Technical Information | Fire Resistive Ratings
(Excerpted from Take Credit for a Good Design, published by CMACN)
Desert Block Co., Inc. supplies this information as an educational aid in understanding the benefits of concrete masonry construction and our products. It is the responsibility of the user to obtain engineering or other advisory services from licensed professionals as the basis for incorporating into any project any information, detail, or product offered herein.
Concrete masonry is probably the best-suited construction material available in the marketplace today for use in constructing fire-resistive walls in buildings. Concrete masonry means confidence: confidence that the fire protection you design is the fire protection you get; confidence that the fire-resistive wall will be there when its needed; confidence that it is safe because it cannot burn and is structurally stable; confidence that it reduces liability because of its inherent fire resistance and noncombustibility and because it shows that the designer has expended the extra effort to provide good fire protection; confidence that it has an inherent safety factor built in. Concrete masonry fire resistance is much more durable and lasting and certainly more stable in response to fire than other types of materials and assemblies. A little bit of concrete masonry can go a long way toward providing a reasonable level of fire protection.
Concrete masonry makes even more sense since it has great utility in the construction business. Its multi-functional characteristics coupled with its durability and low maintenance make it an ideal construction material. It can satisfy the needs of a building designer or owner on many fronts. Properly designed and located concrete masonry fire-resistive walls can provide cost effective functional structures that will withstand the ravages of fire.
Concrete masonry is cost effective. Because it is multi-functional, its installation costs are not truly representative of its actual impact to the overall costs of the construction project. Where other materials or multitudes of assemblies of materials may be necessary to perform the functional needs of the building desired by the owner, concrete masonry walls can be used to satisfy those needs in one package. The life cycle costs of concrete masonry are extremely low compared to many other construction materials. When such costs as maintenance, insurance, and business interruption are included, it becomes obvious that concrete masonry is a truly cost effective product.
A professional designer who desires to serve his client well by providing a cost-effective, functional, and aesthetically pleasing structure would do well to integrate concrete masonry into the total building design. By selecting concrete masonry, the designer will be able to instill confidence in the owner that his building will endure and withstand the ravages of fire in order to protect the owner's investment and limit his liability.
FIRE RATINGS OF CONCRETE MASONRY WALLS
EXPANDED CLAY, SHALE OR SLATE AGGREGATES |
Width (W) |
Fire Resistance Ratings |
|
|
Nominal |
Specified |
Partial Grouted or Hollow Masonry |
Solid Grouted Masonry |
4" |
3 5/8" |
Less than 1 Hour |
2 Hours |
6" |
5 5/8" |
1 Hour |
4 Hours |
8" |
7 5/8" |
2 Hour |
4 Hours |
10" |
9 5/8" |
2 Hour |
4 Hours |
12" |
11 5/8" |
3 Hour |
4 Hours |
|
FIRE RATINGS OF CONCRETE MASONRY WALLS
LIMESTONE, CINDERS OR AIR-COOLED SLAG AGGREGATES
|
Width (W) |
Fire Resistance Ratings |
|
|
Nominal |
Specified |
Partial Grouted or Hollow Masonry |
Solid Grouted Masonry |
4" |
3 5/8" |
Less than 1 Hour |
1 Hours |
6" |
5 5/8" |
1 Hour |
3 Hours |
8" |
7 5/8" |
1 Hour |
4 Hours |
10" |
9 5/8" |
2 Hour |
4 Hours |
12" |
11 5/8" |
3 Hour |
4 Hours |
|
FIRE RATINGS OF CONCRETE MASONRY WALLS
CALCAREOUS OR SILICEOUS AGGREGATES |
Width (W) |
Fire Resistance Ratings |
|
|
Nominal |
Specified |
Partial Grouted or Hollow Masonry |
Solid Grouted Masonry |
4" |
3 5/8" |
Less than 1 Hour |
1 Hours |
6" |
5 5/8" |
1 Hour |
3 Hours |
8" |
7 5/8" |
1Hour |
4 Hours |
10" |
9 5/8" |
2 Hour |
4 Hours |
12" |
11 5/8" |
2 Hour |
4 Hours |
|
Notes:
1. The fire resistive ratings of the various thicknesses of concrete masonry walls (reinforced or solid grouted) have been calculated based on Uniform Building Code Table No. 7-B, Items 6-1.1 through 6-1.4 by the equivalent thickness method using the minimum thickness of the face shells and webs specified in UBC Standard No. 21-4.
2. For determining the fire resistance ratings of concrete masonry walls using blended aggregates, refer to Footnote 17 to Table No. 7-B of the UBC.
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