severntrent Screwfix Select

    But you are not just removing the bit below the bracket you are removing 50mm along the complete length of the joist??
     

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