Best Cement Boards for the Shower – Comprehensive Guide

Cement Boards for the Shower

Showers are where most of the moisture in your home accumulates. Water from the showerhead cascades down walls into a pool at its base, and such an area must be impermeable to water. To avoid damage caused by long-term exposure to humidity, waterproofing is paramount for any shower installation.

When you’re installing tile in any room of your house, a special substrate or base layer is necessary. The typical substrate for showers is cement board or sheet material that acts as a barrier and shields the underlying structure in the shower from water damage. A liquid membrane can also be used to create this protective layer.

What Cement Board Is

Cement board is a strong and durable mineral-based material, typically measuring 30 inches by 60 inches that serve as the perfect foundation for installing ceramic tile, porcelain tile, or stonework. It is available in two different thicknesses of 1/4 inch and 1/2 inch to suit your needs.

Ceramic and porcelain tiles are particularly sensitive to movement, thus a steady, level base must be provided that is completely rigid. Even the slightest amount of flexing in the building structure can cause cracking in these tiles.


Tile backer board, also known as a cementitious backer unit (CBU), is available from renowned names such as Durock, Denshield, HardieBacker, and Wonderboard. Furthermore, showers and bathtubs require an impervious substrate that will not suffer water damage should the tile or grout crack – allowing water to reach the studs of your shower stall.

When water intrudes behind shower tiles, the consequences can be catastrophic. This infiltration rarely stops independently; causing more moisture to seep through and deteriorate studs while potentially leading to mold growth.

When selecting the right tile backer board for your project, always make sure it is 100% inorganic and at least 1/2 inch thick. Additionally, to ensure optimum protection against water damage, seal the board with a roll-on waterproofing membrane as well. With these tips in mind, you can rest assured that your tile backer boards won’t rot or shrink due to moisture–guaranteeing optimal results!

Best Cement Boards and Applications

When it comes to installing cement boards in your shower, you have an array of recommended options. Typically, this involves combining the tile board with something waterproof such as a liquid membrane, plastic sheeting, or Schluter Kerdi uncoupling membrane; alternatively, you can use pre-coated boards that are already watertight.

Cement Board and Plastic Sheeting

For today’s budget-conscious, popular choice of wall tiling, a moisture barrier composed of 4- or 6-mil plastic is installed directly on the wall studs. Then, the cement board is placed atop the sheeting and held to the studs with screws. To protect against water infiltration even further, an additional roll-on waterproofing membrane can be applied over the tile backer board before laying down tiles with thin set mortar or mastic.


A premium fifteen-pound felt tar paper can be opted for instead of a regular plastic moisture barrier, making it an ideal choice for those looking to maximize their protection against the elements.

Cement Board and a Liquid Membrane

For this application, forego the plastic sheeting altogether and affix the cement board directly to the studs. This eliminates an extra step in achieving a clean finish!

To protect your tiling project from water damage, you need to use a liquid waterproofing membrane like RedGard or Hydro Ban. Roll the membrane onto the cement board and let it dry before installing any tiles on top of it. This is an essential step in ensuring that your tile work will stay safe for years to come!

Cement Board and a Sheet Membrane

This popular application requires a cement board to be placed directly on the studs, with no plastic sheeting in between. Schluter Kerdi’s waterproof membrane is then applied to the cement board using thinset adhesive for extra protection and durability. This trusted brand of uncoupling membrane guarantees optimum security against water damage.

After the thinset has completely dried, you can begin laying down the tile with a fresh layer of thin-set. Kerdi is uniquely designed to be installed directly over drywall in showers due to its ability to create an extra-stable and waterproof barrier when properly used.

Investing in cement board and a sheet membrane might be costly, but it also offers the benefit of separation between your tile flooring from its substrate. This can help reduce or even prevent cracking of both tile and grout!

Membrane-Faced Board Only

Georgia-Pacific’s DensShield is a tile backer board that features water-resistant facings on both sides, completely eliminating the need to install any separate waterproofing membrane. This means you can directly apply thinset mortar onto its surface before tiling and grouting! With such an effective product, your tiles will remain free from moisture for years to come.

Worst Shower Backer Boards and Applications

Traditional tile installation processes have become obsolete due to their use of materials that are no longer suitable for showering purposes. In fact, professionals and tilers alike would never utilize drywall or any other type of unsuitable material, yet inexperienced do-it-yourselfers often opt for these options without proper education on the topic.



Drywall’s paper facing is highly susceptible to even the slightest amount of moisture, and when it makes contact with water, its gypsum core will start crumbling. Its organic nature means that mold can form quickly – making drywall an unsuitable material for shower tiles. Avoid potential damage by ensuring all wet areas are fitted out with suitable backer boards instead.



The reliability of Greenboard as a shower backer board is in dispute. Its water-resistance capabilities are only slightly higher than those of ordinary drywall, with the same gypsum core and paper facing. Nevertheless, its paper covering includes waxes that can repel liquid better compared to typical drywall’s paper lining.

While a few municipalities do deem greenboard as an acceptable shower substrate, many other areas have banned its use. With so many options for non-organic backer boards available on the market today, there is no reason to utilize greenboard – it’s not even easy to find anymore because of superior competing products!



It is a common misconception that plywood, when painted or primed with latex paint, can be effectively used as a backing board for showers and bathtubs. Unfortunately, this simply isn’t the case; plywood cannot function alone as a substrate in wet areas like bathrooms.

While some DIYers may mistakenly assume that plywood can be used in shower wall applications since it’s often utilized as an underlayment for floor tile, this is not the case. Plywood might work fine on floors of other parts of a home where moisture isn’t a problem; however, water-resistant materials should always be employed when constructing showers to ensure long-lasting durability and prevent any potential damage from occurring.