A wobbly toilet or a leak at its base often points to a single culprit: a broken toilet flange. This critical component connects your toilet to the drainpipe and secures it firmly to the floor. Replacing one, especially when it’s set in concrete, might seem like a job reserved for professionals.
However, with the right guidance and a bit of patience, it’s a manageable DIY project. This guide on how to replace a toilet flange on concrete will walk you through the entire process, from gathering your tools to setting the new flange, helping you restore your bathroom’s integrity and prevent potential water damage.
Tools and Materials You’ll Need
- New Toilet Flange (PVC or Cast Iron)
- New Wax Ring With Bolts
- Adjustable Wrench
- Putty Knife or Scraper
- Screwdriver
- Hammer and Chisel or a Small Sledgehammer
- Safety Glasses and Work Gloves
- Shop Vacuum or Bucket and Sponge
- Rags or Old Towels
- Drill With Masonry Bit
- Concrete Screws or Anchors
- Level
- Caulking Gun and Bathroom-safe Caulk
8 Simple Step-By-Step Guidelines on How to Replace a Toilet Flange on Concrete
Step 1: Prepare the Work Area and Remove the Toilet
First, you need to prepare your bathroom for the task. Turn off the water supply to the toilet using the shut-off valve located on the wall behind it. Flush the toilet to empty the tank and bowl, then use a sponge or shop vacuum to remove any remaining water. Disconnect the water supply line from the tank. Place old towels around the base of the toilet to catch any spills.
With the area prepped, you can remove the toilet. Start by unscrewing the nuts from the closet bolts at the base of the toilet, which may be hidden under plastic caps. Gently rock the toilet side to side to break the wax seal. Once it’s loose, lift the toilet straight up and set it aside on a protected surface, like a large piece of cardboard or an old blanket. This is a two-person job, as toilets are heavy and awkward to handle.
Step 2: Remove the Old Wax Ring and Assess the Flange
With the toilet out of the way, you’ll see the old wax ring and the toilet flange. Use a putty knife to scrape away all the old wax from both the flange and the bottom of the toilet. This can be a messy job, so take your time to clean the area thoroughly. A clean surface is essential for creating a good seal with the new wax ring later on.
Once the wax is gone, you can get a clear look at the old flange. Inspect it for cracks, breaks, or corrosion. Check how it is secured to the concrete floor. Some flanges are screwed directly into the concrete, while others might be set into the concrete itself. Understanding how the old one is installed will help you plan its removal and the installation of the new one.
Step 3: Detach and Break Out the Old Flange
If the old flange is screwed into the concrete, simply use a screwdriver or drill to remove the screws. If the screws are rusted or stripped, you may need to use a drill to bore them out. If the flange is a metal ring set directly into the concrete, the removal process is more intensive. You will need to carefully break it apart to remove it from the drainpipe.
Using a hammer and chisel, carefully start chipping away at the old flange material. Always wear safety glasses during this step to protect your eyes from flying debris. Work your way around the ring, breaking it into smaller pieces that you can pry out. Be very careful not to damage the PVC or cast-iron drainpipe underneath. Once the old flange is completely removed, clean up all the debris from around the drainpipe opening.
Step 4: Clean and Prepare the Drainpipe and Concrete Surface
After removing the old flange, it’s crucial to prepare the area for the new installation. Use your putty knife and a wire brush to clean any remaining sealant, wax, or debris from the top of the drainpipe and the surrounding concrete floor. A perfectly clean and smooth surface ensures a solid, leak-proof connection for the new flange.
Next, stuff a large rag into the drainpipe opening. This important step prevents sewer gases from entering your home while you work. It also stops tools, debris, or hardware from accidentally falling down the drain, which could cause a major plumbing blockage. Just remember to remove it before you install the new toilet.
Step 5: Position and Test-Fit the New Flange
Now it’s time to position your new toilet flange. Place it over the drainpipe opening, ensuring it sits flush and level with the finished floor. The bottom of the flange should fit snugly inside or around the drainpipe, depending on the model you purchased. Use a level to check that the flange is perfectly horizontal across its diameter in multiple directions.
An improperly leveled flange will cause the toilet to rock and will likely lead to leaks. If the flange isn’t level due to an uneven concrete surface, you may need to use plastic shims underneath it to achieve a level position. The goal is for the top surface of the flange to sit on top of the finished floor, not below it. If it sits too low, you might need a flange extender.
Step 6: Mark and Drill Holes for the Anchors
Once you are satisfied with the position and level of the new flange, it’s time to mark where you will secure it to the concrete. Use a permanent marker or pencil to trace through the screw holes of the flange onto the concrete floor. After marking the spots, remove the flange so you have clear access for drilling.
Using a drill equipped with a masonry bit that matches the size of your concrete screws or anchors, carefully drill holes into the marked locations. Make sure to drill to the depth recommended by the manufacturer of the screws you are using. After drilling, use a shop vacuum to clear away all the concrete dust from the holes and the surrounding area. A clean hole allows the anchor to set properly and securely.
Step 7: Secure the New Flange to the Concrete
With the holes drilled, you can now permanently install the new flange. Apply a bead of silicone caulk to the underside of the flange where it will meet the concrete. This creates an extra layer of protection against moisture. Carefully place the flange over the drainpipe, aligning its holes with the ones you drilled in the floor.
Insert the concrete screws or anchors into the holes and tighten them firmly with your drill or a screwdriver. Alternate tightening the screws to ensure the flange is pulled down evenly and remains level. Do not overtighten, as this could crack the flange or the concrete. Wipe away any excess caulk that squeezes out from under the flange for a clean finish.
Step 8: Install the New Bolts and Wax Ring
The final step before reinstalling the toilet is to set the new closet bolts and wax ring. Slide the new bolts into the slots on the flange, positioning them parallel to the back wall. You can use the plastic washers included with the bolts to hold them in an upright position. Make sure they are aligned correctly with the holes on the base of your toilet.
Next, place the new wax ring over the flange. You can either press it firmly onto the flange or place it on the outlet at the bottom of the toilet. Many prefer placing it on the flange itself. Remember to remove the rag from the drainpipe before proceeding. With the bolts and wax ring in place, you are now ready to carefully lower the toilet back onto the flange, reinstall it, and reconnect the water supply.
Following these steps on how to replace a toilet flange on concrete will ensure that your toilet is securely and properly installed. It is important to regularly check the condition of your toilet flange to avoid any potential leaks or damage to your bathroom flooring. If you notice any issues with your toilet flange, it is recommended to replace it as soon as possible.
Safety Tips
When working with plumbing and concrete, safety should always be your top priority. Always wear heavy-duty work gloves to protect your hands from sharp debris and rough surfaces. Safety glasses are non-negotiable, especially when chipping away at the old flange or drilling into concrete, as small fragments can easily cause eye injury.
Ensure your work area is well-ventilated to avoid inhaling sewer gases or concrete dust. Finally, lifting a toilet can strain your back, so bend your knees and lift with a partner if possible.
Common Mistakes to Avoid
One common mistake is not cleaning the area thoroughly, leaving old wax or debris that prevents a good seal. Another error is failing to ensure the new flange is perfectly level, which results in a wobbly toilet. Also, be careful not to overtighten the concrete screws, as this can crack the new flange.
Forgetting to remove the rag from the drainpipe before setting the toilet is a critical error that will lead to an immediate clog. Finally, avoid damaging the drainpipe itself when removing the old flange.
When to Call a Professional?
While this is a feasible DIY project, there are times when calling a professional plumber is the best choice. If you discover that the drainpipe itself is cracked or broken during the removal process, stop immediately and call for help. If the subfloor or surrounding concrete is severely rotted or damaged from a long-term leak, a professional will need to assess and repair the structural issue.
Additionally, if you are uncomfortable with any part of the process, especially breaking out an old metal flange, it’s wise to hire a licensed plumber to ensure the job is done correctly.
Frequently Asked Questions
Q1: Can I Use a Repair Flange Instead of a Full Replacement?
A1: Yes, in some cases, a repair flange or a spacer ring can be a viable solution. If the original flange is only slightly cracked or sits too low below the finished floor level, a repair ring can be screwed on top of it. This saves you the difficult step of breaking out the old flange. However, if the original flange is severely broken or corroded, a full replacement is the only reliable, long-term solution.
Q2: What Type of New Flange Should I Buy?
A2: The best type of flange depends on your drainpipe material. If you have a PVC drainpipe, a PVC flange is the standard choice. If you have a cast-iron pipe, you can use either a cast-iron flange or a PVC flange designed to fit inside it. Consider a flange with a stainless steel ring, as it offers better durability and resistance to corrosion and cracking over time compared to all-plastic models.
Q3: Does the Toilet Flange Need to Be Glued to the Drainpipe?
A3: Whether you need to glue the flange depends on the type you buy and your local plumbing codes. Some “push-tite” or compression-style flanges are designed to create a seal just by being pushed into the pipe. However, for a PVC flange on a PVC pipe, it is best practice to use PVC primer and cement to chemically weld the two pieces together, creating a permanent, watertight bond before you secure it to the concrete.
Q4: How Do I Know if the Flange Is at the Correct Height?
A4: The ideal height for a toilet flange is for its bottom surface to sit directly on top of the finished flooring. This means if you lay a straight edge across the flange, it should be resting on the tile, vinyl, or wood around it. If the flange is below the floor level, you may need a flange extender or a thicker wax ring to ensure a proper seal and prevent leaks.
Conclusion
Replacing a toilet flange on a concrete floor is a detailed task, but it is well within the reach of a determined DIYer. By following these steps on how to replace a toilet flange on concrete carefully, you can fix a leaky or unstable toilet and protect your home from water damage.
Remember to prioritize safety, take your time with each step, and never hesitate to call a professional if you run into unexpected complications. With a new, securely installed flange, your toilet will be stable and leak-free for years to come.