How To Build A Shower Curb With A 2×4

Jessica Stone
by Jessica Stone

Installing a shower curb is essential to keep water contained and prevent it from spilling out of the shower area and onto the bathroom floor. A good and properly installed shower curb does all this and is entirely water-resistant. The waterproof nature doesn’t allow water to infiltrate the curb, increasing its overall lifespan.

As you might expect, there are a variety of methods and ways to build a shower curb. However, we are going to focus on durability and, more specifically, constructing a shower curb using 2x4s. 2×4 wood is very commonly used, easily accessible, and simple to cut, stack and place as the base for your shower curb.

The steps outlined below will help you to effectively and efficiently construct a shower curb out of 2x4s that is waterproof and built to last.

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Step 1: Construct the Shower Curb Base

The type of material that you use to form your base will largely depend on the flooring that you’re working on. However, 2x4s are very versatile and can work on multiple flooring types, aside from wood. You will be building the base for your shower curb by stacking two or three pieces of 2×4.

Measure the length of your shower entrance and cut the 2x4s to size. To create your curb, lay them out across the entrance and stack them on top of each other. Secure the 2x4s by screwing them to the floor and also to each other.

General Tips:

  • Double-check that the height of your curb will not interfere with your shower door.
  • If possible, use non-corrosive screws to secure the 2x4s.
  • Consider the height of your curb. If it’s too high, children (and possibly even adults) could trip when entering and exiting.
  • Avoid using treated wood as it contains moisture and will eventually shrink.

Step 2: Position the Liner

In order to ensure that your wooden curb is properly protected from water, you want to use a water-resistant and flexible pan liner. Before laying the liner, remove the top piece of the drain flange and replace the bolts connecting it to the bottom half.

Position the liner across your bathroom floor so that it evenly runs up the walls of your bathroom. It should reach about seven to eight inches from the floor and will ultimately be covered up by wall panels.

The liner should be placed in a manner that completely covers your wooden curb and extends out onto the bathroom floor. During installation, use special care to not puncture the liner and create the possibility of future leaks.

General Tips:

  • Before purchasing your liner, take the proper measurements.
  • For safety, buy more liner than you need.
  • If your liner is too stiff to lay, you can expose it to some heat for easier maneuverability. Simply putting the liner in contact with some sunlight can make it easier to manage.

Step 3: Cut the Drain Hole

It’s especially important that this step is done with care as cuts made to shower liner is irreversible. If done incorrectly, you’ll have to purchase an entirely new piece. Steady hands and a sharp utility knife are all you need for the most precise cut.

Inspect with your hands for the shower drain and puncture a hole right in the center. Move in a circular motion to cut out the liner until you reach the four bolts indicating the bottom piece of the drain flange.

Unscrew the four bolts and waterproof your drain by inserting a ring of silicone underneath your liner and positioning it on the bottom section of the flange. Press the shower liner down onto the silicone ring until it is flush against the surface. Replace the top part of the drain flange and screw gently to secure. Do not screw too tightly, as you could crack the plastic drain flange.

Step 4: Secure the Liner

Next, you’ll want to place the liner carefully into the corners of the shower floor and curb. Position the edges up the side of the wall and use either tape or nails to hold them in place. Fold the liner onto itself in the corners that are opposite to the curb.

At the curb edges, cut where the curb connects with the wall and lay the flag of the liner over the curb, making sure to cover it completely. If it isn’t completely covered, you risk water leaking through the corners. For added protection against water, hold the liner in place with pan glue. Glue carefully, as it dries fast and you will only get one shot at it.

General Tips:

  • Make sure to use the proper glue that is intended for use with liners.
  • To avoid air pockets, press the liner up against the curb on the outside and inside, using another 2×4.
  • On the outside of the curb, drive screws into the wood to hold it in place. However, do not pierce the liner on the top or inside of the shower area.

Step 5: Install Metal Lath

While you can always opt to nail planks of wood around the curb, you can have the ultimate assurance of no leaks by covering the curb with metal lath. You will add the lath over the top of the curb and then cover with a layer of cement.

Measure the area to determine the appropriate amount of lath you’ll need and then cut it minus one inch. You don’t want the material to be too tight on the liner and cause holes. Cover the curb with the lath and bend it into position.

To get the perfect shape, use another 2×4 to bend the lath around it. Secure the metal lath by nailing it in place on the outside of your curb.

General Tips:

  • To prevent the metal lath from piercing the liner, cover the edges with tape.
  • Lath edges are very sharp. Wear gloves to protect your hands.
  • For a stiffer curb, you can overlap multiple pieces of lath on top of each other.

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Step 6: Finish Off with Cement

The final step is to apply cement mortar over top and successfully finish up the base of your shower curb. Pre-made mortar can be purchased from any home improvement center and then mixed with the appropriate amount of water. However, you can create your own mortar by combining 4 parts sand, 1 part masonry lime, 1 part Portland cement and water.

Spread the mortar over the curb so that it is about one inch high. Then, place a straightedge on top and press down to create suction. With the straightedge still in place, add ¾ inch thick of mortar to the outside of the curb. Utilize the straightedge to keep your measurement consistent.

As you apply, gently press the mortar to keep it in place. Any excess can be removed using a flat trowel. After you’ve finished scraping the outside, move to the inside and repeat the process with the same thickness of material.

Allow the mortar to set and dry for about an hour before doing the finishing touches with your flat trowel. Make sure that the inside and outside of the curb are parallel and then install your finishing tile to the sides, wait thirty minutes, and then tile the top.

Quick Tip: You can add some water to your straightedge and flat trowel to prevent mortar from sticking to it.

Jessica Stone
Jessica Stone

Jessica considers herself a home improvement and design enthusiast. She grew up surrounded by constant home improvement projects and owes most of what she knows to helping her dad renovate her childhood home. Being a Los Angeles resident, Jessica spends a lot of her time looking for her next DIY project and sharing her love for home design.

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