Toilet Flange Installation: A Comprehensive Guide



A toilet flange is a crucial component of your toilet installation, ensuring a secure and leak-proof connection between the toilet and the drainpipe. Whether you're installing a new toilet or replacing an old one, understanding the process of installing a toilet flange is essential. This comprehensive guide will walk you through the steps involved in installing a toilet flange on various types of floors, including concrete, below floor level, and with extensions.

Installing Toilet Flange to Concrete Floor:

  1. Gather Materials: Before you begin, ensure you have the necessary tools and materials, including a toilet flange, wax ring, closet bolts, wood screws or cement screws, wrench, and screwdriver.

  2. Mark the Flange Location: Locate the existing drainpipe and mark the center point on the floor where the flange will be installed.

  3. Remove Old Flange (if applicable): If replacing an existing flange, carefully remove it using a pry bar or hammer.

  4. Position the New Flange: Place the new flange over the marked location, ensuring the outlet hole aligns with the drainpipe.

  5. Secure the Flange: Use wood screws or cement screws to secure the flange firmly to the subfloor. Ensure the flange is level and flush with the finished floor.

  6. Install Closet Bolts: Insert the closet bolts through the slots in the flange, ensuring the threads extend above the flange.

  7. Attach Wax Ring: Apply a layer of petroleum jelly around the outlet hole of the flange. Place the wax ring over the flange, ensuring the horn fits snugly inside the outlet hole.

Installing Toilet Flange Below Floor Level:

  1. Raise the Floor Level: If the floor level is below the drainpipe, you'll need to raise it to accommodate the flange. This may involve adding a layer of plywood or using a flange extension kit.

  2. Follow Concrete Floor Installation Steps: Once the floor level is raised, follow the same steps as for installing a toilet flange on a concrete floor.

Installing Toilet Flange Extension:

  1. Choose the Right Extension: Select a flange extension kit that matches the height difference between the floor level and the drainpipe.

  2. Install the Extension Base: Attach the extension base to the drainpipe using the provided hardware. Ensure the base is level and secure.

  3. Install the Flange: Mount the toilet flange onto the extension base, following the same steps as for installing a flange on a concrete floor.

Replace Flange Under Toilet:

  1. Disconnect Water Supply: Turn off the water supply to the toilet and flush the tank to drain remaining water.

  2. Remove Toilet: Disconnect the toilet from the drainpipe and carefully lift it away from the floor.

  3. Remove Old Flange: Use a pry bar or hammer to carefully remove the old flange from the subfloor.

  4. Install New Flange: Follow the appropriate installation steps for the type of floor you have (concrete, below floor level, or with extension).

  5. Reinstall Toilet: Carefully lower the toilet onto the new flange, aligning the bolt holes. Secure the toilet with the closet bolts and washers.

  6. Reconnect Water Supply: Reconnect the water supply line to the toilet and turn on the water supply. Check for leaks.

Installing Toilet Flange Measurements:

  1. Flange Outlet Hole: The standard diameter of a toilet flange outlet hole is 4 inches.

  2. Flange Bolt Holes: The center-to-center distance between the flange bolt holes is 6 inches.

  3. Flange Height: The standard height of a toilet flange from the finished floor is 12 inches.

Additional Tips:

  • Always wear safety glasses and gloves when working with tools.

  • Use a level to ensure the flange is perfectly level.

  • Apply a sealant around the base of the flange to prevent leaks.

  • If you're not comfortable with DIY projects, it's always best to hire a professional plumber.


Installing a toilet flange may seem like a daunting task, but with the right tools, materials, and knowledge, it can be done successfully. By following the steps outlined in this guide, you can ensure a secure and leak-proof connection between your toilet and the drainpipe, preventing potential plumbing problems down the road. Remember, safety is always a priority, so don't hesitate to seek professional assistance if you're unsure about any aspect of the installation process.

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