No, you cannot use cement board (backer board) as a structural subfloor instead of plywood. Cement board is brittle, lacks load-bearing strength, and will crack under pressure if left unsupported. Instead, cement board is an underlayment designed to be installed on top of a structural plywood or OSB subfloor.
You cannot use cement board as a structural subfloor. It is incredibly brittle and has virtually no shear or structural strength. However, it is an industry-standard underlayment to lay directly over your wood subfloor to provide a flat, waterproof, and stable base for tile.
Oriented strand-board
Also known as OSB, oriented strand board is a popular subflooring material. OSB is similar to plywood subflooring, it has the same installation process, and it offers similar performance. However, OSB can often achieve lower costs than plywood.
For most tile floor installations, 14one-fourth𝟏𝟒-inch cement board is the standard and recommended thickness. It provides a solid bonding surface for the tile without adding too much height to the floor, making it ideal for creating smooth transitions into rooms with carpet or hardwood.
Fixing the Boards to Joists
Apply a bead of polyurethane adhesive to the joists before positioning the boards. Secure each board with two 50mm fibre cement screws per joist, ensuring screws are placed at least 25mm from the tongue and groove edge.
Installing cement board requires a precise approach. The most common mistakes include skipping the thinset mortar beneath the boards, using the wrong screws, failing to tape the joints, and aligning seams directly over the subfloor joints. Ignoring these steps often leads to board flexing and cracked tiles.
Whether cement board is stronger than plywood depends entirely on the type of strength and the application. Plywood is stronger under bending and impacts (making it an excellent structural frame), while cement board is stronger in compression, heat, and moisture resistance (making it ideal for wet areas).
You should never just screw down cement board without mortar. Applying a layer of thinset mortar underneath the board is the most important step for a successful installation, as it prevents the board from flexing, eliminates hollow spots, and stops your future tile or grout from cracking.
Cement board is highly durable and water-resistant, but it is very heavy, brittle, and difficult to cut. It also creates hazardous silica dust when sawed, requires specialized tools for installation, and provides poor thermal insulation compared to foam-based alternatives.
Coca-Cola acts as a powerful surface retarder on freshly poured concrete because of its high sugar content. By slowing down the curing process on the top layer, it allows workers to easily wash away the cement paste with a hose or pressure washer, leaving behind a textured, decorative "exposed aggregate" finish.
The best cheap plywood alternative depends on your project. For budget indoor furniture, use MDF (smooth finish) or Melamine-faced Particle Board (pre-finished). For structural subfloors or sheds, use OSB. For free options, repurpose Pallet Wood.
The cheapest standard subfloor material is Oriented Strand Board (OSB). Costing an average of $𝟐𝟎 to $𝟐𝟓 per 4'x8' sheet, it is typically about half the price of traditional plywood.
The most realistic fake wood floors are high-end Laminate and premium Luxury Vinyl Plank (LVP). Both feature Embossed-in-Register (EIR) technology, which physically presses the texture of the wear layer into the exact grooves and knots of the printed wood grain, making them virtually indistinguishable from real wood.
Use thin-set mortar when installing cement backer board. Thin-set dries slowly, allowing you to fix and readjust backer board sheets as needed. The ingredients in thin-set mortar are cement, fine sand and a water retaining agent. It's used to bond ceramic or porcelain tile and cement backer board.
No vapor barrier should go behind your backer/cement board but you should opt for some type of additional barrier between the tile and cement board such as redguard. Reason for this is that if you had, by chance, some moisture get between the backer board and vapor barrier it would be trapped and cause mold issues.
To attach cement board (backer board) to a wooden subfloor, embed the sheets in a layer of thin-set mortar, then secure them with corrosion-resistant cement board screws spaced every 8 inches. This prevents the board from shifting and eliminates voids, creating a flat, sturdy foundation for tile.
Gypsum board is lightweight, has low shipping costs, and is easier to handle and install. Cement board is larger in size and more difficult to handle and install, especially in larger spaces. Gypsum board can be easily cut with a utility knife.
Termites cannot eat or bore through Hardie Board because its primary ingredients—cement and sand—provide no nutritional value. However, if the siding is installed incorrectly, touches the soil, or covers rotting wooden wall frames, termites can still bypass it to access vulnerable wood behind it.
Typically, the smooth side is used for mastic applications of tile; the rough side for mortar applications.
You should use screws to install cement board. While specialized galvanized roofing nails are occasionally allowed in specific wall applications, screws are vastly preferred. They provide much stronger, reliable holding power and prevent the board from popping up or vibrating loose over time.
Fiber cement siding is one of the most durable, low-maintenance, and long-lasting siding materials available. With a lifespan of 50 to 100 years, it outperforms other siding options in terms of longevity, resistance to damage, and overall value.
Floors: Installation instructions for cement board on floors typically include applying cement-based thin-set between the exterior-grade plywood and cement board. The cement board is then screwed into the plywood while the thin-set is fresh/wet.
Oriented Strand Board (OSB) is the best overall structural alternative to plywood. It delivers comparable strength—especially in shear strength and load-bearing—but is typically 10% to 20% cheaper.
Standard cement board is highly moisture-resistant, but it is not 100% waterproof. It is a porous, cementitious material, meaning it will absorb water if exposed to it constantly. While it won't rot or degrade like wood, water can pass through it to damage the wall framing behind it.
Installing Hardie Board (fiber cement) siding on a 2,000 sq. ft. home typically costs between $14,000 and $30,000+ in 2026, with an average, professional, all-in price of roughly $20,000–$25,000. Costs generally run $7–$15+ per square foot (materials and labor), depending on your location, home complexity, and whether you choose pre-finished ColorPlus technology.