How to install copper pipe.

Discussion in 'Plumbers' Talk' started by davidnb, May 31, 2022.

  1. davidnb

    davidnb Member

    Hoping for some guidance.

    I am repiping my heating and wondering if I can safely notch these joists 20mm to allow pipes to sit without significantly weakening them. Floor joists are 4 inches. The joists sit on walls that are too close together to allow me to get pipes under the joists. My other options are go plastic or put short lengths of copper in and solder together as I go.

    What do the experts think. Many thanks.

    Attached Files:

  2. FlyByNight

    FlyByNight Screwfix Select

    How deep are the joists?

    you can notch 0.07 to 0.25 of teh length from each end - so you could be ok. Max depth is 0.125 joist depth.#
  3. davidnb

    davidnb Member

    Okay thanks for the reply. Do you mean 0.125 of the joists depth so 12% of the joists depth. Sorry I don't understand what the o.07 to 0.25 relates to could you explain that. Sorry I'm okaynwith my plumbing skills just not sure about these joists. Thank again
  4. FlyByNight

    FlyByNight Screwfix Select

    Yes 12.5% of depth So a 200mm joist can be notched by 25mm, a 150mm by 19mm.

    If a joist is 1m long you can notch betwen 70mm and 250mm from each end On a 3m joist between 210 and 750 from each end.

    Centre line holes are between 0.25 and 0.4 from each end. is a diagram which shows it. US rules are different and you need to make sure you look at UK based diagrams - which my link is
  5. Hans_25

    Hans_25 Screwfix Select

    I wouldn't be notching 4" joists, that's very shallow. Why are they only 4" deep, standard joists are 8" or 9" deep.

    You might be able to notch them if you add strength across and under the notch using a steel plate or similar.
  6. davidnb

    davidnb Member

    Yes mine are only 100mm or 4 inch. Shallow joists so don't think I am going to notch them.
  7. davidnb

    davidnb Member

    Yes Hans... very shallow at 4 inch. It's a 1970s house. Guess they used 4 inch joists as they were cheaper option. There are regular brick walls between the joists which makes getting pipes down even harder. I do have some steel I could use to reinforce but that's even more work. I think despite my desire to use copper throughout I am going to have to use plastic for this part of the project.
  8. davidnb

    davidnb Member

    Thank you that is very helpful.
  9. FlyByNight

    FlyByNight Screwfix Select

    In the second page of the link, you could just go to 15mm at certain points but that is all. In te right location, 25mm holes are possible, so drilling 18mm for 15mm plastic is a possibility. Always follow teh guides and if unsure, professional advice.
  10. Dean Worsell

    Dean Worsell Member

    It looks like the floor is suspended so run the pipes underneath and clip to the under side of the joist you may have to have a few extra joints or use plastic pipe
  11. Mr right first time

    Mr right first time Active Member

    Just use plastic, I’d rather replace the pipe in 25 years and make sure my ceiling didn’t fall down because I notched some joists.
    davidnb likes this.
  12. Ind spark

    Ind spark Screwfix Select

    Could you not take some more floor up push the pipe under and turn it, then clip underneath.
  13. davidnb

    davidnb Member

    No as brick walls are very close to support the joists.
  14. davidnb

    davidnb Member

    Yes I think that's what I will do. Just get the longest lengths of copper I can and then join. Plenty of space to solder good connections.
    Dean Worsell likes this.
  15. davidnb

    davidnb Member

    Yes quite open to the idea of some plastic but I have copper in garage.
    Dean Worsell likes this.
  16. Dean Worsell

    Dean Worsell Member

    As they always are when you have a suspended floor with dwaft walls, pipes need to go under the joist as you only have 4x2 timbers
  17. davidnb

    davidnb Member

    Yes I thought so. Didn't know the correct term was dwarf walls. I will it them under the joists and join up as I go. May use some plastic also to speed the job along. Thanks for your reply.
    Dean Worsell likes this.
  18. luna19

    luna19 New Member

    Use plastic. Also very few(or no) joints in pipe work run

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