Building Materials Fire Rating Classification Criteria

The classification standards for building materials' fire resistance typically follow international or national norms, which may vary by region. Here is a general outline of fire resistance classifications, but please note that specific standards might differ depending on the location:

1. **European Standard (EN 13501-1):**

   - **A1:** Non-combustible.

   - **A2:** Limited combustibility.

   - **B:** Combustible.

   - **C:** Highly flammable.

   - **D:** Flammable.

   - **E:** Extremely flammable.

   - **F:** Unable to be assessed by standard testing.

2. **Chinese National Standard (GB 8624-2012):**

   - **A1:** Non-combustible.

   - **A2:** No dripping during combustion.

   - **B1:** Hardly flammable.

   - **B2:** Combustible.

   - **B3:** Flammable.

   - **B4:** Extremely flammable.

3. **American Standard (ASTM E84):**

   - **Class A:** No dripping, Smoke Developed Index ≤25.

   - **Class B:** No dripping, Smoke Developed Index ≤450.

   - **Class C:** Dripping allowed, Smoke Developed Index ≤450.

4. **Australian Standard (AS/NZS 3837):**

   - **Group 1:** Non-combustible.

   - **Group 2:** Limited combustibility.

   - **Group 3:** Combustible.

These standards evaluate building materials' combustion performance, flame spread rate, and smoke production during a fire.

 In practical applications, compliance with local regulations and building codes is typically required for the fire resistance rating of construction materials.