How to Install Plumbing in a Wall

Plumbing supply and drain lines inevitably have to be installed inside walls to be available at their points of use.

Drill holes in the studs to pass pipes through.Drill holes in the studs to pass pipes through.
The installation is best accomplished during the framing phase of construction, although piping is frequently added later. The most important thing to remember is to place pipes at least an inch from the edges of studs or rafters to avoid screwing into them with drywall screws. Protect them with metal plates attached to the studs when this is not possible.

Plan the path of water supply lines from the source to the point of use and the route of drain lines from the the point of use to the sewer. Remember that drain lines must be installed with a downward slope.

Drill holes in the studs or rafters along the horizontal path of water lines with a spade bit slightly larger than the diameter of the pipe. Drill the holes one-by-one, passing a length of pipe through each to align the position of the hole in the next stud. Remember to drill each hole in the middle of each wooden member, at least an inch from each edge to avoid contacting the pipe with drywall screws.

Make notches in framing with a reciprocating saw for waste pipes to avoid weakening wooden members. Remember to keep an overall downward slope. Set the pipe inside the notches and attach metal pipe-guard plates over the openings.

Make holes for vent and vertical waste lines through top and bottom plates with a hole saw. Use a saw that has a slightly larger diameter than the pipe. In some cases, you may have to make pilot holes with a spade bit and cut the holes out with a reciprocating saw.

Install blocking in the wall and anchor tub and shower diverters to it with pipe strapping. Use strapping to secure all stub-outs for supply and drain lines to a stud. If no stud is available, install blocking and secure the pipe to that.

Things You Will Need

  • Drill
  • Spade bits and hole saws
  • Reciprocating saw
  • Metal pipe-guard plates
  • Pipe strap
  • Screws
  • No. 2 Phillips drill bit

Tips

  • Three-inch vertical waste lines typically pass in the space between studs and do not need to be protected since there is no danger of contacting them with drywall screws.
  • Whenever you attach a length of copper pipe to a framing member, it is a good idea to install a rubber membrane between the pipe and the wood. This will help reduce sound from vibrations as the water runs through the pipe.

Warning

  • Copper pipes expand and contract with fluctuating temperatures, so make sure the holes you drill are large enough to allow for this movement. A good rule of thumb is that the hole should be large enough for the pipe to slide through easily without sticking.

About the Author

Chris Deziel has a bachelor's degree in physics and a master's degree in humanities. Besides having an abiding interest in popular science, Deziel has been active in the building and home design trades since 1975. As a landscape builder, he helped establish two gardening companies.