Well, it turns out that you can actually swap out drywall for cement board – but that doesn’t mean you should ditch your standard gypsum drywall panels altogether.
Here’s what you need to know about drywall vs cement board and when it’s appropriate to use each.
What’s The Difference Between Cement Board and Drywall?
Drywall is made of gypsum – a naturally occurring mineral that is non-combustible, making it great to use in homes. It has a gypsum center and paperboard outsides.
Cement board is also somewhat mineral-based. It usually has a cement mortar center and a fiberglass mesh cloth shell.
There are a few different types of drywall.
Regular drywall is gray or white and is the standard for most interior rooms. Green and purple drywall have been treated with a water and mold-resistant coating and used for bathrooms, kitchens, and other areas that deal with high moisture.
The last type of drywall is type-X fire-rated drywall. While gypsum is already fire-proof to some point, this drywall has additives that make it withstand high heat for more extended periods.
The most common thicknesses for drywall are 1/2 inch for walls and ⅝ inch for ceilings. Drywall comes in 4 x 8’ and 4 x 12’ sheets.
Now, let’s talk about cement board.
It’s not common to see cement boards installed on the wall. Instead, most people use it for tiling.
This is because cement board doesn’t warp or break down when it gets wet. Therefore it provides a stable foundation for tiles to sit.
Cement board is much more waterproof than even green or purple board. This is why many contractors use it for shower ceilings and behind showers.
Greenboard that is ½ inch thick in a 4 x 8’ sheet is approximately $12 or $0.38 per square foot.
Finally, purple drywall of ½ inch thickness in a 4 x 8’ sheet costs about $17 or $0.53 per square foot.
Here’s a side by side look, all for ½ inch thick cost per square foot:
Cement Board: $0.67
Purple Drywall: $0.53
Green Drywall: $0.38
Standard Drywall: $0.25
So, if you’re drywalling a huge space, it’s easy to see that cement board will skyrocket your costs. This is why it’s generally best to use cement board under tiles, in showers, and in other places that deal with extreme moisture.
Is Cement Board Better Than Drywall?
Cement board is much more waterproof than all types of drywall. Cement board also doesn’t warp or break down. This is why it’s best to use under tiles and in showers.
However, just because cement board is more waterproof and less likely to warp, it doesn’t mean it’s better. Drywall is still a perfectly suitable material to use on the wall, is less expensive, comes in larger sheets, and is easier to install.
Can You Use Cement Board Instead Of Drywall?
While you can use cement board instead of drywall, it’s not always practical. For starters, cement board is 2-3 times the cost of drywall.
It’s also harder to find cement boards in the larger 4 x 8’ sheets.
Cement board does have its place, though, and is very useful for high moisture rooms.
Can You Install Cement Board Over Drywall?
There’s a debate as to whether you can install cement board over drywall. If you want to err on the side of caution, don’t do it.
The reason is, when you apply cement board over the top of drywall, the drywall can’t breathe. Therefore, if there’s high humidity in the room or moisture develops, the drywall will absorb the moisture and mold or rot.