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joist

A joist is a horizontal structural member used in framing to span an open space, often between beams that subsequently transfer loads to vertical members. When incorporated into a floor framing system, joists serve to provide stiffness to the subfloor sheathing, allowing it to function as a horizontal diaphragm. Joists are often doubled or tripled, placed side by side, where conditions warrant, such as where wall partitions require support.
Joists are either made of wood, engineered wood, or steel, each of which have unique characteristics. Typically, wood joists have the cross section of a plank with the longer faces positioned vertically. However, engineered wood joists may have a cross section resembling the Roman capital letter "I"; these joists are referred to as I-joists. Steel joists can take on various shapes, resembling the Roman capital letters "C", "I", "L" and "S".
Wood joists were also used in old-style timber framing. The invention of the circular saw for use in modern sawmills has made it possible to fabricate wood joists as dimensional lumber.

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  1. J

    Is this acceptable?

    Just had plumber come round to take heating pipes down from upstairs down to new radiator in the living room. Couple of things: 1. He said the conduit would look neat just like on the original work done in the house - I don't think it does. 2. He's taken quite a large chunk out of one of the...
  2. F

    Cutting tracks for pipework

    Hi guys, first post here. Joined up to do a bit if research into a CH system we're having installed in the coming months. Our flat has a concrete cap on the solemn, and no gap between joists and floor/concrete, so only way to go below floor is to cut channels/tracks into the caber floor/joists...
  3. M

    New build in copper

    Hi has anyone got much experience of doing new builds in copper? Got some to do there traditional joist not the engineered ones.
  4. T

    Shower waste pipe

    customer wants a flush level shower but the joists run the wrong way to route the waste. Any other ideas other than building a plinth that she is not keen on. She is saying just notch the joists errrrr NO
    • tommy1712
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    • Replies: 8
    • Forum: Plumbing Jobs | The Job-board
  5. Z

    Spacing query for underfloor heating between joist, 1st floor.

    Hi guys, Looking for info on pipe spacing for upstairs wet underfloor heating between joists. The joists are 8 inches wide and the ceilings 10ft high, Rooms 15 sqft . Should I have just one pipe running in between each joist or should I have the circuit running up and down in between each...
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    • Replies: 12
    • Forum: Plumbing Jobs | The Job-board
  6. T

    Bit of a nightmare

    Customer wants a low profile walk in shower tray started to first fix the pipes and waste, problem is my waste, pulled floorboards up I have about 3 inch gap to position waste and run the pipe out the wall, I was thinking run wwaste thru the wall and connect to a flexi waste, but there is a...
  7. M

    Discharging toilet in to horizontal tee branch

    Hey is it ok to discharge a toilet in to a horizontal tee branch instead of an elbow as shown in the picture. The soil pipe is running between the joist and carries on in 1.5inch to pick up the bath.
  8. T

    advice wanted with plastic pipe fitting

    hi all just want a bit of advice please, im running a new jg plastic pipe lines hot and cold due to refitting bathroom, i want it to go through the joist as this is the most direct route to the mains but they will pass over a halogen light fitting that is recessed in the ceiling below, will it...
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    • Forum: Plumbing Jobs | The Job-board
  9. A

    Advice on a newly installed system

    I am looking for some advice from engineers regarding a central heating system we have just had installed which is causing us a few problems. Every time the system is on there is a fair bit of noise from what I think is a problem with the pipe work, the noise sounds like 2 pipes knocking...
  10. S

    Triple joist

    Hi all I need to drill 2 x20mm hols through a triple joist. What is the best tool ? I was thinking of an auger bit on my sds but not sure Thanks
  11. J

    40mm Waste across Joists.

    This is a big no no, I know that but, are ther any methods for replacing the strength that has been removed by using plates or "Fish Plates" drilled and bolted through the joist.
  12. J

    loft space cylinder and joist loading

    Hi all, looking to fit an unvented cylinder in a bungalow loftspace.  Anybody know if there's a calculator online or has calculation formula for working out if the roof joists are up to handling the proposed 180 litre cylinder.  Last thing I want is the cylinder dropping through on...
  13. D

    tool for cutting a floorboard

    which tool would/do you use to cut 1/ several floorboard/s to gain access ? sabre saw? multitool ? circ 240v/batt ?
  14. S

    Cutting hole for toilet waste between joists

    Hi all, Newbie question, sorry if been asked before but I've searched and come up with nothing! I'm looking at buying a house but it has a seriously small bathroom (4'9" wide and 9'10" long with a chimney breast along one wall), so there is no bath in, just a shower. I think I could install a...
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    • Forum: Plumbing Jobs | The Job-board
  15. P

    waste soil pipe 150 centre from wall

    hi, just fitting a bathroom suite and as usual the waste pipe for the wc is going through the floor, i told the customer i would move this further back so i could fit a normal new c/c wc altho on inspection today there is no way i can move this pipe back as there is a supporting joist in the way...
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  16. W

    I have still never lifted a floorboard...however...

    I'm about to. To move a radiator. So to run through proceedure. Am I right if I say: Remove carpet from area, place somewhere protected. Identify joists from pattern of where nails go through floorboards. Cut through floorboard you want to lift along where you imagine the joist runs and in...
  17. N

    Maybe a tad too much !

    Found this a few under a customers floor a few months back, it was loft conversion done VERY badly. There was shower cubicle fitted tight under the sloping ceiling with the tray up on blocks, when my mate stood in it and shut the door it jammed his head against the ceiling, absolutely pi**ed...
  18. M

    Shower waste hits joist

    Hello, Just bought a shower tray only to find the waste is slap bang over a joist. I really don't want to build a step up. Can I .. hear me out first .. cut the joist and use trimmers. Lots of them? Thanks
  19. M

    a mare of an installation

    im currently working on a house - a lot of plumbing, kitchen and bathroom. now the bathroom ive lifted the floor boards today to have a look at the wastes and the 1" and a quarter and inch and a half from the basin and shower respectively are notched into joists trhough every single one... so...
  20. L

    Notching and drilling joists

    Does anyone find notching joists a complete pain and are there any products out there that are an alternative or any other ways of hiding pipework?
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