Is cement backer board heat resistant?

Author: Cathryn Corwin  |  Last update: Friday, July 10, 2026

Yes, HardieBacker® 1/4" Cement Board is deemed noncombustible when tested to ASTM E 136 and can be used in conjunction with other noncombustible materials around a fireplace. This does not mean that clearances to combustible building materials can be reduced by using HardieBacker 1/4".

How much heat can cement board withstand?

A high density cement board reinforced with inorganic fibers, NAD-11 is suitable for applications requiring continuous operation in temperatures up to 500°C (932°F). NAD-11 is dimensionally stabile, non-combustible, chemically inert, and it retains its mechanical strength at temperature.

Can cement board be used as a heat shield?

The industry's solution for heat shields

PermaBASE cement boards are the industry-preferred choice. Installation-ready and easy-to-use, PermaBASE® cement boards eliminate the need for field fabrication, saving time while allowing for enhanced performance and wood-burning stove placement closer to the wall.

Does heat transfer through cement board?

Cement board typically has a thermal conductivity (k-value) ranging from 0.18 to 0.35 Watts per metre-Kelvin (W/mK). Compared to concrete (1.0-1.8 W/mK), this relatively low thermal conductivity allows cement boards to provide some insulation value.

Are cement backer boards fireproof?

While cement board is highly resistant to fire, it is not completely fireproof. Over prolonged exposure to intense heat, even cement board will eventually begin to deteriorate. However, its ability to resist fire for an extended period makes it an invaluable component in fire-rated assemblies.

5 reasons to choose Hardie Backer Boards

Can I use cement board around a fireplace?

PermaBASE® Cement Board offers a simpler, cleaner way to install fireplace insert surrounds that saves installation time. The boards arrive ready to be installed, no jobsite preparation needed.

Is HardieBacker 500 cement board fireproof?

HardieBacker® cement board has been evaluated by the BBA and approved with certificate no. 04/4100. The products meet the European standard for fibre cement - EN 12467 and its reaction to fire, in accordance with EN 13501-1, is A1,S1-d0. The product is therefore classified as fully non-combustible.

What's the difference between cement board and backer board?

Fiber cement board is a thin layer of concrete that is installed as a sturdy surface subfloor for tile setting. Backer board is made up of a sheet of cement mixed with sand that has a fiberglass mesh placed on each side of the board for durability.

Does cement crack under heat?

Changes in the temperature of concrete can cause cracking. As the concrete gets hotter, it expands; as concrete gets cooler, it contracts. This is similar for many other materials you have probably learned about. If the concrete wants to expand or contract but can't, it will most likely crack.

Is a hardie backer board heat resistant?

Yes, HardieBacker® 1/4" Cement Board is deemed noncombustible when tested to ASTM E 136 and can be used in conjunction with other noncombustible materials around a fireplace.

Can I use Durock behind a wood stove?

DUROCK Cement Board is listed by Underwriters Laboratories, Inc., for use with UL-listed solid-fuel room heaters and fire- place stoves.

How do you make cement heat resistant?

Calcium Aluminate cement and Lime will work the best as the cement in hot cooking conditions- This applies to refractory concrete as well as to heat resistant mortars. (Lime is sometimes mixed into fire clays. This is mixed like a normal cement based mortar, but with half the cement replaced with the lime.

Does it matter which side of the hardie board faces out?

Install smooth side up. Install HardieBacker boards perpendicular to subfloor panels. Never allow all four corners of boards to meet at one point.

What temperature is too hot for cement?

Fewer concrete problems indeed exist during the summer, but excessively hot temperatures can cause problems as well. If you intend to install concrete in temperatures around 90 degrees, you'll need to adjust the mix and installation process to accommodate the heat.

What is the maximum temperature for cement board?

H91 Cement Board Physical Properties:

Operating Temp - 1292º F/700º C. Compressive Strength - 16,675 psi ambient 15,310 psi (24 hrs @ 700º F) 14,020 psi (24 hrs @ 1000º F) Electrical Strength - 1.83 Kv/mm in air @ 200° F.

Can Durock cement board be used outside?

Durock Cement board can be used on exterior walls.

How heat resistant is cement?

Ranging from 1,000 to 1,800 degrees Celsius (1,800 to 3,300 degrees Fahrenheit), heat-resistant concrete outperforms conventional counterparts, making it ideal for furnaces, kilns, incinerators, and fireplaces.

Will concrete crack with fire?

While concrete blocks are resistant to fire, the materials are not entirely unaffected by high heat. Temperatures up to 420 degrees Celsius can cause the concrete to lose strength and break. At 600 degrees Celsius and above, concrete no longer possesses its full structural capacity.

Does wetting the concrete stop it from cracking?

Moist curing is a common method of concrete curing. It involves wetting the concrete slab often with water (5-7 times per day) for the first 7 days. This method ensures your concrete slab will be extremely strong and durable, because it allows the moisture to evaporate slowly, preventing cracks and shrinks.

Which is better, hardie board or cement board?

There are two major differences between the two for homeowners to consider: Hardie board is more lightweight and cement board is less expensive. If you're learning how to install fiber cement siding yourself, Hardie board might be a better option as it would be easier to manage compared to traditional cement board.

Does it matter which side of cement board you use?

The smooth side is ideal for mastic applications, as it increases adhesive coverage. The textured side is ideal for mortar applications, as it enhances bonding and reduces tile slip. That said, mastic or thin-set mortar can be used on either side of the board without compromising performance.

Can you tile straight onto cement board?

Can I Tile Directly Onto Cement Board? Yes, cement board is the perfect base for tiling, as it's waterproof and provides a smooth, even surface that won't be disturbed by moisture.

Can cement board withstand heat?

Performance in Extreme Heat

Fiber cement boards are non-combustible and can withstand high temperatures without losing their structural integrity. This makes them suitable for areas prone to extreme heat and fire hazards.

Can I use cement board behind my wood stove?

The industry's solution for heat shields

By using an approved heat shield system, the required distance between the stove and adjacent wall can be significantly reduced. PermaBASE® Building Products are the industry-preferred choice and the only cement board approved for heat shield applications.

How hot can a Hardie Backer board get?

I checked with Hardiebacker, their cement boards won't even burn below 750 degrees, and won't ignite below 1500.

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