How to Waterproof a Shower
Wall in the shower area., Mark off the area you want to waterproof., Cut a roll of reinforcing membrane to fit over the walls., Create openings to accommodate the shower fixtures., Apply a coat of liquid waterproofing to the backing board., Press...
Step-by-Step Guide
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Step 1: Wall in the shower area.
If you’re in the process of building the entire bathroom from scratch, you’ll need to start by laying the foundation for the walls around what will be the shower stall.
To do this, you can install cement or fiber backing board.
The rest of the waterproofing materials will be applied directly to this wall backing.Another option is to put in ordinary drywall, then cover it with mortar to provide a layer of water-resistant protection.
Even though materials like concrete backing board are designed not to swell, split or mold when they come into contact with moisture, it’s highly recommended that you take the time to treat them with liquid waterproofing to ensure that they’ll last. -
Step 2: Mark off the area you want to waterproof.
Measure the shower stall and use a pencil to mark the exact dimensions along the backing board.
Then, run a strip of painter’s tape along the markings you made to create an outline.
This will make it clear where the waterproofing materials are needed.It’s a good idea to extend your waterproofing an inch or so beyond the boundaries of the shower stall itself, just to be on the safe side. , First, measure and trim the membrane to fit the flat sections of the walls, marking to indicate where key fixtures like the valve, shower head and temperature knobs will be situated.
Cut the membrane into long, thin strips to fit the corners where the shower walls meet.Reinforcing membranes are typically made from tightly-woven fibers.
When sandwiched between layers of liquid waterproofing, they’ll provide an additional layer of water-stopping protection.Leave 2-3 between the membrane and the corners and edges of the shower stall.
A little blank space will make it easier to waterproof these areas separately later on. , Once you've modified the membrane to the appropriate size, cut a large X-shaped slit in each of the spots you marked.
When it comes time to install the fixtures later on, you'll be able to easily fit them into place over the membrane without losing an inch of waterproofing surface area.If you already have a showerhead, faucet and knobs picked out, measure them around the base before you cut the slits so you don't have to make them any bigger than necessary.
Do your cutting with an Xacto or craft knife, and place the membrane on a hard, flat surface that you don't have to worry about scarring up. , Brush the waterproofing over the entire wall using a roller or handheld brush.
Make sure it forms a thick, even coat, with no obvious gaps or bare spots.Paint-on waterproofing products contain liquid rubber, which both acts as an adhesive for the membrane and a forms a bond that’s too tight for moisture to penetrate., Carefully position the precut membrane and stick it to the wall by hand, starting at the top.
Once it’s secure, go over it a few times using the flat side of a trowel to work out any creases or air bubbles.
You may need to use a liberal amount of waterproofing in order to get the membrane sheet to stick.
To help the membrane conform to the corners of the stall, try folding the strips in half widthwise or scoring the backside lightly so that they sit at a 90 degree angle. , Apply the second coat directly over the reinforcing membrane.
By the time you’re finished, the brightly-colored membrane should no longer be visible underneath.Avoid totally covering up the valve and fixture sites.
You’ll need to be able to find these later once it comes time to install the finished surface.
Brush on the followup coat in the opposite direction of the initial coat.
For instance, if you used vertical strokes to apply the first coat, use horizontal strokes for the second one.
This will help create a better seal. , Depending on the size of the shower and the thickness of the adhesive, this may take several hours.
In the meantime, be careful not to touch the materials.
Doing so may wear down the waterproof coating or cause the reinforcing membrane to come loose.
It may be a good idea to begin your project in the afternoon or evening, then wait until the following day to complete it. , Set the sloped tray on top of the subflooring at the base of the shower stall.
If your shower’s floor pan comes in multiple sections, make sure they’re properly aligned and locked before moving on.
Use the circular template included with the installation kit to make a small mark or notch in the subflooring where the drain will be centered.Be sure to arrange the opening for the drain on the same side that the showerhead will be on.
Floor trays are included in most shower installation kits.
They are typically sold pre-sized and ready to go. , Remove the floor tray and find the place where you marked the drain.
Fit an electric drill with a 4” hole saw attachment.
Place the drill head flush against the subflooring and begin drilling, applying constant pressure all the way through.When you’re done, wipe the subflooring with a damp cloth to pick up any sawdust that’s collected nearby. , Brush on the waterproofing the same way you did with the walls.
Aim for a thick coat and even coverage.A handheld brush will be your best bet for applying the waterproofing to the floor. , In addition to the tray itself, you’ll need to lay strips over the cracks where the floor and walls connect.
Afterwards, measure and cut a large hole to fit precisely over the drain opening.
Finish by applying one last coat of waterproofing over the entire floor.If the membrane you’re using isn’t large enough to cover the floor in one piece, you can trim and overlap multiple sections to get just the right size.
For showers with sliding doors, place a strip around the lip of the stall where you enter., Once the materials have had time to set up, they’ll prevent water from seeping into the wall behind and beneath the shower stall.
You’ll then be ready to install eye-catching tile or a vinyl or acrylic liner.
Enjoy a hot shower as a reward for a job well done!Perform at least one one “flood test” when you’re finished to determine whether you’ve waterproofed all parts of the shower stall successfully.
Don’t forget to later set the drain, showerhead and other fixtures in the openings you left for them. -
Step 3: Cut a roll of reinforcing membrane to fit over the walls.
-
Step 4: Create openings to accommodate the shower fixtures.
-
Step 5: Apply a coat of liquid waterproofing to the backing board.
-
Step 6: Press the reinforcing membrane into place.
-
Step 7: Brush on an additional coat of waterproofing.
-
Step 8: Allow the waterproofing to dry completely.
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Step 9: Install the floor tray.
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Step 10: Drill a hole for the drain.
-
Step 11: Spread waterproofing over the floor tray.
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Step 12: Smooth reinforcing membrane over the floor and surrounding areas.
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Step 13: Let the waterproofing dry.
Detailed Guide
If you’re in the process of building the entire bathroom from scratch, you’ll need to start by laying the foundation for the walls around what will be the shower stall.
To do this, you can install cement or fiber backing board.
The rest of the waterproofing materials will be applied directly to this wall backing.Another option is to put in ordinary drywall, then cover it with mortar to provide a layer of water-resistant protection.
Even though materials like concrete backing board are designed not to swell, split or mold when they come into contact with moisture, it’s highly recommended that you take the time to treat them with liquid waterproofing to ensure that they’ll last.
Measure the shower stall and use a pencil to mark the exact dimensions along the backing board.
Then, run a strip of painter’s tape along the markings you made to create an outline.
This will make it clear where the waterproofing materials are needed.It’s a good idea to extend your waterproofing an inch or so beyond the boundaries of the shower stall itself, just to be on the safe side. , First, measure and trim the membrane to fit the flat sections of the walls, marking to indicate where key fixtures like the valve, shower head and temperature knobs will be situated.
Cut the membrane into long, thin strips to fit the corners where the shower walls meet.Reinforcing membranes are typically made from tightly-woven fibers.
When sandwiched between layers of liquid waterproofing, they’ll provide an additional layer of water-stopping protection.Leave 2-3 between the membrane and the corners and edges of the shower stall.
A little blank space will make it easier to waterproof these areas separately later on. , Once you've modified the membrane to the appropriate size, cut a large X-shaped slit in each of the spots you marked.
When it comes time to install the fixtures later on, you'll be able to easily fit them into place over the membrane without losing an inch of waterproofing surface area.If you already have a showerhead, faucet and knobs picked out, measure them around the base before you cut the slits so you don't have to make them any bigger than necessary.
Do your cutting with an Xacto or craft knife, and place the membrane on a hard, flat surface that you don't have to worry about scarring up. , Brush the waterproofing over the entire wall using a roller or handheld brush.
Make sure it forms a thick, even coat, with no obvious gaps or bare spots.Paint-on waterproofing products contain liquid rubber, which both acts as an adhesive for the membrane and a forms a bond that’s too tight for moisture to penetrate., Carefully position the precut membrane and stick it to the wall by hand, starting at the top.
Once it’s secure, go over it a few times using the flat side of a trowel to work out any creases or air bubbles.
You may need to use a liberal amount of waterproofing in order to get the membrane sheet to stick.
To help the membrane conform to the corners of the stall, try folding the strips in half widthwise or scoring the backside lightly so that they sit at a 90 degree angle. , Apply the second coat directly over the reinforcing membrane.
By the time you’re finished, the brightly-colored membrane should no longer be visible underneath.Avoid totally covering up the valve and fixture sites.
You’ll need to be able to find these later once it comes time to install the finished surface.
Brush on the followup coat in the opposite direction of the initial coat.
For instance, if you used vertical strokes to apply the first coat, use horizontal strokes for the second one.
This will help create a better seal. , Depending on the size of the shower and the thickness of the adhesive, this may take several hours.
In the meantime, be careful not to touch the materials.
Doing so may wear down the waterproof coating or cause the reinforcing membrane to come loose.
It may be a good idea to begin your project in the afternoon or evening, then wait until the following day to complete it. , Set the sloped tray on top of the subflooring at the base of the shower stall.
If your shower’s floor pan comes in multiple sections, make sure they’re properly aligned and locked before moving on.
Use the circular template included with the installation kit to make a small mark or notch in the subflooring where the drain will be centered.Be sure to arrange the opening for the drain on the same side that the showerhead will be on.
Floor trays are included in most shower installation kits.
They are typically sold pre-sized and ready to go. , Remove the floor tray and find the place where you marked the drain.
Fit an electric drill with a 4” hole saw attachment.
Place the drill head flush against the subflooring and begin drilling, applying constant pressure all the way through.When you’re done, wipe the subflooring with a damp cloth to pick up any sawdust that’s collected nearby. , Brush on the waterproofing the same way you did with the walls.
Aim for a thick coat and even coverage.A handheld brush will be your best bet for applying the waterproofing to the floor. , In addition to the tray itself, you’ll need to lay strips over the cracks where the floor and walls connect.
Afterwards, measure and cut a large hole to fit precisely over the drain opening.
Finish by applying one last coat of waterproofing over the entire floor.If the membrane you’re using isn’t large enough to cover the floor in one piece, you can trim and overlap multiple sections to get just the right size.
For showers with sliding doors, place a strip around the lip of the stall where you enter., Once the materials have had time to set up, they’ll prevent water from seeping into the wall behind and beneath the shower stall.
You’ll then be ready to install eye-catching tile or a vinyl or acrylic liner.
Enjoy a hot shower as a reward for a job well done!Perform at least one one “flood test” when you’re finished to determine whether you’ve waterproofed all parts of the shower stall successfully.
Don’t forget to later set the drain, showerhead and other fixtures in the openings you left for them.
About the Author
Noah Cooper
A seasoned expert in technology and innovation, Noah Cooper combines 2 years of experience with a passion for teaching. Noah's guides are known for their clarity and practical value.
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