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10 Reasons Why Your DIY Shower Makeover Will Fail

Read This Before Attempting Your Bathroom Remodel

As Seen On
by Jeff Patterson in DIY Bathroom Remodel
10 Reasons DIY Showers Fail

Why do DIY showers fail?

There are lots of reasons. But we’ll show you 10 that most DIYers make.

And you’ll see how to avoid these shower mistakes to give yourself the best chance of getting professional results.

Let’s dive in!


Reason #1: Structurally Unstable Joists

Joists are the foundation of most bathrooms. If joists are structurally unstable the rest of your bathroom remodel is compromised.

What makes a joist fail?

Most of the time it’s either a notch or bored hole.

The International Residential Code sets limits on how big a notch or hole can be in joists. Furthermore, code mandates notches and holes be located in certain locations within the joist.

If you’re not familiar with these codes get the IRC book for One- and Two- Family Dwellings.

Ultimately, the first thing you should do is inspect the notches and bored holes to see if they meet IRC code.

Then beef up the joists by either sistering new ones to the framing or replacing old joists altogether.

Finally, most shower systems require joists to be 16″ on-center; double-check the manufacturer recommendations.


Reason #2: Improper Subfloor Thickness

Thin subfloors can deflect and cause showers to leak. In addition, improper subfloors can also cause cracked tile and grout.

The minimum recommended subfloor thickness for most shower systems is either 5/8″ or 3/4″ plywood or OSB.

Don’t let anyone tell you OSB is bad. The American Plywood Association has a great explanation about OSB and why it’s used for building homes. OSB is made from waterproof heat-cured adhesives and rectangularly shaped wood strands that are arranged in cross-oriented layers.

Basically OSB is super strong and can withstand wind and seismic conditions. So OSB in the bathroom…not a problem.


Reason #3: Wrong Thin-Set Consistency

Most prefab shower trays are bonded to wood subfloors with thin-set.

DIYers, and even some contractors, make the mistake of not measuring water when mixing thin-set.

This makes the thin-set bond strength to be bad or creates voids between prefab shower trays and the subfloor.

Bottom line, measure water when using thin-set mortar like ALL-SET.

Also, use the trowel size recommended by the shower tray manufacturer.

For example, Schluter requires the use of 1/4″ x 3/8″ square or u-notched trowel.


Reason #4: Bad Drain Connections

Shower drains are notorious for leaking.

But their installation doesn’t have to be complicated.

The first step for most shower drains is to cut the drain pipe square and flush with the subfloor.

This can be done by holding a carpenter square against the pipe and cutting it with an oscillating multitool. Then follow the drain installation instructions.

Schluter showers have the best drain in our opinion. The reason why is simple: installation is easier and more permanent than other drains.

Some drains, like the one for Wedi’s curbless shower, rely on the rubber caulking gasket for a watertight seal. But Schluter’s KERDID-DRAIN is permanently glued to pipes and a much better installation method.


Reason #5: Improper Stud Spacing

Every single 1/2″ backer board requires stud framing to be 16″ on-center.

Cement board, Hydro Ban Board, KERDI-BOARD, Wedi…they all specify 16″ on-center studs.

Studs spaced more than 16″ o.c. allow 1/2″ backer board to deflect too much.

Deflection causes tiles to crack and creates an opportunity for the shower tray/backer board connections to leak.

Also, studs should be even with each other and plumb so that tile setting is easier.

Do yourself a solid, check all the studs before waterproofing shower walls.


Reason #6: Wrong Shower Valve Depth

Every shower valve should be installed over solid blocking.

Here’s the problem, if the shower valve is set to the wrong depth, the trim kit won’t work properly.

For example, shower valves set too far outside the stud bay might have a gap between the tiled wall and escutcheon.

This isn’t good.

Fortunately, most shower valve manufacturers like Delta and Hansgrohe specify how deep to place the valve inside the wall.

For instance, a scrap piece of 2×6 can be nailed inside the stud wall and the Delta valve mounted on top. If the stud wall is actually 2″ x 4″, like in older homes, an additional piece of plywood can be used to set the valve at the right depth.

Long story short, read the shower valve instructions carefully, and set it to the correct depth.


If you’re building a shower watch the LIVE YouTube Workshop we did.

It’s called 10 Reasons Why Your DIY Shower Makeover Will Fail

You’ll see all the tips mentioned above plus several more – it’s well worth the time and you’ll avoid a lot of mistakes


What’s Next

Doing a bathroom remodel is tough.

If you’re feeling stuck and want help, check out Bathroom Repair Tutor’s Video Library.

The video lessons are step by step and walk you from start to finish through bathroom renovations.

Let us know if you have any questions and we’ll do our best help.

Hope you have an awesome day!


Jeff Patterson



  1. Michael Varriale says:



    I am planning a shower replacement. I am a DIY weekend warrior. I’ve done tile before. So far so good. Never done a shower… Should be fun.

    My current shower looks like a phone booth with walls on three sides and a glass door. My intent is to remove the ‘free standing’ wall and replace the existing shower with a two sided glass enclosure. ( Two walls of tile, one glass wall, one glass door ). Should look nice and open the room.

    So here is my question…. Current shower has a center drain with a 4 inch curb into the shower. I want to switch to a linear drain. Your video explains why it needs to be on the door side ( you explained lip, slope and trip issue… What about the other glass side? What would you suggest to handle the slope?

  2. Colin Brown says:

    O.K….I live in California. My brother in law is helping me remodel my bathroom. We’re replacing the shower with a curbless shower and he says all we need is purple board and redguard for the shower walls ( cement foundation ). That cement board would not be required for tiling, is that true?

    1. Hey Colin, that’s not a great idea because RedGard isn’t approved over drywall. I’ve called Custom Building Products and asked them about this and they said not to do it. So I recommend using cement board for the walls and using at least two coats of RedGard, same with the floor if you’re using just concrete and not a liner.

  3. George says:

    This post has made it easy for troubleshooting shower failures. Thanks.

    1. Thanks George, happy this helped out

  4. Michael Driscoll says:

    Hey Jeff:

    Thanks for your HRT.
    I’m in the middle of a full bathroom renovation and I have a question.
    Since my wood subfloor is uneven and I will be leveling. I plan on using Ditre.
    What thinset should I use. Because my final floor will be a combination of both wood and cementacus material.
    Thanks for any input.
    Mike D.

    1. Hey Michael, great question. Try to use Schluter ALL-SET. Although it’s a modified thin-set, Schluter approves the use of ALL-SET over plywood. Plus, you can use it to set the tile over the DITRA. If you can’t find ALL-SET, try using another modified thin-set like Ardex X5. Hopefully these tips help with your full bathroom renovation!!

  5. GG says:

    Hello Jeff – I am doing a new bathroom with Schluter Kerdi Pan + Kerdi membrane on cement board for surround. For enhanced water proofing, what are your thoughts about using ardex 8+9 on shower pan + foot around the surround. Have you used this system before? Thank you.

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