How to Add New Plumbing Upstairs for a Bathroom


Add value and convenience to any home by installing a new bathroom on an upper floor. Setting the plumbing for a new bathroom requires you to connect supply water pipes and drainpipes to existing systems. Once the new plumbing is in place, you can add fixtures and furniture to complete the room.

Things You'll Need

  • Reciprocating saw with drywall blade
  • Hacksaw or pipe-cutting tool
  • ABS cement
  • ABS Y-fitting
  • Marker
  • Cloth
  • Push-to-fit T-fittings, 2
  • Water supply pipe (CPVC, Copper or PEX)
  • Pipe strap
  • Hammer

Connecting to Drain Lines

  • Contact your local building department to see whether a permit is needed for adding new plumbing.

  • Remove the drywall in the bathroom against a wall that has the nearest access to the plumbing lines, if there is no direct access to plumbing within an access panel in the room. The drywall can be removed using a reciprocating saw and a drywall blade. Pull out the drywall in small sections and discard.

  • Locate a drain line within the wall.

  • Turn the main water line ball valve 90 degrees clockwise to shut off the flow of water to the entire plumbing system. Open all the faucet taps inside the house to drain as much water as possible from the lines.

  • Cut out a 5-inch section of the waste line using a hacksaw or pipe-cutting tool.

  • Apply a layer of ABS cement to the inside of an ABS Y-coupler.

  • Press the coupler into the hole that you cut into the drain line until the fitting slips over both ends of the pipe. Make sure the opening on the Y-fitting is pointed toward the inside of the bathroom to allow for easy access later on. Allow the cement to set for 10 minutes. Once dry, the Y-fitting will provide a spot to connect the sink and toilet drains.

Connecting Supply Lines

  • Locate existing hot and cold water lines inside the basement, crawlspace or access panel closest to the bathroom.

  • Turn the ball valve on the main water line 90 degrees clockwise to turn off the water to the house while you work.

  • Mark a 5-inch section on both the hot and cold water lines.

  • Cut on the marks with a pipe-cutting tool or hacksaw.

  • Clean the edges of the cut pipes with a cloth to remove any plastic or copper shavings.

  • Place push-to-fit T-fittings into one side of each of the supply lines, with the third opening facing the direction of the bathroom. The fitting will audibly snap into place.

  • Gently pull back on the fittings and the other side of the cut pipe to slip the pipes into the other side of the fittings. Release the fitting and the pipe to complete the connection.

  • Thread the new water pipes into the wall in the direction of the bathroom and insert the base of the pipes into the openings on the T-fittings. This will connect the water lines to the existing plumbing system.

  • Have a helper guide the tops of the pipes into the opening in the upstairs bathroom wall. Temporarily secure the tops of the pipes against a stud in the wall by placing a pipe strap around each line and tapping the provided nails into the studs. This will hold the lines in place until you are ready to add furniture and individual fixtures.

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