This post describes how to replace a tile shower drain grate for a conventional three-piece clamping drain assembly. These clients had a new-ish home in the Mueller neighborhood of Austin, TX. The main bathroom had a designer shower that had some nice elements (a nice size, a convenient bench, classy frameless glass, etc). But it also had a really badly done tile shower floor.

The homebuilder likely left a helper or inexperienced handyman to do the final finish bits including the tiled floor. The pattern wasn’t centered on anything, the cuts around the round drain grate were badly done, the whole perimeter was wonky with irregular gaps, and the grouting was haphazard with lots of splotchy staining all over the honed marble mosaic. It looked terrible.

I’ve previously described how to retile a shower floor to fix things like an improper shower floor slope. This post gives another how-to for retiling shower floors. But it also goes into detail on how to safely replace the tile shower drain grate assembly in the process. This is an easy upgrade that’ll make your custom tile shower classier and easier to maintain.

First, make sure the shower doesn’t leak!

Remember that tile and grout are not waterproof. Shower waterproofing happens underneath the surface tile. Retiling a shower floor will only fix surface problems. It will not make a leaky shower waterproof. In this case, the clients had already been using the second floor shower regularly for a year. If the waterproofing wasn’t done correctly, then it would have started making water stains on the ceiling below within a couple months of first use.

Second, be careful!

Also realize that you need to be VERY careful anytime you crack into a tile shower floor. Remember that the tile sits on top of a light drypack concrete layer that itself covers the actual shower pan liner waterproofing membrane. The liner in traditional shower waterproofing is either a pretty tough fiberglass “pan” or a pretty fragile layer of flexible PVC vinyl with glued seams.

Here’s a diagram that shows what traditional custom tile shower construction looks like:

Removing tile around a drain grate requires hammering and chiseling. So, you need to be VERY careful to not puncture the waterproofing layer beneath the drypack concrete as you do this. If you do, then you’ll need a whole new shower.

Step ONE: get the replacement drain

Whomever tiled this shower floor the first time used the cheapest shower drain assembly possible. That’s why it had a thin piece of metal for the grate that didn’t screw into place. The original installer tried to use caulk to glue the cheap metal grate into place (and to cover up the bad tile cuts). This resulted in an ugly mess that also made it impossible to remove the drain grate to clean out hair etc.

They instead could have used an all metal grate assembly with a thick, durable, removable strainer for literally just $10 more. This is an example of how cutting even seemingly small corners can really screw up the finish on a custom tile shower.

You’ll only need the screw-in top part of the drain assembly. But it’s usually least expensive to just go ahead and get the whole kit. You don’t need a super designer drain grate to make a classy shower. You just want one that’s solid metal with a removable strainer that secures with screws.

Step TWO: demo around the existing drain

This is where you’ll want to start being careful. Remember that you only need to expose the TOP of the existing drain. You want to get just underneath the top screw-in drain grate piece. I like to use a sharp wood chisel to get started, then a small masonry chisel and wide-bladed flathead screwdriver to get a bit into the drypack concrete layer.

You’ll want to cap the drain with a simple drain plug (or even just a rag stuffed into the drain line) during demo. You don’t want tile and concrete bits to get into the shower p-trap.

Again, remember to demo CAREFULLY! You DO NOT want to chisel far down into the drypack concrete layer. This would risk making a hole in the waterproofing liner below. Instead, you just want to remove the surface tile around the drain and only enough of the drypack concrete immediately around the screw-down drain assembly to break it free.

Step THREE: unscrew the old drain grate assembly

This step also requires some care and finesse. You don’t want to pound away heedlessly on a PVC shower drain assembly. Instead, you want to use just a regular hammer and a screwdriver for leverage. Work to unscrew just the top drain grate part (lefty loosey) with gentle taps.

You’ll now want to block the drainpipe with a rag and clean up the PVC plastic screwthreads in the drain base. They’ll be a bit grungy with crystallized uric acid (everyone pees in the shower). You want the threads to be free of all debris for the next step.

Step FOUR: screw in the new drain grate assembly

In an ideal world, this step would be dead easy. But in the real world, this part of replacing a tile shower drain grate is often a pain in the ass for a couple reasons.

First, the drain base threads may be a bit gnarly no matter how well you manage to clean ’em up because the previous installer might have cross threaded them. Or second, even if the threads are in perfect shape they might not exactly match the threading on the replacement drain grate assembly. Different plumbing brands can have slightly different thread specifications.

Pro Tip: Use silicone lubricant or just simple pretroleum jelly to make this step easier, and remember that the drain grate assembly doesn’t have to be threaded completely tight. It just needs to match the new tile height.

And finally, always remember that the original plumber may not have installed the shower drain base completely plumb to begin with. That was the issue on this project. It took some finesse and quite a bit of literal screwing around to get the new drain grate assembly reasonably plumb to drain well with what would be the new surface tile level.

That’s how you replace a tile shower drain grate assembly! Congrats, but realize that the job is only half over. You now have to retile the shower floor.

Step FIVE: make the slope perfect

This shower floor did at least drain completely. But the original shower floor tile had lots of uneven spots especially all around the perimeter. So this was an opportunity to make the shower floor slope perfect with two or three thinset applications.

I like to use highly modified thinset (like this ProLite blend) for leveling shower floors. It’s easy to control the constistency from stiff to creamy. It dries slowly, but once dry it’s easy to scrape and shape smooth.

Here’s the thing. If you’re spending time and money to replace a tile shower drain and completely retile your shower floor, then it’s worth spending an extra day or two to make sure the finish is perfect. You can also just backfill and level the drain area with sand topping mix or simple unmodified thinset if the origional floor slope was perfect.

Step SIX: retile the shower floor

These folks chose a square mosaic tile that almost but not exactly matched the shower floor dimensions. This is where putting arbitrarily sized tile on an arbitrarily sized floor with an arbitrary drain location results in some Sophie’s Choice necessitation. You need to decide what you’re going to use as a visual center.

In this case, the choice was clear. The new replacement drain was the visual center of the shower floor. And mostly centering the square mosaic floor tile on this made the left and right edges almost centered. So you’d think the actual retiling step would be simple? Think again.

Regardless of layout, any mosaic floor tile comes with seam hiding challenges. Mosaic tiles come glued down on 12×12-in plastic mats. And lots of manufacturers don’t have great quality control on the process. See how a lot of the individual tiles on these mosaic mats look wonky?

Pro Tip: Order twice as much mosaic tile as you’ll actually need, and then use the best puzzle piece matches out of the bunch to get the most seamless result.

Or, do it the hard way. In this case the clients chose a mosaic tile that was only available online. So returns weren’t an option. In that case your only cost saving option is to test match the mats together to make ’em as regular as possible (hence the pic above) and then cut out individual irregular tiles to set individually. Either way, you need to do a lot of test fitting and precutting BEFORE install to make sure all the mosaic tile mats fit together perfectly with no visible seams.

Here’s the result of taking some extra pains to make sure that the result is a perfectly sloped shower floor with a mosaic tile pattern that fits the space with no seams between the mats:

Now that looks a lot better than the first job. Preplanning makes perfect, and square shower drain grates are always easier to tile around.

The Result!

This is how you can replace a tile shower drain grate (and the rest of the tile shower floor) without ripping apart the entire shower. Remember that tile and grout aren’t waterproof. This makes it possible to simply tile over top of existing shower floor tile in a conventionally designed shower without doing anything to the underlying shower waterproofing.

Here again was what the original shower floor looked like:

And here is what it looks like now!