How To - Lay Out Pex

Hugh the tech Ducky

How do you lay out pex pipes?

(video coming soon)

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A pex pipe layout is exactly as it sounds. You take a floor diagram of your house and plan approximate 300’ loops of pex pipe to warm your floors- starting at and ending where your Hydronics unit will be (utility room is a common place, although a closet may work). 

You can use graph paper, a loopcad software, or spray paint on your pink insulation. 

You can make copies of your floorplan and draw in the loops.

Example of a Pex Pipe Layout in CAD software

Pex Pipe Layout CAD software
When you do this you can keep in mind thermostat zones. Each loop of pex piping can connect to only 1 zone. So if you want your living room and bedroom on different zone, then the pex loops used for the living room will be different than the pex loops used in the bedroom.

General Rules for Loop Layout

  1. Loops begins and end at hydronics unit
  2. For rough estimates plan 1 foot of tubing for every square foot of flooring
  3. Loops should stay about 8-12” away from the next loop for ½” pipes, a little less (6-8”) for smaller pipes and slightly more (12-18”) for larger pipes.
  4. Suggested loop length is 300’, but no longer 350’. Shorter loops are fine
  5. The hottest water (hose coming out of the hydronics unit) should go to the coldest areas first (often near outside walls)
  6. Cold spots can also have pipes closer together.
  7. It is recommended to stay 12” away from the base of the toilet, because the hot water can melt their wax seal.
  8. Under a floor you often run a loop (down and back) between every joist.

Samples of PEX Layouts, the circular and the ZigZag

Pex Pipe Layout circular design

Pex Pipe Layout example zigzag pattern

Installing in a Concrete Floor

  • Insulation below concrete
  • Tubes stapled to insulation about 2 to 3’
  • Use Heat Sheet Insulation and walk your pex pipes into place
  • If using rebar- you may wire or zip tie to the rebar every 2 to 3’
  • Holey Hose Holder makes the
    install clean and easy

Gypcrete over wooden floor is very similar

  • Moisture mitigation and time to dry
  • Extra bottom plate for 1.5” thickness

These people are unrolling and stapling the pex pipes to the foam board.

Rolling Out the pex pipes

This is a finished photo of pex pipes running to a HUG Holey Hose Holder with cement starting to be poured in the background.

Pex pipes stapled to foam board