How to Rough In a Toilet Flange
Toilet flange installation has gotten complicated with all the pipe materials, measurement specifications, and sealing options flying around. As someone who has roughed in plumbing for bathrooms of every layout, I learned everything there is to know about getting the flange right. Today, I will share it all with you.
Tools and Materials
Probably should have led with this section, honestly—gather these first:
- Toilet flange
- PVC pipe and fittings
- PVC glue and primer
- Wax ring
- Measuring tape and level
- Drill and screws
Measuring and Positioning
That’s what makes proper measurement endearing to us plumbers—it prevents leaks and rework:
- Standard distance from finished wall to flange center is 12 inches
- Measure from the back wall, not baseboards
- Mark the spot clearly on the floor
- Flange should sit flush with finished floor—not above or recessed
Cutting and Attaching Drain Pipe
- Cut PVC pipe to allow flange to sit flush with floor
- Deburr cut edges for smooth end
- Apply primer to inside of pipe and outside of fitting
- Apply PVC glue to both areas
- Push pipe into fitting and twist for strong bond
- Check alignment with level before glue dries
Setting the Flange
- Place flange over drain pipe—should fit snugly
- Tap gently with rubber mallet if needed
- Align bolt holes with marks on floor
- Drill pilot holes through marks
- Fasten flange to floor with screws—ensure no wobble
Installing the Wax Ring
Place wax ring directly on flange, fitting snugly around the opening. If your ring has a plastic funnel or horn, fit it inside the flange for extra leak protection.
Final Checks
- Double-check alignment—flange should be level and centered
- Use level to confirm everything is straight
- Wipe away excess glue
- Clean area of debris
- Verify all connections are tight and secure
Common Mistakes
- Improper measurement: Always measure from finished wall
- Loose flange: Use correct screws for your floor type
- Wrong height: Flange must be flush with finished floor
Maintenance
Inspect periodically for wear or damage. Check for leaks or unusual smells around toilet base. A wobbly toilet can damage the flange—tighten bolts but avoid overtightening.
