Simple Guide: How to Install a Toilet Flange

Learning how to install a toilet flange matters because the flange anchors the toilet to the drain and seals the connection. A flange that sits too low, too high or unsecured lets the toilet rock and leak. The work needs care with the height, the seal and the bolts, and it is one of the more precise jobs in a bathroom.

What the flange does

The closet flange is a ring fitted over the drain opening in the floor. It holds the toilet's outlet over the drain and gives the bolts a solid place to anchor. The toilet sits on a gasket or wax ring that seals between the flange and the bowl. If the flange is cracked, loose or set at the wrong height, the seal will fail, and water can leak onto the subfloor.

Quick facts: how to install a toilet flange

Quick facts
Time needed	Two to four hours, depending on the floor and the access
Tools	Level, tape measure, drill, bolts, wrench, putty knife, wax ring or gasket
Key check	The flange top sits level with or slightly above the finished floor
Call a plumber if	The subfloor is rotted, the drain is cracked, or the flange cannot be fixed

Step 1: remove the old flange and check the drain

Remove the toilet and scrape off the old wax. Check the old flange for cracks, corrosion and movement. Look down the drain for debris, and make sure the drain pipe is in good shape before fitting a new flange. A soft or rotted subfloor must be repaired before the flange goes back in.

Step 2: set the flange at the right height

The top of the flange should sit level with the finished floor, or up to about a quarter inch above it. A flange that sits too low will not seal well, and one that is too high can stop the toilet from sitting flat. Use a spacer ring if the height is off, since a repair ring can correct the height without changing the drain.

Step 3: secure the flange to the drain

Fit the flange over the drain opening and attach it with screws or bolts to the subfloor. Tighten gently and check the level in all directions. A flange that rocks or sits on one side will leak once the toilet is set down.

Step 4: seal and set the toilet

Place a new wax ring or gasket on the flange, following the product instructions. Lower the toilet straight down onto the bolts, press it down firmly, and tighten the nuts evenly. Do not overtighten them, because a cracked porcelain bowl is expensive to replace.

Safety when working on a toilet flange

Shut off the water and flush the toilet before removing it. Wear gloves and eye protection when scraping old wax. Keep the drain covered while you work so tools and debris do not fall into the pipe. Lift the toilet with help, since the bowl is heavy and can crack if dropped.

When the subfloor is damaged

A flange that sinks, moves or sits on soft wood points to subfloor damage. Rot and water damage must be repaired before a new flange can hold. This repair is more involved than a flange swap, so a licensed contractor or plumber should check it.

When to call a professional

Call a plumber if the drain pipe is cracked, if the subfloor is soft, or if the flange cannot be set level. A plumber can also correct a flange that sits too low or too high using the right repair parts.

Keeping the seal sound

Check the base of the toilet every few months for water stains, a loose feel or a faint sewer smell. A careful check after any work on how to install a toilet flange catches leaks early. Tighten the bolts gently if the toilet moves, and replace the seal promptly if it leaks.

How to install a toilet flange: check the subfloor first

Before you fit a new flange, check the subfloor around the drain for softness or rot. A flange screwed into weak wood will move under the toilet, and the seal will fail. If the floor is sound, the next step is to set the flange at the right height, since that height decides how well the wax ring or gasket seals.

Learning how to install a toilet flange with the right height is the key to a leak-free connection. Measure the distance from the finished floor to the top of the flange, and aim for a flange that sits flush or slightly above the floor.

Working with the toilet removed makes how to install a toilet flange much easier, since you can see the drain opening and reach the screws. Secure the flange with screws that suit the pipe and the material. Do not overtighten them, because cracking a plastic flange is easy to do. Once it is fixed, test it by laying a straightedge across the finished floor. A flange that sits level and firmly anchored keeps the toilet steady for years, and when you know how to install a toilet flange correctly, the first flush will show whether the seal holds. If you plan to repeat how to install a toilet flange in another bathroom, keep notes on the height and the screw sizes.

Related reading

• How to Replace a Toilet: Remove, Reset the Wax Ring and Seal
• Toilet Leaking at Base: Causes and What to Do Next
• Practical Guide: How to Clean a Toilet Tank and Its Parts
• Practical Guide: How to Turn Off Water to Toilet Before a Repair

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