How to Waterproof a Shower Before Tiling

It may be tedious, kind of stinky, and not seem like you’re doing much, but learning how to waterproof a shower before tiling could save a lot of issues down the line.

A few months ago we had a whirlwind few weeks where we weren’t quite moved into our new house but had to do a few updates to our old soon-to-be rental house, including replacing the old tub and tiling a new shower surround.

The only problem was, that’s a one-bedroom house so we didn’t have a place to shower while the tub was gone and the new house was in the process of being re-plumbed so we had access to a shower there but not any toilets.

So, we would live like normal at home during the day without a shower but access to a toilet, then come over to the new house at night to shower. In the grand scheme of things it wasn’t so bad, but try telling that to a heavily pregnant woman (read: me) who just wants one fully functioning bathroom as she’s nesting.

Anyway, we had the old tub and surround removed and replaced with just a tub, then had the plumbers leave the walls exposed at the studs so we’d be able to pick up the rest (and save the $2,000 we were quoted for tile work).

Start with cement board

I did a ton of research on how to waterproof a shower before tiling because I was so nervous about making a mistake and a leak or moisture causing issues behind the walls where we couldn’t see it worsening, especially in a rental house.

We started by cutting and installing cement backer board around the entire surround, ensuring the pieces were screwed into the studs with cement board screws and that they were flush with the existing walls (you may need to use shims between the backer board and the studs if it’s not flush).

We used hole saws for the cuts around the plumbing and honestly shocked ourselves with how accurate they were, that never happens.

In this step it’s a good idea to tape off your tub and lay some plastic inside because mortar and the the waterproofing membrane can get pretty messy.

Tape the seams and start mortaring

Use self-adhesive backer board tape over all the seams – where the boards meet, along the edges of the wall, around any windows, and along inner corners.

Take mortar and a taping knife and start running them along all those seams, ensuring the mortar is as smooth as possible while still covering the gaps. You don’t want to be able to see any gaps or holes at all.

Also add some mortar over every screw hole because there’s a chance those will let moisture seep in as well if they’re not covered.

Start waterproofing

In obsessively Googling “how to waterproof a shower before tile” it kept coming back to recommendations for a product called Redgard. It’s a bright red, kind of fumey thick goop that rolls on like paint but is the consistency of something like meringue.

I wore a mask while using it out of precaution especially being pregnant, but it’s really easy to use. I just loaded it into a paint tray and used a regular paint roller to apply it all over the cement board area. It goes on pink and dries red so you can tell when it’s fully dry, but I ended up doing two coats just to be safe.

Let dry and you’re ready to tile

Once the Redgard was fully dry (I waited a full day but check your specific product’s recommendations), I was ready to tile. It’s as simple as adding mortar right over the newly red walls and tiling like normal. We did a simple, classic subway tile with dark grout and are so happy with how it turned out (and a little jealous our renters got to live with the nice new tiling while we lived there with a gross old tub). And now that you know how to waterproof a shower before tiling, you’re ready to tackle that bathroom remodel.

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