How to Install a Toilet

In my new workshop/office area, the Rogue HQ, I knew I wanted running water, which meant I needed a drain and since I was doing that, I probably should just put in a bathroom as well. I had my plumber rough in all the underground plumbing before we poured the concrete slab. I planned on having him come out and install all the fixtures as well but he is currently on the run from the FBI (🙄 long story), so rather than call another plumber I decided it was time for me to learn a new skill. After a good amount of research I realized this was a fairly straightforward job and I was quite capable.

For this tutorial I go over all the steps, in detail, for how I installed my skirted toilet on a concrete slab. If you have a concrete slab and roughed in plumbing, this is going to align with your install very well. If you are installing over a plywood subfloor or finished floor this might differ a bit but I try to touch on that throughout.

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Disclosure: This project was sponsored by DAP Products however the information and opinions are 100% my own.

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Time needed: 1 day.

This tutorial is meant to serve as a guide for installing a toilet. While I try to cover some of the variations in different installation conditions, I did not cover them all. Nevertheless, always refer to the manufacturer specifications and your local plumbing codes, and if you don’t feel comfortable, hire a plumber.

  1. Installing the Toilet Flange

    Start by cutting the rough plumbing flush with the subfloor. For this, I used a reversible back saw. A pull saw would work great as well.

    How to install a toilet Step 1

    Now dry fit the flange and check the height. I can see this flange is about 1/2″ higher than the subfloor so some of the floor must be removed and the PVC cut down a bit further.

    How to install a toilet Step 2

    To cut the PVC I recommend a Dremel rotary tool with a cutting wheel. This will allow you to cut from inside the PVC. Plug the drain with a rag or something to catch any debris.

    How to install a toilet Step 3

    If you have a concrete slab like I do, then you will need a hammer and masonry chisel to remove some of the concrete. If you are deal with wood subfloor then a wood chisel or oscillating multitool will work well. You’ll need to remove enough of the floor so that the top of the flange will be level with the finished floor.

    How to install a toilet Step 4

    In this case, the concrete is my finished floor so ideally I would have recessed the entire flange into the concrete. Since I didn’t do that, I have to shim the toilet in a later step.

    How to install a toilet Step 5

    Vacuum up all the debris and fit the flange to the PVC. I used a press-fit style flange that has a rubber ring that compresses as it slides into the pipe to seal it off. These are way easier then having to cement a flange in place.

    Before anchoring the flange to the floor, make sure that it is oriented such that the T-bolts (included with the toilet) will be the same distance from the back wall when installed. This will make sure that the toilet is straight when mounted to the flange.

    How to install a toilet Step 6

    Anchor the flange with the appropriate fasteners. I used four 1/4″ x 1-1/4″ Tapcon screws, pre-drilling with the correct masonry bit first.

    How to install a toilet Step 7
    How to install a toilet Step 8

  2. Connecting the Supply Line

    This is probably the easiest part but can get messy if you don’t prep it right.

    First, you’ll need to locate and turn the main water line off. Then go to the nearest tub or faucet and turn the water on. This will release the pressure in the water lines and drain most of the water out, reducing the mess.

    Now it’s time to cut the roughed in water line. This can be done with a small handsaw but if you think you’ll ever do any plumbing projects again, I recommend picking up a flexible tube cutter. Also note that if you are connecting to copper you’ll need to cut it with a standard tube cutter.

    How to install a toilet Step 9

    When cutting the supply line make sure you leave enough to connect the toilet supply line and the escutcheon plate that will cover the hole in the wall.

    It’s a little more money but I highly recommend the 1-piece toilet supply line. This line has a 1/4 turn valve built-in and press-fit fitting that works with PEX, copper, or CPVC. So you just press one end onto the water line and screw the other end onto the toilet tank (not yet installed).

    How to install a toilet Step 13

    When pushing the fitting onto the PEX water line you may need to use a set of pliers or vise-grips to hold the water line in place.

    How to install a toilet Step 10

  3. Installing the Bowl

    Once the finished floor is in the toilet can now be installed. I am installing a skirted toilet which means the trap and mounting nuts will be hidden. The toilet I have came with some nuts that will tighten the t-bolts down on the flange and help them to stand up straight, making the next step a bit easier.

    How to install a toilet Step 14

    But before we can set the toilet we need to get the wax ring in place. The wax ring is exactly that, a thick ring of wax that gets pressed onto the bottom of the toilet around the hole.

    How to install a toilet Step 15

    Once the toilet is set in place the wax ring will compress (or spread out) and seal off that connection making sure no sewage gases leak out.

    How to install a toilet Step 16

    If the toilet has a little wobble in it that can be taken out with shims. Since my shims are in contact with concrete I used treated wood to resist rot.

    How to install a toilet Step 18

    The nuts then get tightened down to secure the toilet in place.

    How to install a toilet Step 19

  4. Mounting the Tank

    The tank can now be installed the back of the bowl. First place the rubber seal between the openings.

    How to install a toilet Step 20

    Then fit the tank in place and secure with the included hardware.

    How to install a toilet Step 21

    Most toilets will come with a tool to help hold the nut while tightening the tank. Tightened both bolts at the same time (alternating sides) so that they are even tightened and the tank will be level.

    How to install a toilet Step 23

  5. Connecting the Water Supply Line

    Now it’s time to attach the supply line to the tank. This connection screws on and can be hand tightened.

    How to install a toilet Step 25

    Turn the water valve on and check for leaks. If all is well, adjust the float in the tank so that the water shuts off approximately 3/8″ below the top of the overflow pipe.

    How to install a toilet Step 27

  6. Installing the Toilet Seat and Tank Lid

    The instructions for how to do this will probably vary between toilets. Mine came with two rubber plugs that fit into the holes and and expanded to secure themselves when the bolt was tightened up.

    How to install a toilet Step 30

    The lid simply sits on top of the tank.

    How to install a toilet Step 31

  7. Sealing the Base

    It is a code requirement to add a watertight seal around the base of the toilet. To do so I used DAP 3.0 Kitchen, Bath & Plumbing High Performance Sealant. The key features of this sealant and why I recommend it is that, not only does it have 10-year mold resistance but it also is specially formulated with Microban Antimicrobial protection to resist stains and odors.

    How to install a toilet Step 32

    Since I had to shim the toilet, I needed to install some foam backer cord to give the sealant something to flow against.

    How to install a toilet Step 33

    Then I laid down a thick bead of sealant, all the way around the toilet base.

    How to install a toilet Step 36

    One tip, when doing any kind of caulking like this, I recommend having a little cup of alcohol (for silicone caulk) or water (for latex caulk).

    How to install a toilet Step 37

    Wet your finger before using it to round-over the caulk or sealant. This will lubricate your finger to create a smooth joint as well as help prevent excess sealant from sticking to your finger.

    How to install a toilet Step 35

That’s it! I hope you now feel comfortable installing a toilet. I know this was a longer article with a lot of photos, but I wanted to cover every step in detail to show that this really is an easy job when you have the right parts and tools. Let me know if you have any questions in the comments.

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