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DIY Bathroom Remodeling Mistakes

Avoid These At All Costs

As Seen On
by Jeff Patterson in DIY Bathroom Remodel
DIY Bathroom Remodeling Mistakes by Homeowners

What are the most common DIY bathroom remodeling mistakes?

You’ll find out in today’s short and sweet tutorial.

Don’t fall victim to these errors!



Mistake #1: Not Shutting Off Water

Always turn off the water to your home before doing any demo.

Too often people only turn off the water at shutoff valves. This can lead to water leaks that ruin drywall and adjacent rooms.

Old shutoff valves frequently don’t work properly and lead to damaged floors.

Do yourself a favor and shutoff the main water supply to your home before doing anything else.

In addition, use SharkBite shutoff valves to quickly replace old valves that don’t work. They’re well worth the $8 or $9 and will keep your project moving along.


Mistake #2:  Not Checking Studs

Studs should be 16″ on-center, even with each other, and plumb.

Why are studs important in bathrooms?

They affect the backer boards which in turn affect your tile work.

Most backer boards, think KERDI-BOARD or cement board, require studs to be 16″ on-center.

Furthermore, bowed or out of plumb studs will cause backer boards to bow out as well. Studs can be either planed down or sistered with new studs to quickly fix these problems.


Mistake #3: Not Inspecting Subfloors 

Subfloors greatly affect the performance of bathtubs and showers.

Wood subfloors should be 3/4″ thick and rest on 16″ on-center joists. Concrete subfloors should be clean, flat, and if possible level underneath shower pans or tubs.

How can you fix bathroom subfloor problems?

Tear out damaged wood subfloors and replace them. It’s work that’ll pay off in the end. Additional joists can be sistered to the old ones to help with leveling the floor.

Self-leveling concrete or wood substrates is also an option. BUT don’t forget to clean the surface and prime it before leveling; these two steps are frequently skipped by homeowners who then wonder why levelers aren’t working properly.


Mistake #4: Not Replacing Rough-In Valves

Please, pretty please, don’t keep your old shower rough-in valve.

Old plumbing will leak. It’s not a matter of ‘if’ it’s a matter of when. Murphy’s Law will make that happen on your birthday or vacation.

Just tear out the old shower rough-in and replace it with a good valve from Delta, Hansgrohe, or Moen.

It’s well worth the time and cost.


Mistake #5: Not Waterproofing Cement Boards

Don’t try to argue this point. All cement backer boards say they’re ‘water resistant’ and NOT waterproof.

Many people want to debate this point. Why would you remodel your bathroom and skimp on the $100 bucket of liquid waterproofing.

Use RedGard, Hydro Ban, or Ardex 8+9. They’re all great products and very affordable.

In addition, use a wet film gauge to ensure you have the right thickness of waterproofing. Many people forget this step and wonder why they have waterproofing failures.


Mistake #6: Not Mixing Thin-Set Properly

Every thin-set mortar bag has specific instructions. Gone are the days of ‘eyeing’ up the thin-set consistency.

These products are made to perform according to the water ratio. If you have too much or too little water the thin-set won’t work properly.

For example, if too little water is used then thin-set can crack and cause bond failures.

We highly recommend using Ardex products because each thin-set can be mixed into small batches, i.e. you don’t need to mix the entire bag.

Which thin-sets are the best for bathroom remodeling?

Ardex X77 is the best for large format tiles in showers. Ardex X5 is our preferred thin-set for small wall tile or bathroom floors.

Schluter’s ALL-SET is our preferred thin-set for Schluter showers. And Laticrete also makes fantastic mortars like 4XLT and Tri-Lite.


Mistake #7: USING Mastic!!!

Never use mastic in wet areas. EVER.

Mastic is organic and that can lead to mold growing behind your tiles.

Needless to say, mold inside showers is not good.

Stick with inorganic thin-set mortars to bond tiles to shower walls or bathroom floors.

Watch our video to get more tips and tricks for your DIY bathroom remodel

What’s Next

Are you attempting a DIY bathroom remodel?

Are you tired of watching YouTube videos?

Check out Bathroom Repair Tutor where we have detailed tutorials and support inside our private Facebook Group.

We cut to the chase super fast and enjoy helping members build amazing bathrooms.

Enroll Today


Jeff Patterson




  1. Randy says:

    I am remodeling my bathroom. I removed an acrylic tub that had floor tile butted up to it. The tile was on 1/2” cement board over plywood. I want to go curbless. Should I still lower the shower floor 3/4” or will using one of the curbless systems butted up to cement board work to have a flush floor.

    1. Hey Randy, we recommend removing the entire floor. Here’s why, you need to have the main floor tied into the curbless shower. Plus, most curbless shower pans like Wedi’Fundo Ligno are 3/4″ thick. It’s very difficult to get the height correct at the transition without tearing up the main floor.

  2. Butch Rive says:

    First bathroom remodel. Removing 1 piece shower/tub & relacing with handicapped assessible walk in shower only. We had to shim studs to be plumb & now my cement board is proud 1/4″ of adjacent butting drywall. How do I fix this issue? to make the transition seamless. Thanks

  3. Harry H. Knowles says:

    Hey Jeff,
    It’s true that many DIY enthusiasts like to skip the waterproofing job. That’s why they must invest more money later on. I totally agree with this point, but why do you prefer RedGuard? I know that many experts like the product.
    What do you think about Kerdi?

    1. Hi Harry, we simply chose RedGard for this project due to cost. But we really like KERDI membrane and foam board products. Frankly, KERDI over drywall (which is what Schluter recommends) would be relatively quick and affordable for most homeowners. And Hydro Ban Board is equally good if not better.

      1. HARRY H. KNOWLES says:

        Hi Jeff,
        I’ve heard some great things about Hydro Ban Board. To be honest, issues arise when inexperienced homeowners try to DIY and the whole installation goes wrong. The most common question that arises is – “What about vapour barriers?” 😀

  4. GG says:

    Jeff – I am doing a new bathroom Reno. Adding stand-up shower with Schulter Kerdi pan. Schulter says the membrane is fine with their thin sets. Would it make sense to coat the shower pan + surround for a foot with Ardex 8+9? Thank you.

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