CMU Fire Rating Chart
Ernest Maier CMU Complying with IBC 2003
Equivalent Thickness Table 6.0 – Tek Note 7.1
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 |
* 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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