Is HardiePlank Considered Non-Combustible?

Hardieplank, a popular brand of siding, is often suspected of being combustible due to its composition containing fiber cement, which is partially made of cellulose fibers derived from wood. However, the question "is Hardieplank considered non-combustible?" has a more nuanced answer.

Hardieplank is technically not classified as a completely non-combustible material, but its combustion properties and performance under fire make it a top choice for construction where fire resistance is critical. Let's explore this fascinating topic.

Composition of Hardieplank and Combustibility

The primary components of Hardieplank are cellulose fibers (wood pulp), cement, sand, and water.Wood is inherently combustible, leading many to assume that Hardieplank is combustible. However, the presence of cement and the unique manufacturing process significantly alters this property.

Cement acts as a binder andheat sink, making it difficult for Hardieplank to ignite and burn like wood. Additionally, the high density of Hardieplank and its low organic content further impede combustion.

Fire-Resistant Properties of Hardieplank

Hardieplank is not classified as non-combustible, but it demonstrates exceptional fire-resistant properties. It has a 5-hour fire-resistance rating per ASTM E119, the standard for laboratory scale fire resistance tests.This means that in the event of a fire, Hardieplank can hold its structure for up to 5 hours, providing valuable time for evacuation and fire suppression.

Moreover, Hardieplank has a Class A fire rating, the highest available, according to ASTM E 84, which tests surface burning characteristics of building materials. This indicates that Hardieplank is one of the most fire-resistant materials available for exterior building claddings.

Resistant to Common Fire Sources

Hardieplank holds up exceptionally well against common fire sources. It resists ignition from embers and small flames, and it doesn't contribute significantly to the spread of flames. This is why it's widely used in areas prone to wildfires and for buildings needing to meet strict fire safety standards.

For instance, Hardieplank is the only lap siding on the market that's recognized by the California State Fire Marshal as providing resistance to firebrand (ember) impacts.This is a testament to its superior fire resistance compared to other sidings.

Hardieplank vs. Completely Non-Combustible Materials

While Hardieplank is not a completely non-combustible material, it outperforms other non-combustible options in many respects. Non-combustible materials, such as metal or concrete, can still burn under extreme heat, warp, or even explode due to rapid temperature changes.

On the other hand, Hardieplank holds its structure, doesn't melt, warp, or expand during a fire. It also provides better insulation and durability than many non-combustible materials, making it an attractive choice for new construction and retrofits where fire resistance is paramount.

In conclusion, Hardieplank, despite not being classified as non-combustible, demonstrates exceptional fire resistance, making it a reliable choice in construction projects where fire safety is a prime concern. Its unique combination of durability, high insulation, and remarkable fire performance sets it apart from other materials, both combustible and non-combustible.