Re-plumbing house, runl Pex through joist or under the joists?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by pitterpat, May 12, 2013.

  1. pitterpat

    pitterpat HandyWOMAN

    Messages:
    46
    Location:
    Indianapolis
    I bought a house 1 1/2 yrs ago that was built in 1956 so you know it has galvanized pipe for the water supply. I want to replace all of the plumbing pipes and am planning on using Pex and a manifold. Currently, the basement where the water supply enters the basement has an open ceiling and the water pipes hang under the joists. Is there any reason that I could not run the Pex through the joists when going across the joists and run them up in the joists when running them parallel to the joists? Yes, I will rent a right angle saw to drill the holes in the joists and I know there is a formula for where I should drill the joists; also I think the joists are 2 x 8's' the house has 1 full bath, 1/2 bath and kitchen and lines for washer in the basement and 2 outside spigots. I would like to add and laundry sink in the basement.

    Thanks! Pat
  2. cwhyu2

    cwhyu2 Consultant

    Messages:
    1,348
    Location:
    Cincinnati OH
    Through the joists is okay.
  3. Terry

    Terry Administrator Staff Member

    Messages:
    15,416
    Location:
    Bothell, Washington
    You leave 2" on the top and 2" on the bottom of the floor joist, drilling in the middle portion.
  4. pitterpat

    pitterpat HandyWOMAN

    Messages:
    46
    Location:
    Indianapolis
    Thanks!

    Another question:
    As I stated I want to put the pipes up through and between the joists; the main pipe from the well tank goes under the joists because when the house was built the fashioned a cold air return using 2 joists and putting sheet metal on the bottom to box it in. Don't know if that was the process back then but that is what they did here. I would like to run the pex through this "made up" cold air return to get that pex up....was thinking about it all day and what I came up with was to drill a hole on both sides and put a length of PVC that will span both sides of this cold air return, then run the pex through the PVC. To seal around the PVC I would caulk it or put the aluminum tape around it to the joist.

    I know this isn't a standard practice today but I don't think I can hurt the cold air return....when they put the sheet metal on the bottom all they did was nail it up there w/o putting any kind of tape on the seam; so what I do can't make it anymore leaky (air).

    Concerns, questions.
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