A step-by-step guide to a secure, leak-free toilet flange installation
A toilet flange, also called a closet flange, is a pipe fitting that secures a toilet to the finished floor. The flange also securely attaches the toilet to your home's drainage system.
Properly installing a toilet flange is essential for preventing leaks, ensuring stability, and extending the life of your toilet. Whether you're tackling a new installation or replacing an existing flange during a remodel, this guide walks you through every step—selecting the right materials, positioning the flange correctly, and securing it to the floor.
This guide focuses specifically on installation. If your existing flange is damaged and needs repair, visit our How to Repair a Toilet Flange guide. For help selecting the correct flange, explore our Guide to Toilet Flange Types.
What You'll Need For This Project
- Toilet flange (PVC, ABS, offset, or cast iron)
- Oatey® Purple Primer
- Solvent Cement (for PVC/ABS installs)
- Wax ring or non-wax seal (e.g., Oatey® Standard Wax Bowl Ring)
- Toilet Bolts (e.g., Hercules® Johni-Bolts®)
- Drill or screwdriver
- Tape measure
- Saw
- Stainless steel or appropriate floor screws
- Safety gloves and eye protection
- Optional: Flange spacer or extender, hammer drill (for concrete)
Pro tip: Always match the flange material to the pipe (e.g., PVC to PVC). If you must mix materials, use a certified transition cement such as Oatey® ABS to PVC Transition Medium Bodied Green Cement.
Step 1. Select the correct flange type.
Match the flange material (PVC, ABS, cast iron) to your drain pipe. Depending on your drain configuration, you can opt for over-pipe or inside-pipe styles.
In high-moisture environments, like basements or areas prone to leaks, consider using stainless steel ring models.
If dealing with misaligned rough-ins, an offset flange can facilitate an outlet shift of up to two inches in any direction.
Step 2. Prep the drain pipe and subfloor.
Ensure the drain pipe is clean, dry, and the correct size, typically 3 inches or 4 inches. Measure and cut the pipe to the desired height.
Note: Chamfer and debur the pipe for a strong connection.
Inspect the subfloor to confirm it is level, dry, and debris-free. If installed on concrete, pre-drill anchor holes using a masonry bit and hammer drill.
Step 3. Dry fit the flange onto the pipe to check alignment.
Temporarily place the flange onto the pipe to ensure a proper fit and check for interference. Make sure that the bolt slots are positioned at the nine and three o'clock positions.
Mark the alignment between the flange and the pipe with a permanent marker, preserving the orientation for the final installation.
Step 4. Solvent weld.
First, apply Oatey® Purple Primer to the flange and drainpipe using approved application methods. Then, apply Oatey® Heavy Duty Clear PVC Cement to the flange and drainpipe using approved application methods.
Step 5. Install the flange onto the pipe.
Push the flange down onto the drainpipe until it sits on the finished floor.
Step 6. Anchor the flange to the subfloor.
Securely fasten the flange using stainless steel or corrosion-resistant screws. Always anchor it through to the subfloor rather than just the tile.
Proper anchoring prevents movement and maintains the seal. Avoiding "floating" flanges that aren't anchored is crucial, as they can shift under the toilet's weight and compromise the wax ring.
Step 7. Install closet bolts.
Insert closet bolts like Johni-Bolts® into the flange slots and secure them with washers and nuts. If you have thick floors or are using flange spacers, opt for longer bolts. For quicker installations, consider using quick-install washers to hold the bolts in place while positioning the toilet.
Step 8. Prepare for toilet installation.
When installing a toilet, place a new wax or non-wax ring on the flange. Never reuse an old ring, even if it looks intact.
Ensure the flange is at the correct height, ideally sitting on top of the finished floor. If the flange is flush, opt for a thicker wax ring to compensate.
For detailed toilet setting instructions, refer to our guide on How to Replace a Toilet Wax Ring.
Common Mistakes to Avoid
- Installing the flange below the finished floor: This can lead to poor wax ring compression and leaks.
- Using the wrong flange material: Avoid mismatched pipe and flange types unless you use approved transition materials.
- Loose installation: A flange not anchored securely can move or break over time.
- Reusing old bolts or wax rings: Always use new components for a reliable seal and easier installation.
For more guidance, read Five Best Practices When Installing a Toilet Flange.
Flange Installation Variations
- Installing on concrete: When working with concrete, it's essential to use concrete-specific anchors and a hammer drill. Before securing the flange, pre-drill the holes and clear any debris. Be ready for more preparation time than you would typically spend on wood subfloors.
- Damaged flange: If the original flange is damaged or sitting too low, consider using a Twist-N-Set® or Set-Rite® Flange Extension Kit. These options allow for retrofitting without the need to cut into floors or ceilings, making the repair process simpler and less invasive.
- Misalignment: Offset flanges provide a solution for minor adjustments when drain pipes are misaligned. It's important to mark the placement carefully before cementing, as the flange cannot be repositioned once set. Maintaining the proper slope in the waste pipe is crucial for ensuring effective drainage performance. For more information, read Should I Use an Offset Toilet Flange?
Correctly installing a toilet flange is essential for a durable, leak-free toilet installation. Whether you're a seasoned pro or tackling your first bathroom project, Oatey provides the products, expertise, and support you need to do the job right.
Frequently Asked Questions
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How do I know if my toilet flange is the right height?
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Your toilet flange should sit on top of the finished floor. If it's flush or slightly recessed, a flange spacer or thicker wax ring can help ensure a proper seal.
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Can I screw a toilet flange directly to the tile?
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Yes, as long as the screws go through to the subfloor (wood or concrete). Tile alone won't provide a strong enough hold.
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What happens if the toilet flange isn't level?
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An uneven toilet flange can prevent the toilet from sitting flat, leading to rocking, stress fractures, or a broken wax seal.
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Do I need to glue the flange into the pipe?
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Yes. Use the appropriate primer and cement for PVC or ABS installations. This creates a permanent, watertight seal.
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