28 Jul What is Cement Board and Where Can You Use It in 2025
Table of Contents
You may wonder what is cement board. This sturdy panel combines Portland cement with a glass-fiber mesh. Standard sheets measure 3 feet by 5 feet and range from 1/4 inch to 1/2 inch thick. You use cement board as a strong, moisture-resistant backing for tile. Unlike drywall or wood, cement board stands up to water and impact. Many builders choose it as a smart option among modern building materials.
Key Takeaways
Cement board is a tough panel. It does not get damaged by water. It is made from cement and glass-fiber mesh. It works well in wet places and places that get hit a lot.
It does not let water in. It does not catch fire easily. It does not let mold grow. It lasts longer than drywall or plywood. This makes it great for bathrooms, kitchens, floors, and outside walls.
There are different kinds of cement board. Each kind is good for a different job. Fiber cement board is good for siding. Cement backer board is good under tiles.
You should always seal the joints. Use waterproof layers in very wet places like showers. This keeps your home safe from water damage and mold.
Cut, fasten, and seal cement board the right way. This gives a strong and steady base for tiles and other finishes.
What is Cement Board
Composition and Structure
If you ask what is cement board, you see a panel made from Portland cement, sand, and glass-fiber mesh. These materials get pressed together to make a hard, solid sheet. Most sheets are 3 feet by 5 feet in size. You can pick a thickness from 1/4 inch to 1/2 inch for your project.
The glass-fiber mesh makes the board stronger. Portland cement holds all the parts together. Some boards have cellulose fibers or other things added. These extras help stop the board from cracking or breaking. The finished board is water-resistant and works well where there is a lot of moisture.
Tip: Always read the label to check thickness and what is inside before you buy cement board. Brands may use different mixes.
Key Properties
Cement board is known for being tough and strong. You can use it in wet places like bathrooms, kitchens, and laundry rooms. Cement board does not swell or break down when it gets wet, unlike drywall or plywood. This makes it a great choice for tile underlayment and other hard jobs.
Here are some important properties that make cement board a good pick:
Moisture Resistance: Cement board takes in much less water than drywall or plywood. It helps stop water damage, mold, and mildew. You can use it in damp rooms, but always seal the joints and edges for best results.
Strength: The thick structure and glass-fiber mesh make cement board able to hold a lot of weight. You can use it for walls, floors, and even some roofs.
Fire Resistance: Many builders call cement board a fire-resistant cement board. It does not burn or let out bad fumes, so it is safer for your house.
Long Lifespan: Cement board lasts a long time and does not need much care. It keeps its shape and strength even in tough spots.
Feature | Cement Board | Drywall | Plywood |
|---|---|---|---|
Water Resistance | High | Low | Moderate |
Mold Resistance | Excellent | Poor | Moderate |
Structural Strength | High | Low | Moderate |
Fire Resistance | High | Low | Low |
Tests show that cement board stays strong after heat and water. The glass-fiber mesh and cement mix help the board stand up to hits and bending. If you use cement board with less recycled fiber, it can last even longer outside.
You can trust cement board as a water-resistant material for new buildings and remodels. It works better than drywall and plywood in wet places. You also know it will not get damaged by water or fire easily.
Types of Cement Board
When you check out cement board types, you see many choices. Each one works best for certain jobs. Let’s look at the main kinds you will find in 2025.
Fibre Cement Board
Fibre cement board is used in homes and businesses a lot. It is made from cement, cellulose fibers, silica sand, and water. Factories use steam to make it strong. This board does not get damaged by water, fire, or termites. It stays flat and does not change shape. You can use it for walls, floors, countertops, and under roofs. Many people like fibre cement board because it blocks sound and heat. You can use it inside or outside. You can paint it or add texture for a special look. After you put it in, you do not need to do much to keep it nice.
Note: Fibre cement board is safer than wood or old asbestos boards. It lasts longer and is a better choice.
Cement Backer Board
Cement backer board is also very common. People use it under tile in wet places like bathrooms and kitchens. It has Portland cement, sand, aggregate, and fiberglass mesh. This board gives a strong, water-resistant base for tile. It does not burn and keeps mold away. You can cut it to fit and put it in place easily. It is best for floors, walls, and countertops under tile.
Here is a table to help you pick the right board:
Aspect | Cement Backer Board | Fibre Cement Board |
|---|---|---|
Composition | Portland cement, aggregate, fiberglass mesh, sand, lightweight concrete | Cement, reinforcing fibres (e.g., cellulose fibre), silica sand, water, cured under high-pressure steam |
Moisture Resistance | Made to stop water, good for tile jobs | Water resistant, dries fast, does not break down in water |
Fire Resistance | Will not burn | |
Termite Resistance | Not listed | Stops termites |
Dimensional Stability | Does not swell or bend | Stays the same size, does not shrink or swell |
Typical Uses | Under tile, mostly in wet rooms | Used for more things: walls, floors, countertops, roofs, inside and outside |
Specialty Boards
Some jobs need a special cement board. Groove fiber cement board adds cool looks to walls. Calcium silicate boards protect against fire in ceilings and walls. The Dryvit Direct-Applied Cement Board MD™ system is good for outside walls. It uses cement board with coatings to keep out water and weather. There are also cement bonded particle boards, wood wool cement boards, and wood strand cement boards. These boards give extra strength, block sound, or let you try new designs.
Tip: Pick the cement board that fits your job. Special boards can fix problems that regular boards cannot.
Where is Cement Board Used
Cement board is a very useful building material. You can use it in many places inside and outside your house. If you ask, “where is cement board used,” you will find it in bathrooms, kitchens, floors, and even on outside walls. Let’s see the most common ways people use cement board in 2025.
Bathrooms and Showers
Cement board is often put behind tile in showers and around tubs. Builders pick it because it does not get weak in wet places. You can put cement board over a plastic sheet or right on wall studs. Many people add a waterproof layer on top or use a special sheet like Schluter Kerdi. Some cement boards already have a waterproof layer.
Cement board gives a flat, strong base for tile.
It helps stop mold, water damage, and other problems.
Paper-faced drywall is not allowed here because it can fall apart and grow mold.
Tip: Cement board is water resistant, but not totally waterproof. Always seal the joints and use extra waterproofing in the wettest spots.
Kitchens and Countertops
Cement board works great under kitchen backsplashes and countertops. You can use it as a base for tile or stone. It handles heat and water better than plywood or particle board. This means your kitchen surfaces last longer and stay flat.
Property | Cement Particle Board | Plywood |
|---|---|---|
Composition | Hardwood veneers glued in layers | |
Thickness | Usually 25 mm (thicker, more stable) | Usually 12 mm (thinner) |
Moisture Resistance | High (built-in moisture resistance) | Low (can warp and get damaged) |
Heat Resistance | Good heat resistance | Lower heat resistance |
Load Bearing | Higher load-bearing capacity | Lower load-bearing capacity |
You can put in cement board for kitchen backsplashes by cutting it to fit, screwing it in with special screws, and sealing the joints with tape and mortar. This gives you a strong, water-resistant surface for tile. Cement board also keeps your kitchen safe from water leaks and heat from cooking.
Plywood and particle board need careful sealing to stop water damage.
Cement board resists water and heat, so you do not have to worry as much about spills or steam.
Many experts now use cement board for floors and countertops in kitchens because it lasts longer.
Flooring Underlayment
You can use cement board under tile floors. It gives a solid, steady base that keeps tiles from cracking. Cement board for floors is very strong, so it holds up heavy things and does not bend. This is important for bathroom floors, laundry rooms, and other places with tile.
Cement board helps stop cracked mortar or tile.
It works better than plywood or drywall under tile because it does not swell when wet.
You can use it in kitchens, bathrooms, entryways, and laundry rooms.
Note: Cement board is water resistant but not waterproof. Always use a waterproof layer in very wet areas like showers or near tubs.
Exterior Siding and Soffits
Cement board is a top pick for outside walls. You can use it on outside walls, soffits, and even roof decks. Fiber cement board stands up to rain, wind, sun, and bugs. It does not rot, bend, or burn easily. This makes it a smart choice for homes in tough weather.
Fiber cement board lasts much longer than wood or vinyl siding.
It resists fire, bugs, and weather damage.
You do not need to paint or seal it as much as wood.
Cement board keeps its color and shape for many years.
Siding Type | Lifespan (Years) | Durability and Maintenance Notes |
|---|---|---|
Wood Siding | 15 to 40 | Needs lots of repainting and sealing; can rot, bend, or crack. |
Fiber Cement Siding | Resists rot, bugs, fire, and hits; does not swell or bend; needs little care. |
Tip: For outside walls, always seal edges and joints to keep out water. This helps stop mold and keeps your siding looking good.
Cement board also works well for inside walls and ceilings in basements, garages, and laundry rooms. You can use it anywhere that needs extra strength or moisture resistance. With so many uses, cement board is now a key material for new buildings.
Cement Board vs. Other Materials
Drywall
You may see drywall used in many homes. It works well for most dry rooms. However, drywall does not hold up in wet places. When you compare cement board to drywall, you notice big differences. Cement board resists water, mold, and mildew. Drywall can warp, sag, or grow mold if it gets wet. You should use cement board in bathrooms, showers, and kitchens where water is a problem.
Here is a table to help you see the main differences:
Performance Aspect | Cement Board | Drywall |
|---|---|---|
Moisture Resistance | Highly moisture resistant; ideal for wet areas | Prone to warping and mold in wet areas |
Strength & Durability | Strong and supports heavy tile | Less durable; not for heavy loads |
Fire Resistance | High fire resistance | Some fire resistance |
Installation & Cost | Harder to install, costs more | Easier and cheaper to install |
Tip: Always pick cement board for tile jobs in wet rooms. Drywall works best in dry spaces.
Plywood
Plywood is another common building material. You might use it for floors or walls. Plywood is made from thin wood layers glued together. It can flex and warp if it gets wet or if the temperature changes. Cement board stays flat and strong, even when the floor moves a little. You get better tile adhesion with cement board. Plywood needs extra glue or mortar to hold tiles.
Aspect | Cement Board | Plywood |
|---|---|---|
Stability & Rigidity | Very stable and rigid | Can flex and warp |
Moisture Resistance | Highly resistant to water | Can get damaged by water |
Adhesion | Tiles stick well | Needs extra bonding agents |
Durability | Lasts long in wet and busy areas | Best for dry, stable places |
If you want a floor that lasts, choose cement board under your tiles. You will avoid cracked tiles and loose grout.
Greenboard
Greenboard looks like drywall but has water-resistant additives. You may think it works in wet rooms, but it has limits. Greenboard handles humidity better than regular drywall. It does not work well in places with lots of water, like showers or tub walls. Cement board gives you much better protection in these spots.
Greenboard works in humid rooms, such as bathrooms and kitchens.
It resists mold better than drywall.
Cement board is stronger and blocks more water.
Both greenboard and cement board beat drywall for moisture resistance.
Cement board is best for very wet areas and tile jobs.
Note: Greenboard can fail if water gets behind it. You may see mold or damage if you use it in showers. Cement board is the safer choice for wet and high-impact areas.
Installation Tips
Cutting and Handling
When you cut cement board, you want smooth edges and less dust. You can use many tools for this job. The table below shows which tool is best for each task:
Tool/Technique | Dust Minimization | Breakage Minimization | Additional Notes |
|---|---|---|---|
Utility Knife | Makes no dust | Cut on the back, snap like drywall | Cheapest and easiest; needs hand strength |
Snapper Shear Pro | Makes very little dust | Cuts shapes easily | Costs more; good if you cut a lot |
Oscillating Tool (diamond blade) | Makes little dust, good inside | Cut on the back | Costs more; good for square holes and indoor jobs |
Circular Saw (with dust extractor & guide rail) | Makes lots of dust, needs dust collector | Cut on the back, set blade depth right | Use outside only; wear safety gear; cuts fast and straight |
Jigsaw (coarse blade) | Makes some dust, less than circular saw | Use a guide to stop chipping | Safer than circular saw; slower; good for curves |
Pad Saw (drywall saw) | Makes less dust than power saws | Good for square holes | Good for cutting holes; use by hand |
Circle Cutter | Makes dust (power tool) | N/A | Best for round holes; works fast |
Work outside or in a place with fresh air. Wear gloves, goggles, and a mask to stay safe from dust. Cover floors and furniture with plastic if you work inside. Keep your area tidy so you do not trip.
Fastening and Sealing
You must attach cement board tightly. Use special screws for cement board and put them 8 inches apart. Always put the cement board on a thin layer of thinset mortar when you work on floors. This keeps the board steady and stops it from moving.
Seal the joints in wet places with thinset mortar and cement board tape. Push thinset into small spaces before taping. Put a thin layer of thinset over the tape to make it flat. In showers or other wet spots, put a waterproof layer like RedGard or Kerdi on top of the cement board. This keeps water out and stops mold.
Sealant Type | Key Characteristics | Benefits for Wet Areas |
|---|---|---|
Sticks well, resists water, lasts long | Great for places that stay wet | |
Sikasil Silicone | Sticks well, keeps color, handles heat | Looks good and stays strong |
Tip: Cement board does not soak up much water but is not fully waterproof. Always use a waterproof layer in showers and wet places.
Common Mistakes
People sometimes make mistakes when putting in cement board. Here are some things you should not do:
Not using thinset mortar under the cement board. This makes the board move and tiles can crack.
Not using tape and thinset on the seams. This makes the surface weak and lets water in.
Putting cement board right on the floor without thinset. This does not give enough support.
Using the wrong glue, like Liquid Nails, instead of thinset mortar.
Not following the instructions from the maker.
If you skip the waterproof layer in showers, water can get behind the wall. This can rot wood and cause mold. Always do the steps right to keep your project safe and strong.
When you use cement board, you get lots of good things. It is strong and does not get damaged by water. It also helps keep your home safe from fire. Before picking a type, think about how long it will last, how much it costs, and how hard it is to put in. In wet places, always use more waterproofing and follow what the maker says. If you check your cement board often and take care of it, it will last a long time.
FAQ
Can you use cement board as a waterproof barrier?
Cement board resists water but does not stop it completely. You should always add a waterproof membrane or coating in showers or wet areas. This extra step keeps your walls safe from leaks and mold.
How do you cut cement board without making a mess?
You can score the board with a utility knife and snap it for straight cuts. For curves or holes, use a jigsaw or circular saw with a dust mask. Always cut outside or in a well-ventilated area.
Can you paint cement board directly?
Yes, you can paint cement board. Make sure the surface is clean and dry. Use a primer made for masonry or cement. Then, apply exterior-grade paint for the best results.
How long does cement board last?
Cement board lasts for decades if you install it correctly. It does not rot, warp, or burn. You can expect it to stay strong and stable in both wet and dry areas.
Tip: Always follow the manufacturer’s instructions for the best performance and longest lifespan.