How to Install a One-Piece Toilet
Part of our Toilets & Bidets guides.
One-piece toilets are heavy; lift with a helper. Turn off the water (and power at the breaker for anything electrical) before starting, and follow the product manual where it differs from these general steps.
| Time | 1-2 hours |
|---|---|
| Difficulty | Moderate |
| Tools | Adjustable wrench, putty knife, level, new wax ring, hacksaw |
Step by step
- Drain and remove old toilet. Shut off water, flush, sponge out remaining water, unbolt and lift off.
- Clean flange. Scrape the old wax; inspect the flange for damage.
- Check rough-in. Confirm 10 or 12 in matches the new toilet.
- Set bolts and wax ring. Install new flange bolts and the wax ring.
- Set toilet. Lower straight onto the bolts; press down evenly.
- Tighten. Tighten nuts alternately; don't overtighten.
- Connect supply and test. Connect, open the valve, flush several times and check for leaks.
Tips & common mistakes
- Rock test: the toilet shouldn't move; use shims if the floor is uneven.
- Cut excess bolt length before caps.
Check the flange
The flange should sit on top of the finished floor or no more than a quarter inch below. If the new floor raised the height and the flange is now too low, use a flange extender or an extra-thick wax ring. Broken flange slots can be fixed with a repair ring rather than replacing the whole flange.
Wax ring vs wax-free seal
Traditional wax rings are cheap and reliable when the toilet is set once and pressed straight down. Wax-free foam or rubber seals tolerate repositioning better if you're working alone. VEVOR's one-piece toilets include a wax ring.
Uneven floors
If the toilet rocks, slide plastic toilet shims under the base before tightening. Rocking breaks the wax seal over time and causes leaks. Trim shims flush and caulk around the base (leave a small gap at the back so leaks can be seen).
After installation
- Check the fill valve height and water level per the manual.
- Test both buttons on dual-flush models.
- Look for drips at the supply line and around the base after several flushes, and again the next day.
Frequently asked questions
Should I caulk around a toilet?
Many codes require it; leaving a small gap at the back lets leaks show.
How heavy is a one-piece toilet?
Often 90-100 lb or more; lift with a helper.
Do I need to replace the shut-off valve?
Replace it if it's old, leaking or won't close fully.
Can I install a toilet on tile?
Yes; the flange should sit level with or slightly above the finished floor.
How do I fix a rocking toilet?
Use plastic shims under the base before tightening bolts.