If you’re contemplating the construction of a new home or a renovation or addition to your existing one, one of the issues you may face is where to use cement board vs drywall in your project. The two building materials are somewhat similar but in most cases, will have different uses.
Read on for a detailed look at cement board vs drywall, along with some guidance as to when and where you should consider using each as part of a home construction or improvement project.
Comparing Cement Board vs Drywall
First, let’s take a quick minute to explore the specifics of cement board and drywall before we get into when and where to use cement board vs drywall in DIY projects.
Cement board is also commonly referred to as backer board, a nod to one of its primary uses as a backing material over which tile and countertop materials are installed in bathrooms and kitchens.
Comprising a mix of plant fibers, cement slurry, and fiberglass, cement board can be installed as a tile or countertop underlayment using thin-set adhesive or mortar and grout. It can also be attached to wall framing with nails or screws as a prelude to tile installation.
Types of Cement Board
There are four types of cement board — fiber, wood wool, cement-bonded particle board, and wood strand cement board. Generally, all four types can be used for interior underlayment — and for exterior wall construction, if wanted — with some types having special uses, such as roofing or furniture construction.
Sizes of Cement Board
Cement board is available in both 3×5-foot and 4×8-foot sheets. It can be found in ¼-inch and ½-inch thicknesses and is also available in ⅝-inch sheets from some sources.
A basic 3×5-foot panel of ½-inch cement board is available from home centers and building supply stores for around $14. A 4×8-foot panel of ½-inch cement board should cost somewhere around $25.
In terms of cement board vs drywall, cement board is extremely hard and dense, meaning that it is very resistant to impact and has significant weight-bearing capabilities.
That resistance to impact makes cement board a great choice for exterior applications, and its weight-bearing capabilities mean it does well as an underlayment in heavily-trafficked areas like bathrooms. The weight-bearing capacity of cement board also explains why it is a good choice for supporting wall tiles.
Going further, the density of cement board makes it very resistant to moisture, another reason why it’s a good choice for use in bathrooms and kitchens.
Drywall’s primary component is calcium sulfate dihydrate, more commonly known as gypsum. For a finished sheet of drywall sheathed in thick paper, dehydrated gypsum is mixed with various additives, like starch, to provide its strength.
Types of Drywall
There are a number of different types of drywall, starting with the 4×8-foot, ½-inch thick panel most widely used. There is also “green drywall,” a wax-coated product that provides enhanced moisture, mold, and mildew resistance. So-called “purple drywall” offers even more moisture protection.
Beyond that, there’s Type C and Type X drywall, both of which are sheathed in fiberglass for enhanced fire protection. You can also find “soundboard” drywall if you’re interested in soundproofing a particular space.
Finally, there is VOC-absorbing drywall. VOC stands for volatile organic compounds — air pollutants — which are soaked up by this special type of drywall.
Sizes of Drywall
Drywall most often comes in ½-inch thick 4×8-foot sheets, although it is available in 4×10-foot and 4×12-foot sizes. Drywall is available in a number of thicknesses — ¼-inch, ⅜-inch, ½-inch, and ⅝-inch.
In terms of usage, ¼-inch drywall is employed most often to cover an existing layer of wall as an easy way to hide blemishes. Three-eighths-inch drywall is most often used as a drywall patching material.
Half-inch drywall is the standard for wall construction, with ⅝-inch drywall sometimes used for wall construction for its soundproofing and fire protection qualities. Five-eighths-inch drywall is the current standard for commercial construction.
In general, drywall is less expensive than cement board, starting out at around $12 for a standard 4×8 sheet and moving into the $20-plus range for drywall with special properties like enhanced mold resistance.
Drywall is classified as an extremely durable material, and it can last indefinitely in residential applications as long as it is kept free from moisture infiltration and is not damaged accidentally with pieces broken away from the rest of the wall.
Pros and Cons of Cement Board vs Drywall
As you might imagine with cement board vs drywall, cement board is routinely more durable than drywall, given that it is constructed of more durable materials. But cement board is more expensive than drywall, and it has some fairly specific limitations on its use.
As already noted with regard to cement board vs drywall, cement board largely is limited to use as a base or underlayment for tile installed in kitchens and bathrooms. It’s possible to use some types of drywall as underlayment, but it’s routinely best to use cement board for those applications.
Conversely, while cement board can be used as a wall surface, it is heavier than drywall and thus more difficult to work with in terms of the large panels typically used for wall construction. Additionally, cement board is far more difficult to finish with paint or any other covering than is the case with drywall.
Other important differences between drywall and cement board include the fact that drywall is much easier to work with. Cutting drywall, for instance, can be done with a utility knife, but cutting cement board will require masonry cutting tools.
Also, drywall can be installed with screws specifically designed for it, while cement board requires specific decking screws, or roofing nails, for proper installation.
Where to Use Cement Board vs Drywall
As has been mentioned throughout this post, cement board is the proper choice for establishing a surface onto which floor, wall or countertop tiles, or other materials can be installed in bathrooms and kitchens.
It’s possible to use drywall for those applications in some instances, but any initial savings in material costs stands a good chance of being lost if moisture infiltrates drywall used where cement board would have been the better choice.
Conversely, though, as already mentioned in this post, there are places where cement board could be a good replacement for drywall. In places where moisture and humidity might be a problem, such as a laundry room, it might make sense to use cement board rather than drywall as a wall surface.
Cement Board vs Drywall Frequently Asked Questions
While you now have a basic understanding of cement board vs drywall in terms of DIY projects, you almost certainly have some additional questions about the two materials. Read on for answers to some frequently asked questions regarding cement board vs drywall.
What level of humidity dictates the use of cement board over drywall?
Ideally, the humidity level of your home should range consistently between 40% and 60%. Of course, there are some areas — bathrooms, most notably — where the presence of moisture will send humidity much higher, at least on occasion.
That’s why cement board is used in bathrooms as tile underlayment and in kitchens as counter underlayment. However, if there are other high-humidity areas in your home — a laundry room, perhaps, where clothes are hung to dry — cement board might be a good choice as a wall material.
If you’d like to have a clearer picture of humidity levels in your home, hygrometers that measure moisture levels are available from Amazon.
Are there circumstances where cement board and drywall can be used interchangeably?
Broadly speaking, there are instances in which the question of cement board vs drywall can be answered with either material. For instance, both drywall and cement board can be used as underlayment for roof and wall installations.
Both materials also can be used as underlayment for countertops, and drywall treated to be moisture-resistant can, like cement board, be used as underlayment for a bathroom floor.
But, just to be safe, be sure to consult with your home center or building supply professional before deciding between cement board vs drywall for your particular DIY project.
Can cement board be installed over drywall?
There is some debate among building professionals as to whether cement board can or should be installed over drywall. But for the average DIYer, there’s just one answer to this question: Don’t do it.
When you apply cement board over drywall, the drywall can’t breathe. As a result, even a small amount of humidity or water infiltration into the drywall can cause it to mold or rot behind the cement board.
Can drywall be installed over existing cement board?
There is little advice available on whether drywall can be installed over cement board, an indication that it is seldom tried, if at all. That’s a clear indication that it’s not something that a DIYer should attempt.
In this light, it’s good to remember that cement board is primarily intended as a backing material for tile installation on bathroom walls and floors. But if you are dealing with a cement board wall installation that has become damaged, try applying a skim coat of plaster over it to hide the problematic defects.
Wrapping up Cement Board vs Drywall
So now that you’ve learned about cement board vs drywall and have an idea of where each one could or should fit into your DIY plans, you should explore DIY Painting Tips for even more information.
To find out more about drywall, check out our Drywall Repair page where you’ll find links to all kinds of drywall-related posts and guides.