International Building Code Section 509


International Building Code 509.1

General. The provisions in this section shall permit the
use of special conditions that are exempt from, or modify, the
specific requirements of this chapter regarding the allowable
heights and areas of buildings based on the occupancy classification
and type of construction, provided the special condition
complies with the provisions specified in this section for such
condition and other applicable requirements of this code.

International Building Code 509.2

Group S-2 enclosed or open parking garage with
Group A, B, M, R or S above. A basement and/or the first
story above grade plane of a building shall be considered as a
separate and distinct building for the purpose of determining
area limitations, continuity of fire walls, limitation of number
of stories and type of construction when all of the following
conditions are met:
1. The basement and/or the first story above grade plane is
of Type IA construction and is separated from the building
above with a horizontal assembly having a minimum
3-hour fire-resistance rating.
2. Shaft, stairway, ramp or escalator enclosures through the
horizontal assembly shall have not less than a 2-hour
fire-resistance rating with opening protectives in accordance
with Table 715.4.
Exception: Where the enclosure walls belowthe horizontal
assembly have not less than a 3-hour
fire-resistance rating with opening protectives in
accordance with Table 715.4, the enclosure walls
extending above the horizontal assembly shall be permitted
to have a 1-hour fire-resistance rating, provided:
1. The building above the horizontal assembly is
not required to be of Type I construction;
2. The enclosure connects less than four stories;
and
3. The enclosure opening protectives above the
horizontal assembly have a minimum 1-hour
fire protection rating.
3. The building above the horizontal assembly shall be permitted
to have multiple GroupAuses, each with an occupant
load of less than 300, or Group B, M, R or S uses.
4. The building below the horizontal assembly is a Group
S-2 enclosed or open parking garage, used for the parking
and storage of private motor vehicles.
Exceptions:
1. Entry lobbies, mechanical rooms and similar
uses incidental to the operation of the building
shall be permitted.
2. Multiple Group A uses, each with an occupant
load of less than 300, or Group B or M uses
shall be permitted, in addition to those uses
incidental to the operation of the building
(including storage areas), provided that the
entire structure below the horizontal assembly
is protected throughout by an approved automatic
sprinkler system.
5. The maximum building height in feet shall not exceed
the limits set forth in Section 503 for the building having
the smaller allowable height as measured from the grade
plane.

International Building Code 509.3

Group S-2 enclosed parking garage with Group S-2
open parking garage above. A Group S-2 enclosed parking
garage located in the basement or first story below a Group S-2
open parking garage shall be classified as a separate and dis-
tinct building for the purpose of determining the type of construction
when the following conditions are met:
1. The allowable area of the structure shall be such that the
sum of the ratios of the actual area divided by the allowable
area for each separate occupancy shall not exceed
1.0.
2. The Group S-2 enclosed parking garage is of Type I or II
construction and is at least equal to the fire-resistance
requirements of the Group S-2 open parking garage.
3. The height and the number of the floors above the basement
shall be limited as specified in Table 406.3.5.
4. The floor assembly separating the Group S-2 enclosed
parking garage and Group S-2 open parking garage shall
be protected as required for the floor assembly of the
Group S-2 enclosed parking garage. Openings between
the Group S-2 enclosed parking garage and Group S-2
open parking garage, except exit openings, shall not be
required to be protected.
5. The Group S-2 enclosed parking garage is used exclusively
for the parking or storage of private motor vehicles,
but shall be permitted to contain an office, waiting
room and toilet room having a total area of not more than
1,000 square feet (93 m2), and mechanical equipment
rooms incidental to the operation of the building.

International Building Code 509.4

Parking beneath Group R. Where a maximum
one-story above grade plane Group S-2 parking garage,
enclosed or open, or combination thereof, of Type I construction
or open of Type IV construction, with grade entrance, is
provided under a building of Group R, the number of stories to
be used in determining the minimum type of construction shall
be measured from the floor above such a parking area. The
floor assembly between the parking garage and the Group R
above shall comply with the type of construction required for
the parking garage and shall also provide a fire-resistance rating
not less than the mixed occupancy separation required in
Section 508.3.3.

International Building Code 509.5

Group R-2 buildings of Type IIIA construction. The
height limitation for buildings of Type IIIA construction in
Group R-2 shall be increased to six stories and 75 feet (22 860
mm) where the first-floor construction above the basement has
a fire-resistance rating of not less than 3 hours and the floor
area is subdivided by 2-hour fire-resistance-rated fire walls
into areas of not more than 3,000 square feet (279 m2).

[edit]International Building Code 509.6

Group R-2 buildings of Type IIA construction. The
height limitation for buildings of Type IIA construction in
Group R-2 shall be increased to nine stories and 100 feet (30
480 mm) where the building is separated by not less than 50
feet (15 240 mm) from any other building on the lot and from
lot lines, the exits are segregated in an area enclosed by a 2-hour
fire-resistance-rated fire wall and the first-floor construction
has a fire-resistance rating of not less than 11/2 hours.

International Building Code 509.7

Open parking garage beneath Groups A, I, B,Mand
R. Open parking garages constructed under Groups A, I, B,M
andRshall not exceed the height and area limitations permitted
under Section 406.3. The height and area of the portion of the
building above the open parking garage shall not exceed the
limitations in Section 503 for the upper occupancy. The height,
in both feet and stories, of the portion of the building above the
open parking garage shall be measured from grade plane and
shall include both the open parking garage and the portion of
the building above the parking garage.

Fire separation. Fire barriers constructed in accordance
with Section 706 or horizontal assemblies constructed
in accordance with Section 711 between the
parking occupancy and the upper occupancy shall correspond
to the required fire-resistance rating prescribed in
Table 508.3.3 for the uses involved. The type of construction
shall apply to each occupancy individually, except that
structural members, including main bracing within the open
parking structure, which is necessary to support the upper
occupancy, shall be protected with the more restrictive
fire-resistance-rated assemblies of the groups involved as
shown in Table 601. Means of egress for the upper occupancy
shall conform to Chapter 10 and shall be separated
from the parking occupancy by fire barriers having at least a
2-hour fire-resistance rating as required by Section 706 with
self-closing doors complying with Section 715 or horizontal
assemblies having at least a 2-hour fire-resistance rating
as required by Section 711, with self-closing doors complying
with Section 715. Means of egress from the open parking
garage shall comply with Section 406.3.

International Building Code 509.7.1

Fire separation. Fire barriers constructed in accordance
with Section 706 or horizontal assemblies constructed
in accordance with Section 711 between the
parking occupancy and the upper occupancy shall correspond
to the required fire-resistance rating prescribed in
Table 508.3.3 for the uses involved. The type of construction
shall apply to each occupancy individually, except that
structural members, including main bracing within the open
parking structure, which is necessary to support the upper
occupancy, shall be protected with the more restrictive
fire-resistance-rated assemblies of the groups involved as
shown in Table 601. Means of egress for the upper occupancy
shall conform to Chapter 10 and shall be separated
from the parking occupancy by fire barriers having at least a
2-hour fire-resistance rating as required by Section 706 with
self-closing doors complying with Section 715 or horizontal
assemblies having at least a 2-hour fire-resistance rating
as required by Section 711, with self-closing doors complying
with Section 715. Means of egress from the open parking
garage shall comply with Section 406.3.

International Building Code 509.8

Group B or M with Group S-2 open parking garage
above. Group B orMuses located in the basement or first story
below a Group S-2 open parking garage shall be classified as a
separate and distinct building for the purpose of determining
the type of construction when all of the following conditions
are met:
1. The basement or first story shall be Type I or II construction,
but not less than the type of construction required
for the open parking garage above. The height and area
of the basement or first story shall not exceed the limitations
in Section 503 for the Group B or M uses.
2. The height and area of the open parking garage shall not
exceed the limitations permitted under Section 406.3.
The height, in both feet and stories, of the open parking
garage shall be measured from grade plane and include
both the open parking garage and the basement or first
story.
3. Fire separation assemblies between the open parking
garage and the basement or first story use group shall
correspond to the required fire-resistance rating prescribed
by Table 508.3.3
4. Exits serving the open parking garage shall discharge
directly to a street or public way and shall be separated
from the basement or first story use group by not less
than 2-hour fire barriers constructed in accordance with
Section 706 or 2-hour horizontal assemblies constructed
in accordance with Section 711, or both, with opening
protectives in accordance with Table 715.4.