Closet Flange Installation – Flush or Above?

A toilet is a necessity in any home, and proper installation is a must to ensure that it works well. Leaky, broken, or misaligned toilets are a hassle for everyone involved. A key component to toilet installation is the closet flange; the fitting that connects the toilet to the drain pipe underneath. Plumbers, builders, and other trade professionals are well-versed in the art of the closet flange, and usually have an opinion on the best way to install it.

There are two main ways in which the closet flange is typically installed: above the floor or flush (level) with the floor. At SUPPLY.com, our PROs typically prefer the first way; we’d like to give an overview of both so that you can decide which way is best for your particular bathroom situation.

Closet Flange Installation 1 – Above the Floor

Installing the flange above the floor is known to help prevent leaks – the height of the flange allows for enough wax to properly seal the flange in place and keeps water from escaping. This way also provides more room for accuracy; when the floor is installed after the flange, the alignment is more likely to be off, causing more space for leaks and shifting.

To start, there are several types of closet flanges available. Some are made of plastic, while some are made of metal. The advantage to a metal flange is the quality – these tend to break less easily and secure more tightly in place than plastic. Another factor to consider is a knockout flange, or a flange covering that can be removed after installation. A knockout is especially beneficial when building a new home; the covering keeps any debris from falling into the drainage pipe.

Once your flange is picked out and you’re ready to install it, the next step is to determine the best height. Remember, this option involves placing the underside of the flange above the finished floor. The recommended height is ¼” higher than the floor. A wax ring will need to be added, and this amount of space allows for the wax to fit snugly; if the flange is placed too high, it runs the risk of making the toilet wobbly. The flange is further secured by closet bolts that anchor it to the floor. We found this video by This Old House helpful for above-floor installation:

Closet Flange Installation 2 – Flush with the Floor

Though above-floor installation is considered the “right” way to fit a flange, some swear by attaching it level with the floor. The process is generally the same, but the flange is secured down before the floor is finished. In most cases, the floor of a bathroom is tiled, and in this case the tiling is done after the flange is installed. Since the flange stops at the surface of the floor, the wax seal is further down from the toilet itself. This may lead to more leaks over time; however, it also eliminates the possibility for a shaking toilet that results from a too-high flange.

This second way is typically thought of as easier, as it involves less interaction with cutting or working around the floor, and may be the best route for someone new to the plumbing game. It also may be a good option for a project that needs a toilet installed before the flooring is ready.

Closet Flanges on SUPPLY.com

If you’re in the market for a closet flange, the first thing you’ll look for will likely be the size; you’ll want to make sure that it fits to the toilet and the piping. At SUPPLY.com, we have a variety of sizes in the 3” to 4” range – many will work with multiple pipe sizes. Some are made of plastic, some are made of metal, and some are made of plastic with a stainless steel ring to add strength. This ProFlo closet flange fits over a 3” or inside a 4” pipe, is made of stainless steel, and has a test clap to keep the space covered while it’s being installed.

Though installing the flange above the finished floor is ideal, as long as it is installed correctly the most important takeaway is that the flange is a hidden but absolutely necessary part to the toilet. If it is not being used the right way, leaks and flooding could occur, or even an emission of harmful fumes. When it comes to building a new bathroom or renovating an old one, make sure to find the right closet flange for the space.

Shop all closet flanges on SUPPLY.com below or give our product experts a call at 888-426-2323 for additional information.