Bathtub/shower combos have been a popular option for years, but the aesthetic of a walk-in shower is quickly becoming a more appealing option for many homeowners. Small walk-in shower stalls will typically have a plastic base and glass walls that are pre-fabricated for a quick installation. These products generally come with a square or circular center drain that measures about 3 to 4 inches in size.
Medium to large walk-in showers don't usually have a pre-fabricated base. Instead, the floor of the shower is made of mortar and tile. While this process takes longer than installing a pre-fabricated floor, it also gives you the freedom to make the shower look the way you want. Replacing the usual center floor drain with a linear shower drain is a great way to increase the appeal of your new shower while simultaneously enhancing the functionality of the design.
Just keep in mind that you need the skills and experience to install a new shower completely from the plywood subfloor to the finished tile in order to tackle this project. If you have the skills, experience, and time to handle this DIY job, then keep reading to learn how to install a linear shower drain.
What Is a Linear Drain?
While a center drain has a small square or circular drain opening, a linear drain consists of a long drain trough that typically runs along the back wall of the shower, parallel to the opening of the shower. The trough empties into an unseen central drain connected to the drainpipe for the shower. Linear drains can have metal covers, like traditional center drains, but they may also have covers that match the color and appearance of the surrounding tile so that the drain can blend into the aesthetic instead of sticking out.
Before You Begin
Installing the floor, linear drain system, and tiles will take several days, even if you are working quickly because the mortar needs time to properly dry, so it's important that the bathroom isn't used during this time. If you don't have a second bathroom with a shower, then it's recommended to find a different place to stay for a few days or at least plan a place, like a friend's home, to have a shower when necessary.
Additionally, you will want to clean the area thoroughly before starting. This helps prevent dirt and dust from obstructing the adhesion of the mortar, grout, and silicone used during the process. Most municipalities do not require you to have a permit for installing a new shower, but if you are updating the drain lines, you may need one. Make sure to check your local building codes and get permits, if necessary.
Equipment / Tools
- Tape measure
- Hole saw bit
- Utility knife
- Wire cutters
- Mixing paddle (optional)
- Tile wet saw or tile cutter
- Grout float
- Grout sponge
- Linear drain assembly
- Base drain
- Tar paper
- Wire lath
- Drain glue
- Shower pan mortar mix
- Waterproof shower pan liner
- Silicone caulk
- Pea gravel
- Thinset mortar mix
Measure and Mark the Drain Location
The first step in the process is to use a tape measure to measure the location for the drain and mark where you want it to be installed. Typically, linear shower drains are installed in four different ways, including one-sided wall-mounted, three-sided wall-mounted, free floor-mounted, and shower entrance floor-mounted.
- One-sided wall-mounted is the most common option. It refers to the drain running along one side of the back wall in the shower. The ends of the drain do not extend all the way to the side walls of the shower.
- Three-sided wall-mounted drains are the same as the one-side wall-mounted drain except that the ends of the drain do extend to the side walls of the shower, coming into contact on three sides instead of just one.
- Free floor-mounted linear drains are positioned in the middle of the shower, instead of touching any walls.
- Shower entrance floor-mounted linear shower drains run across the shower entrance between the two shower walls, as indicated by the name.
Depending on your selected style, you may need to relocate the current drain lines. Keep in mind that floor-mounted drains do not have as much support as wall-mounted drains.
Calculate the Drain Height and Cut a Drain Hole
One of the goals during the installation of a linear drain is to ensure that the top of the grate cover on the drain will be perfectly level with the surrounding tile. To achieve this goal, you need to calculate and measure the drain height so that the top of the drain will sit 1/16-inch below the adjacent tile before the grate cover is added.
It's a good idea to measure the height of the linear drain assembly with the grate cover and without the grate cover so that if the difference is greater than or less than 1/16-inch, you can make the adjustment to the height during installation so that the floor ends up level with the drain.
Use a drill with a hole saw bit to make clean, precise circular cuts through the plywood if you need to relocate the drain line. It's recommended to make a 3 1/2-inch hole and position the center of the drain about 2 1/2 to 3 inches from the back wall.
Slide the base drain into the drain line and insert the linear drain to take an accurate height measurement. Mark the desired height on the shower wall, then remove the linear drain and base drain.
Install Tar Paper and Wire Lath
Use a utility knife to cut tar paper so that it can cover the plywood subfloor. Make sure that it also covers the corners and the base of the shower walls. This tar paper layer will prevent the plywood floor from absorbing any moisture from the shower pan mortar mix.
You can also cut a sheet of wire lath with a set of wire cutters so that it can lay on top of the tar paper and help provide stability for the shower pan mortar mixture.
Connect and Insert the Base Drain
Before adding the shower pan mortar mix, cut the wire lath and tar paper so that the base drain can be inserted into the drilled hole and reconnected to the drain line. Make the sure drain is properly aligned and level according to the desired installation location.
Pour some water into the base drain to make sure that there aren't any leaks between the base drain and the drain line. The fit should be tight enough that you don't need drain glue, but if you are concerned about the connection, apply drain glue to seal the parts together.
Create a Sloping Floor
This process starts with the pre-pan mortar mix. Use a bucket and a shovel to mix the mortar, or consider using a mixing paddle to make the job easier. Add the mortar on top of the tar paper and wire lath, but do not cover the base drain.
Level the pre-pan mix, keeping in mind that for the water to properly drain from the shower, it's important to create a floor that slopes on a gradient of about 1 to 2 degrees or a slope of about ¼-inch per foot towards the drain. Use a bubble level to make sure that the gradient is correct.
When the pre-pan mortar is flat and leveled appropriately, leave the mortar to set for about 24 hours.
Install Waterproof Liner and Clamping Ring
Waterproof shower liners provide a significant layer of protection against water damage, rot, and unseen mold growth, so the next step in the process is to cut and install a waterproof liner on top of the pre-pan mortar. The liner should extend at least 6 inches up the sides of the shower wall to create an effective water barrier.
You can use nails or screws to fasten the edges of the liner to the walls to prevent it from sliding down out of position. Cut a small slit in the liner over the bolts on the base drain, then push the liner over the bolts to keep the liner in place. Cut a hole through the liner the same size as the opening of the base drain, then secure the clamping ring to the base drain to hold the liner in place and create a watertight seal.
Add the Top-Pan Mortar and Tiles
If you covered up your initial height marker, now is the time to measure and mark the height again. Use your bucket and shovel to mix the top-pan mortar mixture, then connect the linear drain to the drain base and check to make sure the drain is level. Linear drains typically come with adjustable drain feet that can slide under the edges of the drain to make sure it's level.
Pour the top-pan mortar onto the waterproof liner and fill the liner, leveling the mortar to maintain the gradient of about 1 to 2 degrees or a slope of about ¼-inch per foot towards the drain. Make sure to leave enough room for the final thinset layer and tile application.
Finish installing the shower tiles and ensure that the top of the linear drain is 1/16-inch below the top of the adjacent tiles when the job is complete.
Seal the Drain and Place the Grate Cover
With the shower installation finished, the last step is to seal the joint between the tiled floor and the drain with a bead of silicone caulk, then add the linear drain floor grate cover. If done correctly, the 1/16-inch height difference should be made up with the installation of the grate cover, giving you a perfectly level shower floor.
When to Call a Professional
Installing a linear drain isn't a job that is limited to just installing the drain. You may also need to be able to lay mortar on a specific angle, run and connect drain lines, cut and install tile, and seal the entire shower to prevent water damage, rot, and mold growth. While a skilled, experienced DIYer can handle this job, it may be outside of your skill set or you may just not have the time. Consider hiring a professional to ensure that this job gets done right the first time so that there aren't any problems in the future and you are happy with the end result.