CMU Fire Rating Chart
Ernest Maier CMU Complying with IBC 2003
Equivalent Thickness Table 6.0 – Tek Note 7.01D
2005 Supplement
| Fire Resistance | Nominal Size | ASTM | Solid Materials | Equivalent Thickness (in) |
| ½ Hour | 2x8x16 3x8x16* | C-145 C-90 | 100% 79% | 1.9 1.9 |
| ¾ Hour | 4x8x16 3x8x16 | C-90 C-145 | 65% 100% | 2.4 2.6 |
| 1 Hour | 4x8x16 4x8x12 4x8x16* | C-90 C-90 C-145 | 79% 73% 78% | 2.7 2.7 2.8 |
| 1 ½ Hours | 6x8x16 8x8x16 Normal Weight | C-90 C-90 | 54% 50% | 3.0 3.8 |
| 2 Hours | 2-1/4×3-3/4×8** 4x8x16 4x8x12 8x8x24*** 6x8x16*** 8x8x16 Lightweight*** | C-55 C-145 C-145 C-90 C-90 C-90 | 100% 100% 100% 52% 64% 50% | 3.6 3.6 3.6 3.7 3.6 3.8 |
| 3 Hours | 8x8x16 10x8x16 | C-90 C-90 | 63% 50% | 4.8 4.8 |
| 4 Hours | 8x8x16 8x8x12 12x8x12*** 12x8x16 6x8x16 8x8x12 8x8x16 | C-145 C-145 C-90 C-90 C-145 C-145 C-145 | 75% 75% 55% 50% 100% 100% 100% | 5.7 5.7 5.4 5.6 5.6 7.6 7.6 |
CMU Fire Resistance Calculator
* BMS 92 – National Bureau Standard
** Concrete Brick
Primary Aggregates – Expanded Shale and/or Pumice
Above Blocks Plastered on One Side with 1/2 inch 1:3 Gypsum and Sand Plaster adds 1/2 Hour to Fire Rating
VP of MasonryTed Kelly
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