Join my newsletter and get free DIY tips

Bathroom Remodeling the Smart Way-Phase 4 (Cement Board Installation-Pt 1)

Bathroom Remodeling the Smart Way-Phase 4 (Cement Board Installation-Pt 1) post image

 

My last post discussed how to choose the right bathroom building materials in order to avoid a moldy situation down the road. Cement board is a huge part of a smart bathroom renovation because it doesn’t contain any organic matter for mold to use as food.

Today, I’m going to share how we installed cement board in a bathtub recess and what materials are needed to do the project correctly. After reading this post you’ll understand what “good” should look like so that either you can do it yourself or tell a contractor how you want the job done.

Determine Where You Want the Cement Board Installed

The first step in any cement board project is to determine where you want it. In our case, Rob (my brother-in-law whose bathroom we’re working on) wanted the cement panels in the shower surround but preferred to have fiberglass faced purple board serve as the top border.

 

Determine Where You Want Cement Board Installed

It helps to also know the dimensions of a typical cement board panel. They can be bought as either 3 ft by 5 ft or 32 inches by 5 ft. The manufacturers do this because bathtub surrounds have a back wall that is 5 ft long and both adjacent side walls are anywhere from 32 to 36 inches wide. This makes installing cement panels much easier  because it involves less cutting.

 

The Bathtub Back and Side Wall Dimensions Fit the Cement Board Dimensions

 

Ideally you want the cement board to cover any area that will be exposed to water. I don’t know about you but the front wall that contains the showerhead in our bathtub gets saturated with water.  This is a good reason to choose the 36 inch wide cement panel because it will extend out more and add protection against mold forming on any existing drywall that is paper faced.

 

Make Sure the Side Wall Cement Board Panel Extends Beyond the Bathtub Width

 

If you can do it, think about making the ceiling  out of cement board in the bathtub recess, too. Remember, hot air rises and in the bathroom it is especially full of moisture. Even if you do have a fan the ceiling still gets a blast of warm air every time a shower is taken (and even more so if you have teenagers who like taking long showers).

 

Choose the Correct Screws and Joint Tape

When you buy cement board it requires the same installation materials as drywall but with a twist. You’ll need to buy cement board screws that have a special corrosion resistant coating and are much stronger than drywall screws.

 

Cement Board Requires the Use of Alkali Resistant Screws

 

In my last post I discussed how fiberglass drywall joint tape should be used to make wallboard panels one cohesive unit. The same principle applies to cement board. The tape you need to use is alkali-resistant, fiberglass-mesh, and polymer coated. The polymer coating on the tape protects it from the chemicals in the mortar within the cement board itself. This tape can also be used where cement board and drywall meet each other.

 

Cement Board Tape is Alkali Resistant and Can Withstand the Harshness of Cement Board

 

Instead of using drywall joint compound to embed the tape in the cement board you should use thin-set mortar. We utilized the same thin-set that will be used to attach the tiles.

 

Use Thin-Set to Embed Cement Board Tape into Cement Board Joints

 

Having the cement board, alkali-resistant screws & joint tape, and mortar will get you one step closer to installing the tub surround the right way.

 

Let the Installation Begin (With the Back Wall)

In our project, we decided to install the upper back wall panel first. Since the width of the back wall was a little more than 5 feet wide we were able to simply install a full panel without having to trim it. I spaced the screws on the studs about 8-10 inches apart from each other. Attach screws at most 1/2 to 1 inch from the edge of the cement board. Otherwise, the cement will crack.

 

Attach Cement Board to Studs and Space Screws 8 to 10 inches Apart

I prefer to add screws to the top of the cement board then use a level to trace a vertical line indicating the stud position behind the cement panel. Unless you’re Superman or Superwoman it’s hard to see through cement and this step makes me feel better about the screws being directly centered on the studs :)

 

Use a Level to Mark the Stud Positions Behind Cement Board Panels

 

To make the process easier I highly recommend using an impact drill/driver like this Ridgid I’m holding. This is hands down my favorite tool and if you’re doing any DIY projects you need to buy one of these :)

 

Use an Impact Drill:Driver to Attach Cement Board Screws

 

The Americast bathtub we installed had a good 1 inch lip on it, which we attached to the studs using galvanized roofing nails. We also shimmed out the walls with 1/4 inch lath strips so the cement board would sit flush with the lip or slightly beyond it. This will allow the tiles to rest beyond the lip of the tub when we secure them to the cement board later in the project.

I measured the distance from the top of the nail (holding the lip to the stud) to the bottom of the upper cement board panel and subtracted an 1/8 of an inch. This gave me the size of the bottom cement board. It’s important to get this measurement correct because it’s tough to cut 1/2 inch from cement board!!

 

Measure from the Roofing Nail to the Bottom of the Upper Panel

 

Once we obtained the height of the bottom cement board panel I cut it using a special carbide tip knife and the straight edge of my level. Since the cement board is sandwiched between fiberglass mesh tape it needs scored until the mesh is fully cut. I scored one side of the cement panel until the mesh completely severed.

 

Use a Carbide Tip Cutting Knife and Level to Trim Cement Board

Then I bend back the scored portion of the cement panel to expose the other side of the mesh tape. You can either cut the tape with the carbide tip knife or cut it with scissors.

The lower cement board panel was installed just like the upper portion, and rested just above the lip of the tub. One big tip is to make sure the tapered edges of both the lower and upper panels abut each other. This is super important because it provides a recessed space for the joint tape to sit in. Otherwise, you’ll have a hump at the joint and this will cause your tile installation to be uneven & look bad.

 

Make Sure the Tapered Edges of the Cement Board Abut Each Other

 

Our back wall was pretty simple to install. The two side walls are straight forward as well, but I’m going to explain how we attached them to the studs in my next post. There are some details I feel are really important to share and that’s why there will be a Part 2 to this tutorial :)

So I hope this was helpful and if you have any questions please ask away in the comment section below. To get more immediate updates and some funny pictures join me on Facebook and Like Home Repair Tutor by clicking this link.

Thank you so much for visiting, I really appreciate your time and support.

Make it a great day!

Jeff Patterson

 

 

 

 

 

 

 

 

 

 

 

 

Diggin’ this tutorial? Sign up for updates… It’s FREE!


12 comments… add one

  • Eddy April 7, 2013, 4:42 PM

    Thanks for the helpful info. When you hang the cement board, which side is facing out – the smooth or the rough? Does it differ depending on what kind f tiles are being used? Thanks!

    • Jeff Patterson April 8, 2013, 6:02 AM

      Hi Eddy,

      Nice question. The rough side of cement board is the side to hang the tiles on.

      Usually there is a sticker on the board that provides you with directions, though.

      So always read that sticker to be sure of what to do with your specific material.

  • David Henry June 19, 2013, 12:04 AM

    I saw your pictures about doing a tub bath above but did not see anything indicating what type of joint compound to use when joining purple board to cement board. I was told to definitely not use drywall joint compound. I used thin set to join the different pieces of cement board, but since I have a 12″ border of purple board setting above the cement board, I need to know what kind of joint compound that I should use to tape and bed the joints between the purple board and the cement board.

    • Jeff Patterson June 19, 2013, 5:30 AM

      Hi David, we used setting type joint compound that needs to be mixed with water. I prefer this variety over pre-mixed because it dries quicker and becomes rock solid. All the cement board joints were done with thin-set and not joint compound. You can also use thin-set to tape and bed joints between the purple board and cement board. Just make sure the thin-set is a bit thin (pardon the repetitive nature of this discussion) so that when you tile the transition there won’t be a hump that will make your tiles look offset. Hope this helps but let me know if you need more detail.

      • David Henry June 19, 2013, 10:38 AM

        Thanks for the reply about my question as to what type of joint compound should be used when joining purple board to cement board. Remember that I am using a combination of cement board and purple board for the shower walls. The purple board will go above the cement board, for about 12 inches, until it meets the ceiling which is also purple board. You suggested a setting type joint compound and said that thin set, mixed so that it is very thin, could be used. I noticed that when I used thin set on the cement board joints, the joints were pretty rough because of the cement board surface. This didn’t concern me because I new that the 1/4″ adhesive for the tile would basically smooth out the joint. Now, with the recommendation to use thin set (very thin) between the purple board and the cement board joint, I am concerned that it is going to cause the joint to look pretty rough ? I plan to light texture the purple board so I wanted to have a smooth surface, like when using regular dry wall joint compound. Will the thin set, very thin, produce a smooth joint on the purple board side of the joint ?

        Thanks for your help.

        • Jeff Patterson June 19, 2013, 3:22 PM

          If you tile over the thin set joint the rough texture won’t be an issue. But if the joint will be exposed then yes, it’s probably best to use the setting type joint compound instead. Great questions David and always feel free to send a video or pictures to me at jeff@homerepairtutor.com

  • PJ June 17, 2014, 2:54 PM

    We are re-installing shower doors after a bathroom tiling job, and they are a little narrow, as they were before. In the downstairs bath (which someone did before we moved in), they used a painted 2×4 or something close as a shim on one side, overlapping the edge of the tile. They fastened the shower frame to that, and to the tile on the other side, and then used a painted wood trim down that one as well. Is THIS a workable idea? If not, how can we better finish the frame installation on this second bath? We have tiled it flush with the outer edge of the bathtub, and it is a quite unfinished look which wasn’t a concern at the time, since we intended to use the wood trim. Having second thoughts now, and have seen info on the schluters trim. Is it still possible to use this type of finish? (It looks as though it is installed when mortaring in the final edge tiles, but perhaps there are alternatives?) ANY ADVICE is greatly appreciated. Thank you very much.

    • Jeff Patterson June 17, 2014, 3:17 PM

      Hi PJ, thanks for your question. Schluter trim is a great option and can be used when tiling. It is embedded into mortar then tiled over.

      Can you send me a few pics of your situation and we can come up with a solution :)

  • Nate July 4, 2014, 9:08 PM

    I am using concrete board in my shower and am having a hard time getting the screws recessed even with an impact driver, what can I do, I am hesitant to use a hammer on them.
    Thanks

    • Jeff Patterson July 6, 2014, 7:41 AM

      Hi Nate, as long as the screws are only a fraction of an inch off the board you should be okay. But if they’re more than 1/16 of an inch off the panels you’ll need to get them more flush.

      What kind of impact driver are you using?

      • Nate July 8, 2014, 7:41 PM

        A dewalt and no matter what bit I use it has tendency to just spin in the head even at low torgue as if the studs are made of concrete

        • Jeff Patterson July 11, 2014, 7:19 AM

          Hmmm, what size or length screw are you using? I wonder if the screw isn’t long enough to really bite the stud. You’re totally right Nate, the screw shouldn’t be spinning. It should be super tight and suck the board to the stud.

Leave a Comment