How to Extend PVC Pipe on a Roof Vent

PVC pipe is a durable plastic pipe used in a variety of applications including water distribution, sewer lines and drains. PVC pipe is also used for venting, which extends up to the roof of the house. Generally, the vent should be one-foot high, but requirements vary by jurisdiction. You can quickly extend the PVC pipe on a roof vent. Before installing the extension, check your jurisdiction's building codes to ensure you can install the extension on the outside of the house.

Fine sandpaper
Tool caddy
Latex gloves
Schedule 40 PVC pipe (the length required to extend the vent)
PVC pipe coupling
PVC primer
PVC solvent cement
Clean rag

Instructions

- 1
  Turn off any equipment or appliances attached to the PVC pipe vent. PVC pipe roof vents are used to ventilate an HVAC unit or gas water heater. Turn off the heat or air conditioning and turn off the main valve for the water heater.
- 2
  Remove burrs and rough edges from the PVC pipe that you will attach to the roof vent, using fine sandpaper. Put on latex gloves.
- 3
  Apply PVC primer to the inside of half the coupling. Apply PVC primer approximately 2 inches in length to the outside of the PVC pipe. Immediately apply PVC solvent cement on top of the primer on the inside of half of the coupling. Apply PVC solvent cement on top of the primer about 2 inches on the outside of the PVC pipe. Insert the end of the PVC pipe with primer and solvent cement applied to the inside of the coupling on the end where the primer and solvent cement was applied. Turn the joint approximately one-quarter to weld the connection. Allow the weld to cure.
- 4
  Put the welded PVC coupling and pipe, latex gloves, PVC primer and PVC cement into a tool caddy to take to the roof of the house. Find a secure place on the roof near the PVC roof vent to place the tool caddy for easy access to the supplies needed to extend the vent.
- 5
  Remove the vent cap from the PVC pipe. Put on latex gloves. Wipe the PVC vent pipe with a clean, dry rag to remove any dirt and debris.
- 6
  Apply PVC primer to the inside of the other half the coupling that’s welded to the PVC pipe extension. Apply PVC primer about 2 inches outside of the PVC vent pipe. Immediately apply PVC solvent cement on top of the primer on the inside of half of the coupling. Apply PVC solvent cement on top of the primer about 2 inches on the outside of the PVC vent pipe. Insert the end of the PVC coupling with primer and solvent cement applied to the outside of the PVC vent pipe. Turn coupling approximately one-quarter to weld the connection.
- 7
  Allow the weld to cure completely. After the weld is dry, replace the vent cap.

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