31B-267 57 Center code review exterior walls (2)912.6 Exterior wall fire-resistance ratings. Hazard categories in regard to fire-resistance ratings
of exterior walls shall be in accordance with Table 912.6.
The third hazard classification area is the exposure of the exterior walls, relating to the need to
protect surrounding buildings from fire conflagration. This section requires that hazard
categories for fire exposure of exterior walls are established in accordance with Table 912.6.
See also the commentary for Table 912.6. Table 912.6 groups the uses in the relative hazard
levels based primarily on the requirements of Section 704, as well as Table 602 of the IBC.
912.6.1 Exterior wall rating for change of occupancy classification to a higher hazard category.
When a change of occupancy classification is made to a higher hazard category as shown in
Table 912.6, exterior walls shall have fire resistance and exterior opening protectives as
required by the International Building Code.
Exception: A 2-hour fire-resistance rating shall be allowed where the building does not exceed
three stories in height and is classified as one of the following groups: A-2 and A-3 with an
occupant load of less than 300, B, F, M or S.
Consistent with the general rule throughout this chapter for a change of occupancy classification
to a higher hazard category, the exterior wall rating is required to meet the ratings called for by
the IBC for new construction. The exception is somewhat academic. These occupancy
classifications are never required to have a 3-hour fire-resistance rating on exterior walls.
912.6.2 Exterior wall rating for change of occupancy classification to an equal or lesser hazard
category. When a change of occupancy classification is made to an equal or lesser hazard
category as shown in Table 912.6, existing exterior walls, including openings, shall be accepted.
The exterior wall fire-resistance rating is allowed to remain without change when the change of
occupancy classification is to an equal or lesser hazard category. Again, this is in keeping with
the philosophy that no change is needed when the hazard to the building is not increased by the
change or alteration of the building.
912.6.3 Opening protectives. Openings in exterior walls shall be protected as required by the
International Building Code. Where openings in the exterior walls are required to be protected
because of their distance from the property line, the sum of the area of such openings shall not
exceed 50 percent of the total area of the wall in each story.
Exceptions:
1. Where the International Building Code permits openings in excess of 50 percent.
2. Protected openings shall not be required in buildings of Group R occupancy that do not
exceed three stories in height and that are located not less than 3 feet (914 mm) from the
property line.
3. Where exterior opening protectives are required, an automatic sprinkler system throughout
may be substituted for opening protection.
4. Exterior opening protectives are not required when the change of occupancy group is to an
equal or lower hazard classification in accordance with Table 912.6.
Commentary, 912.6.3:
At first glance, this provision would seem to contradict the provision in Section 912.6.2, which
states that opening protectives need not change for the change of occupancy to an equal or
lesser hazard classification. This is, however, reflected in Exception 4 at any rate. It should be
remembered, however, that this would apply in all cases where change is to a higher hazard
category as described in Section 912.6.1. The significance of this section is that it imposes a
maximum area of openings to be 50 percent of the wall area when the fire separation distance
requires opening protectives, contrary to the percentages given by Table 705.8 of the IBC.