By Tom Scalisi and Steffani Cameron | Updated Jun 2, 2022 12:50 PM
In cramped bathing quarters that rely on a walk-in shower instead of a full-size bathtub, the shower pan can be an unsung hero. Its role? Protecting your subfloor from water damage by aiding drainage. This waterproof floor covering, which is often made of fiberglass, acrylic, or tile, slopes just enough to direct water toward the drain in the floor. When installed and maintained properly, it eliminates most problems caused by lingering water, from mold and mildew growth to structural issues like wood rot.
Whether you’re remodeling a bathroom to add a shower where it didn’t exist before, replacing a bathtub with a shower, or you’re replacing one that’s at the end of its service life, basic plumbing skills and a free weekend are all that experienced DIYers need when learning how to install a shower pan.
Many homeowners choose a shower (and thus a shower pan, because you can’t have one without the other) over a bathtub when renovating in order to increase the available floor space and make the bathroom feel larger. Walk-in showers tend to be sleeker in style than boxy or bulky bathtubs, and the glass walls that often enclose them contribute to an airier, less cramped aesthetic.
In terms of actual dimensions, a shower pan can be as narrow as 27 inches, making it much easier to squeeze into a floor plan than a standard 60-inch by 30-inch tub. Even those few inches regained by switching out a standard tub for a shower can make a cramped bathroom feel roomier.
In addition, the range of shower pan sizes and shapes allows great flexibility in placement. Awkward corners and walls that are too short to fit the average length tub can often accommodate a shower pan, be it prefabricated or custom-made. Because of the flexibility that showers can offer, homeowners are more likely to achieve an optimal layout that makes the most of limited space in a bathroom.
Last but certainly not least, the accessibility a shower affords makes it an attractive remodeling choice. The low, 3- to 4-inch threshold of a shower pan as well as helpful features like shower rails make bathing simpler for homeowners who are aging in place or who have to contend with limited mobility. Plus, if down the line a shower seat or bench becomes necessary, the relatively flat surface of a shower pan is more conducive to sitting than the curved bottom of a tub.
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Are you wondering how to select a shower pan for a space where there was no shower before? Prefab options certainly simplify the process. These models, available online and in big-box hardware stores, range from 27 to 66 inches in width, so there’s a pretty good chance you’ll find one that fits the configuration of your bathroom. Should that turn out not to be the case, you can get just what you need with a custom shower pan made from concrete, stone, or tile. When selecting an appropriate pan, whether prefab or custom, it’s important to consider the following.
A shower pan can’t necessarily take up all the available space in a bathroom corner. When determining the right pan size, you also need to account for the space required by whatever door you select for the shower enclosure. Consider the variety of shower doors and stalls available: sliding versus swinging, corner door versus side door, or perhaps no door at all. In Europe and Mexico, it’s popular to skip the door altogether, either hanging a curtain to contain splashes or leaving the shower area open and placing a drainage hole in the bathroom floor to draw away overspray.
Each type of door has its pros and cons. A swinging door requires enough clearance outside the shower for it to open without hitting a toilet or other fixture—and this may mean that there will be a little less square footage available for the shower stall and pan. A sliding door, on the other hand, requires enough space to retract, so one side of the pan needs to be double the width of the door. The third option, eliminating the door completely, offers the most flexibility in cramped spaces, but at the price of having to deal with overspray every time you take a shower. Either way, you have to nail down the door style before you can be certain how much floor space is available for the shower pan.
It may seem obvious, but beyond the constraints of the room, a big factor in determining shower pan size is you. How wide are you? How much room do you need to comfortably lather up and rinse off? If you’re a former linebacker, you’ll need a much larger shower space than, say, a 5-foot-3-inch gymnast. To get an idea of how much room you need, try out your best “YMCA” dance moves in the potential space.
As mentioned, your space may dictate whether you can buy something prefabricated or whether you’ll need a custom shower base. For example, sometimes the perimeter of the bathroom juts in so that a standard shower pan won’t fit, or you just can’t find a suitable shower pan in the length you need.
But this choice isn’t only about necessity; aesthetics also factor in. Most store-bought shower pans feature acrylic, fiberglass, or porcelain finishes in a neutral hue, while custom creations in such materials as concrete and tile encourage a little more creativity in execution and appearance. A custom shower—a renovation that can boost a home’s resale value—can certainly be left to the pros, but it could also be a DIY job for a homeowner who is comfortable working with concrete or mortar and tile.
It’s important to follow the manufacturer’s instructions for a prefab pan to a T, but their installation directions will likely be similar to the below steps. Even though custom shower pans vary widely from one installation to the next, they share many of the same installation considerations that apply to store-bought models.
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The subfloor needs to be in good shape before a shower base installation starts. If there is any damaged plywood or rot, it’s important to take care of that first. Also, check for any lumps and bumps that the shower’s space might contain.
Many shower pans have feet that support the majority of the weight while maintaining a slope. Use a tape measure and pencil to measure and mark the locations of these feet on the subfloor, and then use shims placed on the shower floor to create a level space for the pan. Composite shims are best for this since they are impervious to water and have greater load bearing capacity.
If the shower does not have feet, it will require a bed of sand and mortar mix. The mortar will eliminate the need to shim the pan.
Next, dry-fit the shower pan into place. This step serves several purposes. First, it allows the DIYer to determine whether or not they need to move the drain piping by laying the new pan in place. This is often necessary, especially when moving to a large shower pan or switching from a tub.
This step also allows a DIYer to check that the shimming they did in the previous step was effective. Use a bubble level to check that the pan is sitting level. If it’s not, adjust the shims until the pan sits level. Once level, predrill the shims and screw them to the subfloor.
Then, mark the height of the shower pan’s flange on each stud. These will serve as reference marks during the final pan installation.
Unbox the shower drain flange and separate its parts. Place a bead of plumber’s putty underneath the rim of the drain flange and place it through the shower pan from the top. On the underside of the shower pan, place the rubber or foam gasket and then the paper gasket over the drain flange’s threads. Finally, place the nut on the threads and tighten the nut by hand before cinching it down with the pliers.
Pro Tip: Check the shower pan’s instructions. Some manufacturers recommend using silicone instead of plumber’s putty during a shower drain replacement or installation, as putty may affect a fiberglass shower pan.
Place the shower pan in the space. If the pan has feet, it most likely also has clips that hold it to the studs, or the manufacturer’s instructions may recommend drilling the flange and screwing it to the studs. Be sure that it’s level, and attach the shower pan to the flanges to hold it in place.
If the shower pan needs a base of mortar, mix the sand and mortar according to the manufacturer’s instructions. Pour this shower pan mortar onto the base and level it with a trowel. Carefully wiggle the shower pan into place until it’s level and aligns with the reference marks along the rim. Once in place, lay a bag of mortar in the middle of the pan to weigh it down and prevent it from lifting as the mortar dries.
Pro Tip: Don’t fill the entire subfloor with mortar or there won’t be enough empty space under the pan to compress the mortar.
Cut a short length of pipe and install the shower flange, securing it with the rubber compression ring included in most kits.
Head to the floor below the shower pan and gain access to the shower drain assembly (this may require cutting the ceiling’s drywall. There should be unobstructed access to the drain flange, the tailpiece, and the rest of the shower drain plumbing sticking through the floor.
Attach the existing plumbing to the tailpiece by sliding the compression fitting over the tailpiece and tightening it in place.
Once you’ve successfully fit the pan, attached the drainpipe, secured the shower drain flange, and made all connections according to the manufacturer’s instructions, run the shower once to inspect for leaks. It’s also wise to plug the drain for a minute while the water is running, then stop the water and see if the water level holds to make sure the pan’s not leaking anywhere. If everything looks good, the shower should be good to go.
Assuming it’s installed properly, a prefab shower pan should last a decade or more. As it nears the end of its lifespan, though, a shower pan can break down. To prevent a compromised pan from letting water permeate and damage the subfloor of your bathroom, keep your eyes open for these signs of excessive wear:
Learning how to install a shower pan might be more intimidating than it needs to be. With the right technique, a bit of know-how, and the correct products or materials, the job can go fairly smoothly. Ensuring that everything is level and supported as it should be is the most important part to prevent leaks. After that, all it takes is hooking up the drain and testing for leaks before enjoying a hot shower.
That’s a lot of information about installing a shower pan, but there may still be some lingering questions. The following includes answers to some of the most frequently asked questions on the topic.
A shower pan is the flooring section of a shower. Rather than a tub, a shower pan has a low curb and sloped floors that collect water and direct it to the drain.
For some shower pans, the answer is yes, you need mortar. In other cases, shims and clips will do the job. The best way to determine how to install your shower pan is to check the manufacturer’s instructions for the recommended installation method.
“Shower pan” and “shower base” are often used interchangeably, but they’re technically two different things. A shower pan is the part of the shower that the bather actually steps on. The shower base is the structure underneath (in the case of tile or concrete showers).
Shower pans don’t actually secure to the floor, but there are two ways to hold them in place.
Most shower pans can last 10 to 15 years before they begin to degrade. At that point, they may allow water to permeate into the floor below. Luckily, replacing a pan isn’t the toughest DIY job—most DIYers can handle the job with just a bit of plumbing experience.
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