FIRE RATINGS for CONCRETE MASONRY UNITS
Using Equivalent Thickness Method
Conforms with:
National Concrete Masonry Association (NCMA) Tek 7-1A (2003) International Building Code (2006)
| FIRE RATINGS - HOURS | |||||||
| UNIT WIDTH | BLOCK TYPE | FACE SHELL |
% SOLID |
EQUIVALENT THICKNESS |
NORMAL WEIGHT CONCRETE (Siliceous Gravel) |
MEDIUM WEIGHT (105-125lb per cubic ft blended) |
LIGHT WEIGHT (Under 105lbs per cubic ft) (Expanded clay, shale or slate) |
| 4" 4" |
3 Core Regular Solid |
1.0" Solid |
76% 100% |
2.7 3.6 |
3/4 1-1/2 |
1 1-1/2 |
1 1-1/2 |
| 6" 6" 6" |
2 Core Regular 3 Core 75% Solid Solid |
1.06" 2.0" Solid |
56% 75% 100% |
3.1 4.2 5.6 |
1 2 3 |
1 2 3-3/4 |
1 2 4 |
| 8" 8" 8" 8" 8" |
2 Core Regular 2 Core 58% Solid 2 Core 62% Solid 3 Core 75% Solid Solid |
1.25" 1.5" 1.5" 2.25" Solid |
53% 58% 62% 75% 100% |
4.0 4.4 4.7 5.7 7.6 |
1-1/2 2 2 3 4 |
2 2 2 3 4 |
2 2 3 4 4 |
| 10" | 2 Core Regular | 1.25" | 51% | 4.9 | 2 | 2 | 3 |
| 12" 12" |
2 Core Regular 2 Core 56% Solid |
1.5" 2.125" |
50% 50% |
5.8 6.5 |
3 4 |
3 4 |
4 4 |
Most of these units are normally stocked by A. Jandris & Sons, Inc.
Note:
Increasing Fire Ratings: Walls composed of hollow concrete masonry units having a nominal thickness of 8 inches or greater and having a fire resistance rating of at least 2 hours shall be classified as 4 hours when the hollow spaces are completely filled with perlite or vermiculite, grout or a material such as expanded slag, clay shale, slate or sand.
