Building Design and Construction Handbook - Merritt - Ventech!

3.34 SECTION THREE
(‘‘Life Safety Handbook’’ and ‘‘Fire Protection Handbook,’’ National Fire Protection
Association, Quincy, Mass.)
3.5.6 Fire-Resistance Classification of Buildings
Although building codes classify buildings by occupancy and construction, there is
no universal standard for number of classes of either occupancy or construction.
Table 3.3 lists some typical occupancy classifications and associates approximate
fire loads with them. This table should be used only as a guide. For a specific
project refer to the applicable local code. Note, however, that codes do not relate
life-safety hazards to the actual fire load, but deal with them through requirements
for exit arrangements, interior finishes, and ventilation.
Types of construction may be classified by a local building code as follows but
may have further subdivisions, depending on fire-resistance requirements:
1. Fire-resistive construction
2. Protected noncombustible construction
3. Unprotected noncombustible construction
4. Heavy-timber construction
5. Ordinary construction
6. Wood-frame construction
The required fire resistance varies from 4 hr for exterior bearing walls and interior
columns in the highest fire resistive class to 1 hr for walls and none for columns
in the wood-frame construction class.
TABLE 3.3 Approximate Fire Loads for
Various Occupancies*
Occupancy class
Typical average
fire load including
floors and trim, psf
Assembly 10.0
Business 12.6
Educational 7.6
High hazard †
Industrial 25.0
Institutional 5.7
Mercantile 15–20
Residential 8.8
Storage 30.0
* From National Institute of Standards and Technology
Report BMS92, ‘‘Classifications of Building
Constructions,’’ Government Printing Office, Washington.
D.C. 20402.
† Special provisions are made for this class, and
hazards are treated for the specific conditions encountered,
which might not necessarily be in proportion
to the actual fire load.