How to Plumb Your House With PEX

PEX pipe with metal insert fittings and stainless steel clamp bands is one alternative to copper and CPVC for interior hot and cold plumbing installed in trunk and branch fashion. According to the Plastics Pipe Institute in Irving, Texas, PEX offers resistance to scaling and corrosion, resists freeze damage, is easy to install and makes water systems more efficient. (See Reference 1.) PEX is approved for use in current model plumbing codes; however, some jurisdictions using older codes may not allow its use.

Things You'll Need

• PEX pipe in 1", 3/4" and ½" sizes
• Stainless steel clamp bands in 1", 3/4" and ½" sizes
• Stainless steel clamp band ratchet tool
• 2 3/4" slip/thread adapters
• 1"X3/4" reducing elbow
• Metal insert reducing tees in 1"X3/4"X1" and 3/4"X1/2"X3/4" sizes
• Metal insert elbows and reducing elbows in 1"X3/4", 3/4"X3/4", ½"X1/2" and 3/4"X1/2" sizes
• 1", 3/4" and ½" plastic pipe hangers and mounting clamps
• ½" slip/thread adapters
• Escutcheons (cover plates where fixture valves attach)
• ½"X3/8" angle stops (fixture valves)
• Pipe joint compound
• Protective plates and protective grommets

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Instructions

Install PEX Plumbing in House

1. Install a 1" diameter PEX water pipe supply line from the water source to the location of the hot water heater. For most homes a 1" diameter pipe will be sufficient but follow manufacturer's recommendations related to the amount of slack to leave in the pipe to allow for expansion and contraction.

2. Install one hot and one cold PEX water pipe trunk line of 3/4" diameter near each fixture or groups of fixtures. Snake these continuously throughout the home's framing, through holes drilled in the framing, being careful not to kink it. Adjust the size of these lines accordingly if the main supply PEX pipe size was increased beyond 1".

3. Cut 1" diameter PEX main water pipe near the hot water heater and insert a 1"X3/4"X1" Tee and use ratcheting tool to clamp the Tee in the 1" line. Attach 3/4" PEX water pipe to the 3/4" side of the Tee, clamp it and then connect other end to the water heater inlet using a 3/4" slip/thread adapter.

4. Slip the 1"X/4" reducing elbow into the end of the 1" supply line and attach using a 1" clamp and the ratchet tool. Slip the end of the 3/4" cold water trunk line onto the 3/4" side of the reducing elbow and attach using a 3/4" clamp and the ratchet tool.

5. Attach the 3/4" slip/thread adapter to the end of the hot trunk line near the water heater, clamp it onto the trunk line and thread it into the hot water heater outlet.

6. Cut hot and cold trunk lines at each fixture, insert reducing tees (3/4"X/2"X/4") and use the ratcheting tool to clamp each Tee into the 3/4" line.

7. Attach ½" hot and cold PEX water pipes to ½" side of reducing Tees, then clamp them using the ratchet tool and clamp.

8. Fasten the other end of the ½" lines to adequate blocking at the fixture location and cap lines until wall covering is installed and finished.

9. Support all pipes at regular intervals using appropriate clamps and hangers designed for use with PEX pipe.

10. Install escutcheons over pipes at each fixture and use the ratchet tool and clamp to secure ½" slip/thread adapter to each once the wall covering is in place and finished.

11. Thread angle stops onto the ½" slip/thread adapters.

Tips & Warnings

• Plan thoroughly before beginning this work. Follow applicable plumbing codes and use manufacturer's references to determine pipe sizes, types of fittings and fastening requirements. Don't mix different pipe materials without using approved transitional devices and fittings. Use an approved thread compound on metal fixture threads. When running lines through studs, keep them as close to the center of the studs as possible. Use protective plates on the edges of wooden studs adjacent to where the lines pass through them. Use protective grommets where lines run through metal studs.

• Installing plumbing in a house requires attention to detail and skill to make the system adequately functional, leak-free and durable. Persons with limited mobility and strength may find plumbing to be difficult. Persons with low mechanical aptitude may be exceptionally challenged when trying to install PEX plumbing in a house. Always follow local building codes and pipe, fitting and fixture manufacturers' installation instructions.

References

• Design Guide: Residential PEX Water Supply Plumbing Systems
• Plastic Pipe and Fittings Association

Resources

• Read this Article in Spanish
• Design Guide: Residential PEX Water Supply Plumbing Systems