Water can find the smallest space in a bathtub or shower space and create a big stinky problem over time.
Unfortunately, I’ve been the recipient of many aspirins because of water leaks not only in our own houses but in multiple rental homes.
But it doesn’t have to be this way, especially if you’re thinking of remodeling your bathroom.
If you’ve been reading my blog you know that I’ve been helping my brother-in-law install a new bathroom. He decided to completely remove the existing blue bathtub (this blue must have been a popular color in 1975!) in favor of a tiled space.
The last post we put up about this project dealt with how we installed cement board.
Today I’m going to share how I made the cement panels completely waterproof using RedGard (1 gallon costs $50).
I’ve discussed RedGard before because it prevents water from seeping into walls & serves as a crack prevention membrane for the tiles.
I’m sharing this experience so that either you can waterproof your cement board or instruct your contractor to do what I did. Like I’ve said before, even if you don’t do this type of work it’s always a good idea to familiarize yourself with the process so that you know a good job is being performed on your behalf.
Being your own advocate is a smart thing in any endeavor and especially so in home remodeling.
I know this post will guide your bathroom renovation project in the right direction. If at any point you have a question or tip of your own, please type it in the comment section below. I love hearing about your projects!
Add Cement Board Tape to All Seams
The last few posts about this bathroom remodeling project discussed hanging cement boards to the bathtub wood studs. Cement board is the cheapest backer board for showers.
I also like KERDI-BOARD because it’s faster to install. Whether you’re doing a small bathroom remodel or a large project, the tips in this tutorial are great.
Adding self-adhesive alkali-resistant fiberglass tape to all the cement board seams is a really important step. This tape needs to be applied to every area where the cement board panels butt against each other or other sections of drywall/plaster.
I added tape to all the seams and then used a thin layer of thin-set to embed it onto the cement board.
The thin-set was the same kind used to adhere the tiles to the cement board panels and the consistency should allow it to just barely hang off a margin trowel or putty knife.
Smooth out the thin-set before it dries. Use a damp spong to feather the thin-set because any ridges or bumps will cause the tile to lay unevenly. Use a level to check and fix any peaks or valleys.
I also applied a thin layer of thin-set to all the screw heads in the cement board. By the time you’re done with doing all this, your bathtub space will look like the following picture.
The thin-set will need to dry for about a day. Once it’s rock solid take a level and make sure all areas where the tile will be placed on the cement board don’t have any peaks or valleys.
This is especially important if you’re installing subway tile showers. The smaller the tile the flatter the backer board has to be. Otherwise, the tile will be wonky and look super unprofessional.
Prep Work for RedGard
The prep work for RedGard is straightforward. Since it does have a thick texture, RedGard should be applied only to the areas where there will be tile.
Also, don’t get RedGard on the tub. I used blue tape along the edge of the tub where it met up with a cement board.
Then, I placed a piece of cardboard on top of the tub to further protect it from any RedGard drips.
The last step for RedGard prep is to dampen the area where it will be applied. I used a bucket of water and a sponge. Take special care to get the corners of the cement board damp as this is the location where you want the RedGard to really adhere.
Now the RedGard is ready to be applied. It’s actually a pretty fun process, but make sure to wear a respirator because it’s stinky.
RedGard Creates a Waterproof and Crack Resistant Membrane
Applying RedGard to any surface is super easy. If you can paint a wall you can use RedGard. And for this shower, we only needed one gallon.
There are two ways to get RedGard on cement board panels:
- Roll it on the wall with a 3/4 inch nap roller
- Trowel it on the wall
Use a good roller that won’t shed into the RedGard. I really like Purdy rollers and used a 3/4″ nap roller for this project.
The first application was put on vertically.
Use a paintbrush for areas that are unreachable with the roller. I paid close attention to applying a good coat of RedGard to all the corners and spaces adjacent to the tub since these are the areas that water likes to penetrate the most.
How long does it take for RedGard to dry?
I let this first coat of RedGard dry until the panels appear red in color. This took about 1 to 1.5 hours.
Drying time depends mostly on temperature & humidity.
And the surface will appear pink until the RedGard has completely dried.
When the RedGard appeared red and wasn’t tacky I applied a second coat horizontal to the first.
Again, as you roll it on the walls check to make sure there are no bumps or small lint boogers in the coating.
The end result should be a bathtub surround that is red in color.
The bathtub walls are now completely waterproof and the RedGard also serves as a crack isolation membrane. This means RedGard will expand and contract ever so slightly to prevent cracks from forming in the shower tile.
Keep in mind, that the thickness of RedGard should factor into how far to set a shower valve like the Delta R10000.
There are many ways to waterproof a shower, so pick the one that works best for you.
If you’re doing a bathroom remodel and need help, join one of Home Repair Tutor’s online courses and make your project easier.
Let me know if you have any questions and I’ll do my best to help.