How to Install a Shower Pan

by Michael Franco
Master bathroom in new luxury home

Installing a Shower Pan at a Glance

  • Step 1: Dry-fit pan
  • Step 2: Attach drain body to pan
  • Step 3: Prep shower base
  • Step 4: Let dry and check for leaks

You might be a homeowner if … your online searches now include the term “shower pan.” Shower pan: A phrase you may well have been unfamiliar with until recently embarking upon the planning stages of a shower renovation.

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What’s a shower pan? Can you install one yourself? How tricky is it, really, in the grand scheme of bathroom renos? And how much money can you save by tackling this project on your own instead of calling in the pros?

Do not fear; the answers to all these burning questions can be found below, along with a handy step-by-step guide to get you on the road to popping that shower pan into place faster than you can say: “Homeownership can be a pain in the tuchus!”

The Basics

A shower pan is essentially the floor of your shower. Typically constructed in preformed acrylic or fiberglass, all shower pans include a slight slope to direct water into your drain and away from your bathroom floors.

According to, the cost of a shower pan installation by professionals is between $1,000 and $2,000, with labor costs making up the majority of the price tag. That means you could save some serious cash by installing it yourself.

Although the concept of shower pan installation itself is pretty simple, installation does involve some critical logistical considerations, such as leveling to ensure proper drainage. These trickier aspects mean this project probably falls in the intermediate range of home DIY projects. You can certainly do it on your own, but make sure you’re up for a potentially challenging job.

Step 1: Dry-Fit the Pan

Before you begin any shower pan installation project, the first step is to make sure your shower pan fits in the shower alcove. Although you may have measured the space correctly, you should still always perform a dry fit of your shower pan just to make sure that the edge of the shower base is sitting level. Also, check here to make sure the corners are square and if the drain hole lines up correctly with the existing drain line. If it does not align, trace the hole on the subfloor, then use a jigsaw to cut around it.

Before you start cutting, be sure to check with the manufacturer’s instructions as to how large the drainpipe hole should be. Keep in mind that you’ll also need to relocate the drain line as well, which includes moving the shower’s P-trap and waste pipe to align with your new drain location. This can be tricky, so if you feel like you might be in over your head, make sure you call a pro before you get too far along.

If you’re wondering how to replace a shower pan in an existing shower stall, bear in mind that there could very well be a mortar base underneath the pan. In this case, you’ll need an electric rotary hammer drill to chisel off the mortar from the subfloor.

Step 2: Attach the Drain Body to the Pan

Once you’ve performed a dry fit of your preformed acrylic or fiberglass shower pan, insert the drain flange, also called the drain body, into the shower pan. Before you use any sealant, dry-fit the drain body to make sure it’s flush with the shower pan. If it checks out, apply a sealant like silicone caulk underneath the drain body’s rim. Once again, be sure to carefully check the manufacturer’s instructions to make sure you’re using the proper sealant. Some brands call for acrylic caulk or even plumber’s putty to properly seal the drain. Using the wrong material could cause problems down the line.

After you’ve applied the sealant, screw the drain body onto the pan tightly, wiping away any excess caulking. When the drain body has been tightly screwed on, be sure to install any gaskets or washers that were included in the drain assembly. Remember that all drain assembly kits vary according to the manufacturer, so be sure to check the instructions before securing your shower drain assembly.

Step 3: Prep the Shower Base

If you’ve ever wanted to know what goes under a shower pan, here’s your answer: a mortar shower base. Because it’s absolutely paramount that the shower pan sits on a surface that’s as level as possible, it’s almost always necessary to create a level mortar shower base for the pan to sit on. Even if your pan was level during your dry fit, a secure shower base serves several important functions that you don’t want to neglect.

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What’s the Difference Between a Shower Pan and a Shower Base?

Although they are often mistakenly interchanged, a shower pan and a shower base are actually two very different things. Shower pans are the actual floor of the shower, while shower bases are the substructure under the shower floor. Besides creating a level surface for your shower pan, bases also help to direct water into the drain and protect the walls and floors of the shower alcove from water damage.

In nearly all cases, a mortar shower base installation should be done prior to a shower pan installation. To install a shower base, place a thin plastic waterproofing membrane down onto the subfloor of the shower stall. Mix a bag of mortar to pour on top of the membrane, then level the base using a trowel and float. The ideal type of mortar to use for your base is thin-set mortar — the same type of mortar you might use under a tile floor. Your base should be roughly 1-inch thick, making for a firm shower floor.

Do I Need Mortar Under a Shower Pan?

The majority of shower pan manufacturers recommend installing a bed of mortar under your shower pan. Besides providing a satisfyingly hard floor for your shower, a mortar base will also protect your subfloor from water damage, mold and even rot. While laying a mortar base seems simple, it’s important to make sure you are doing it properly. Because preformed shower pans are designed specifically to direct water into the drainpipe, a mortar base must be perfectly level for the slope to work correctly. While most shower pans require a mortar base underneath them, it’s best to check the manufacturer’s instructions just to make sure.

Some pans include screws and brackets to fasten the pan to wall studs for extra security. If yours doesn’t include any and you’d like to get that extra bit of security, take four roofing nails and attach the flanges on the side of the shower pan to the studs of the wall. Do this after you set the pan in the thin-set mortar and the drain in the drain hole.

Step 4: Let the Base Dry and Check for Leaks

Once your pan has been set down, allow the mortar to completely dry. This usually takes anywhere from 24 to 48 hours. When the mortar is completely dry, turn on your shower and let it run for roughly 10 to 15 minutes. Look around the shower stall, examine the pan for proper drainage and check for any signs of leaks.

If all looks good and the drain passes the test, pat yourself on the back, congratulate yourself on a job well done and prepare to type something not home repair-related into your search browser for once. Feels good, doesn’t it?