DIY: How to Install a Toilet Flange in New Construction

Whether you’re building a new home or plan a major overhaul of your existing bathroom, knowing how to install a toilet flange could come in handy. Similar to a sink flange, this plumbing component connects the toilet to the sewer drain pipe – a crucial connection when you come to think of it, considering the type of waste that gets flushed down the toilet. 

To install a toilet flange in new construction, you first have to make the soil pipe flush with the ground. Make sure the flange fits perfectly into the drainpipe, then install it by sealing the surface with PVC cement. Fasten the flange with stainless steel screws before installing your toilet.

How to Install a Toilet Flange on Concrete Floor

Installing a toilet flange on concrete floors could be challenging, mainly due to the floor’s hardness. A hammer drill and a multi-tool – or a similar cutting device – can make the flange easier to install. Let’s see how to do it.

1. Gather the necessary tools and materials

For installing a toilet flange on concrete floors, you’ll need: 

  • Hammer drill 
  • ¼-inch or ½-inch masonry drill bit
  • Multi-tool or angle grinder 
  • Screwdriver
  • Tape measure
  • Putty knife
  • PVC primer 
  • PVC cement
  • Tapcon screws
  • Rubber gloves

2. Measure and mark the bolt holes

Installing the toilet flange’s holes parallel to the wall behind the toilet is crucial if you don’t want the toilet to be misaligned. 

Before drilling, mark the points where you’ll fasten each bolt to the floor by placing the flange over the drain pipe stub-out.

Rotate the flange until the bolt slots are by the flange’s sides in relation to the wall behind it. Use a tape measure to make sure the slots are aligned. It is not recommended to use a level because the wall may not be straight. Hence, you should measure the distance from the wall to each bolt slot and position them in such a way that there is the same distance between each slot and the wall.

Mark the bolt holes on the floor with a pen or permanent marker. 

3. Drill the holes 

Set the flange aside and attach a ¼-inch masonry drill bit to a hammer drill (some toilets use ½-inch bolts; if that’s your case, use a ½-inch drill bit instead). Drill the bolt holes into each of the marks you made at a depth of about 1 ½ inch.

4. Prime and apply cement to the pipe and flange

Once the holes are drilled, clean the area from any debris and apply PVC primer to the soil pipe. Do the same with the flange. 

After you’ve primed each surface, apply PVC cement to the pipe and flange alike, then place the flange back into the stub-out. 

5. Install the toilet flange

Rotate the flange so that the bolt slots are parallel to the wall behind and centered with the holes you drilled earlier. When the flange is in place, press it down and wait for the cement to dry – PVC cement needs about 30 seconds to harden, so make sure to be fast during this step.

Once hardened, it will take another 15 minutes or so for it to set and at least two hours to fully cure. You can continue with the installation after about 15 minutes.

All you have to do now is secure the flange to the floor with Tapcon screws. You can now seal the flange with a wax ring and proceed to install the new toilet.

How to Install a Toilet Flange on Tile Floor

Installing a toilet flange on tile floors isn’t that different from installing a closet flange on concrete. However, you should make sure you’re using the right drilling technique to prevent damaging your floor.

1. Gather the tools and materials

One of the hardest parts in installing a closet flange on tile floors is drilling the tile without causing it to break or crack. The only way to do this is with the right drilling tool and drill bit. Here are the tools and materials you’ll need: 

  • Variable speed drill
  • Carbide drill bit (¼- or ½-inch)
  • Cooling oil
  • Screwdriver
  • Tape measure
  • Putty knife
  • PVC primer 
  • PVC cement
  • Tapcon screws
  • Rubber gloves

2. Measure and mark the bolt holes 

Follow the steps above to measure and mark the bolt holes. Remember that they should be perfectly parallel to the wall, or the toilet will look misaligned.

3. Prepare the drill bit

The main difference between installing a toilet flange on concrete or tile floors is the drilling. Drilling in tile requires you to prepare the drill bit to prevent overheating. No need to worry, though. Preparing the drill bit simply means dipping it in coolant oil before attaching it to the variable speed drill.

4. Drill the holes 

With the bit covered in coolant oil, set the drill to the lowest speed and place the tip of the drill bit perpendicularly onto the marked spot. Drill back and forth a couple of times to help the bit “bite” into the tile.

Once the drill bit has gripped onto the surface, start boring straight down at the lowest speed until you’ve passed through the tile. At this step, switch to the high-speed setting and continue drilling through the backboard and into the subfloor. 

If you notice the drill bit getting red at any point during the drilling, stop the operation, let the bit cool for a minute or two, and dip it into cooling oil before continuing. Repeat for all holes.

5. Install the flange 

Use PVC primer and PVC cement to install the flange, then fix it with Tapcon screws. You can now install the toilet.

How Do You Install a Toilet Flange on a Wood Floor

Hardwood flooring doesn’t create too many problems when it comes to installing a new toilet flange. In fact, it is much easier to install it on a wood floor compared to tile or concrete. Assuming you’re installing the flange directly onto the hardwood floor (not on the subfloor), here’s how to do it.

1. Gather the necessary supplies 

If you want to install a toilet flange on hardwood floors, you’ll need: 

  • Electric drill driver
  • Wood drill bit
  • #10 Phillips screws
  • Phillips screw bit
  • Plastic toilet shims or toilet base slab
  • Silicone caulk
  • Tape measure
  • Putty knife
  • PVC primer 
  • PVC cement
  • Rubber gloves

2. Install the flange

Installing the toilet flange requires you to follow the same steps highlighted in the methods above, but you must use a different drill bit to bore the holes.

After you’ve attached the drain pipe to the flange nipple with PVC cement, fasten the flange with Phillips screws and check the toilet’s stability by placing it on top of the flange. If you feel it is rather wobbly, you should use shims or install a toilet base slab to ensure stability once you attach the toilet to the flange with wax.

3. Seal the area

After you’ve placed the toilet on the flange and fastened it to the floor, you should seal the base with silicone caulk to prevent water splashes or spills from leaking under the toilet bowl. In this way, you can prevent the floor under your toilet from getting damaged.

Frequently Asked Questions

Does the toilet flange go inside or outside the pipe?

It doesn’t really matter. If both surfaces (flange nipple and drain pipe) are primed correctly, and you make sure the PVC cement is uniformly distributed with no holes or cracks, you can install the flange either on the outside or inside of the pipe without worrying that it will leak.

You can buy a larger-diameter drain pipe and install the toilet flange inside it if you’re a novice concerned about mistakes. However, if the rough-in plumbing is already installed and the closet flange is slightly larger, you don’t have to replace the pipe.

Pay attention during the installation phase to seal the surfaces correctly. In this way, the flange won’t leak.

Should the toilet flange be on the subfloor or the finished floor?

There is a lot of debate around this question, so, to shed some light on the matter, know that the flange should always go on top of the finished floor. That’s because the bottom of the flange needs to be in tight contact with the floor, while the toilet bottom and the top of the flange must be on the same plane.

This is impossible to achieve if you install the floor after installing the flange since the floor’s thickness won’t allow the toilet and the flange to sit on the same plane.

In addition to leaks, you also risk damaging the floors when tightening the toilet nuts if you decide to install the flange on the subfloor rather than the finished floor.

Should the toilet flange be flush with the concrete floor?

The toilet flange should never be flush with the floor, concrete or otherwise. As explained above, the flange should always be installed above the finished floor, allowing the toilet and flange top to be on the same plane. This is essential for a correct toilet installation.

Can the toilet flange be lower than the floor?

No, the toilet flange should never be lower than the floor. However, if you live in an older home and want to replace an old toilet, you may find that the past owners have installed the flange on the subfloor. You don’t have to make major changes if this happens. 

You could use a flange height adjustment ring. This rubber gasket creates a tight seal once you fasten the toilet bolts and nuts, allowing you to install the toilet without worrying about leaks.


Installing a toilet flange in new construction requires you to follow more or less the same steps regardless of the type of floor you have. There are slight differences for each floor type, though, so make sure to check out the right steps above. And don’t forget – the flange should always go on top of the floor for a correct installation.

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