How to Install Cement Board: A Step-By-Step Guide

Install Cement Board

Do you need to install a cement board for a project? This step-by-step guide will show you how to do it correctly, so your finished project looks great. Cement board is an important part of many home improvements projects, such as tile installation or shower remodeling. It’s important to install it correctly so that it lasts for years and provides a solid surface for your project. Follow these steps and you’ll be able to install cement boards like a pro!

Cement board is the new industry standard for installing ceramic, porcelain, and stone tiles with thinset mortar adhesive. Notable trade names such as Durock, Hardiebacker, and WonderBoard have developed cement boards that are increasingly used instead of plywood or drywall backer materials when it comes to wall-tile applications found in wet spaces like showers or tub surrounds.

A cement board is an exemplary foundation for ceramic tile, as it has no organic materials that can lead to mold growth, rotting, shrinkage, or decomposition when moisture levels are high. With the use of cement board beneath your tiles, you can rest assured knowing that you’ll be displaying one of the most resilient surfaces available.

The Surface Below the Cement Board

Whether you’re installing cement boards on floors or walls, the surface below it will vary accordingly.

  • Flooring: When it comes to ceramic tile flooring, a 5/8-inch exterior grade plywood or OSB is typically used as the foundation. If you’re looking to install new tiles on an existing floor, then cement board can be laid right over the finished surface – but only if there are no issues with extra thickness and the condition of the current floor is sound. What’s more? You don’t even need a backer board when installing onto concrete – just make sure that it’s flat and free from major cracks before laying down your ceramic tiles!


  • Walls: When dealing with particularly wet areas, such as shower stalls and bathtub surrounds, cement boards should always be directly affixed to the wall studs; a moisture membrane can also be applied between them. However, it is essential not to place the cement board on top of drywall or greenboard in these highly saturated spaces. Instead, existing material should first be removed before fastening any boards onto the underlying studs and possibly membranes if needed. Seams must also be properly waterproofed for some products as per the manufacturer’s instructions so skip this precautionary step at your own risk!


Stocking up on DIY supplies can never be easier – cement boards are available in two convenient sizes, 3 x 5 and 4 x 8 feet, but the size you choose should depend largely on weight.

A standard 3×5 foot panel of 1/4 inch thickness weighs a mere 30 pounds while a thicker 1/2 inch sheet will set you back 36-44lbs.

For amateur DIYers who are more comfortable with lighter loads, it’s best to opt for the smaller panels which won’t leave your hands trembling after carrying them home!

To select the most suitable sheet thickness for your project, consider the purpose it will serve.

  • Floors: It is recommended to use a 1/4-inch minimum thickness, but thicker panels are even better.
  • Walls: To ensure that your tile is held in place and has a strong foundation, opt for a 1/2-inch or 5/8-inch thick cement board rather than the thinner 1/4-inch choice. This extra thickness will better support the tiles as they span between studs.
  • Countertops: For a perfect countertop, choose from panels in sizes of either 1/4 inch, 1/2 inch, or 5/8 inches.

Before You Begin

To ensure that your project is successful, it is vital to understand how to cut cement boards into the sizes you need before beginning. Not doing so could result in costly mistakes, making this crucial step worth taking!

To cut cement boards, you can use a utility knife and T-square. Carefully score the sheet deeply with two to three passes of the knife, keeping your cutting line straight as you go; snap off the excess bit once done creating an even break. If needed, make sure to also clip away any fiberglass mesh on its backside for a complete finish!

For a precise and clean round or curved cut, you’ll need to arm yourself with either a jigsaw featuring a carbide blade or a drill fitted with an appropriate hole saw bit.

What You’ll Need

Equipment / Tools

  • Bucket
  • 1/4-inch notched trowel
  • Drill-driver
  • T-square
  • Utility knife
  • 4- or 6-inch drywall knife


  • Cement board
  • sheets
  • Thinset mortar
  • Cement board screws
  • Self-adhesive cement board mesh joint tape

Instructions Installing Cement Board on Floors

Step 1 – Plan the Installation

Formulate a plan for the arrangement of cement board sheets according to your desired coverage area and sheet size. To increase floor rigidity, ensure that the joints between each cement board sheet are offset by 8 inches from those in the plywood (or other) subflooring. When necessary, begin with a partial sheet so you can create this required off-set pattern.

Step 2 – Mix and Apply the Mortar

Mix and Apply the Mortar

Mix a moderate amount of thin-set mortar in accordance with the maker’s instructions by stirring together dry powder and water inside a bucket. Spread an even layer of mortar over the subfloor using a 1/4-inch notched trowel, forming a mound big enough to cover just one sheet of cement board.

Step 3 – Install the First Sheet

Begin by laying the first sheet onto the mortar bed with its rough or embossed side facing up, depending on your needs. Make sure to leave a 1/4-inch gap between all edges of this sheet and any surrounding walls before securing it in place with cement board screws. To ensure optimal performance, these should be spaced 8 inches apart and inserted flush (or slightly recessed) into the surface using a drill driver.

“Cement board screws and alkali-resistant cement board joint tape are essential for successful installation; conversely, standard screws or drywall joint tape could not endure the proximity of the cement board since they would corrode or deteriorate quickly.”

Step 4 – Add Subsequent Sheets

Add Subsequent Sheets

Utilizing the same strategies, position and secure all other sheets in the first row with a 1/4 inch space among them, and a 1/4 inch gap to each wall. Make sure that you spread your mortar evenly to ensure an even application of adhesive.

Step 5 – Install the Remaining Sheets

Install the Remaining Sheets

Continue installing the sheets until the entire area is covered. For a seamless transition, be mindful to stagger or offset any joints between the cement board and underlying plywood with at least 1/4″ spacing in-between. Furthermore, only mix up freshly prepared mortar as needed; doing so will prevent it from drying before you completely use it all up!

Step 6 – Tape and Mud the Joints

Tape and Mud the Joints

To ensure a secure bond, apply cement board joint tape with its self-adhesive backing to all the connections between sheets. Afterward, mix some thin-set mortar and spread an even layer over the taped joints using a drywall knife as you would when mudding up drywall seams. Tool the mortar with your knife to make sure that it covers each of the taped areas for flat and smooth joins. Allow ample time for drying following manufacturer instructions before moving forward with additional steps in your project.

Installing Cement Board on Walls and Countertops

Installing cement boards on countertops follows the same steps as you would use for floors. However, an extra strip of cement board is needed along the outer edge of your countertop to create a substantial enough surface area to secure bull-nose or any other kinds of edging tiles. When installing this material onto walls, there’s no need for mortar since it will be attached directly to wall studs with screws.

For the best advice on how to protect your wall studs from moisture, contact the cement board manufacturer. They can offer guidance on what type of water-resistant membrane or thick plastic sheeting may be most effective for your project.