1509.2.1
Height above roof. A
penthouse or other projection above the roof in structures of other than Type I
construction shall not exceed 28 feet (8534 mm) above the roof where used as an
enclosure for tanks or for elevators that run to the roof and in all other
cases shall not extend more than 18 feet (5486 mm) above the roof.
1509.2.2
Area limitation. The
aggregate area of penthouses and other rooftop structures shall not exceed
one-third the area of the supporting roof. Such penthouses shall not contribute
to either the building area or number of stories as regulated by Section 503.1.
The area of the penthouse shall not be included in determining the fire area
defined in Section 902.
1509.2.3
Use limitations. A penthouse, bulkhead or any
other similar projection above the roof shall not be used for purposes other
than shelter of mechanical equipment or shelter of vertical shaft openings in
the roof. Provisions such as louvers, louver blades or flashing shall be made
to protect the mechanical equipment and the building interior from the
elements. Penthouses or bulkheads used for purposes other than permitted by
this section shall conform to the requirements of this code for an additional
story. The restrictions of this section shall not prohibit the placing of wood
flagpoles or similar structures on the roof of any building.
1509.2.4
Type of construction.
Penthouses shall be constructed with walls, floors and roof as required for the
building.
Exceptions:
1. On buildings of Type I construction, the
exterior walls and roofs of penthouses with a fire separation distance of more
than 5 feet (1524 mm) and less than 20 feet (6096 mm) shall be of at least
1-hour fire resistance-rated noncombustible construction. Walls and roofs with
a fire separation distance of 20 feet (6096 mm) or greater
shall be of noncombustible construction. Interior framing and walls shall be of
noncombustible construction.
2. On
buildings of Type I construction two stories above grade plane
or less and Type II construction, the exterior walls and roofs of penthouses
with a fire separation distance of more than 5 feet (1524 mm)
and less than 20 feet (6096 mm) shall be of at least 1-hour
fire-resistance-rated noncombustible or fire-retardant-treated
wood construction. Walls and roofs with a fire separation
distance of 20 feet (6096 mm) or greater shall be of noncombustible or
fire-retardant-treated wood construction. Interior framing and
walls shall be of noncombustible or fire-retardant- treated wood
construction.
3. On buildings of
Type III, IV and V construction, the exterior walls of penthouses with a fire
separation distance of more than 5 feet (1524 mm) and less than 20 feet (6096
mm) shall be at least 1-hour fire-resistance-rated construction. Walls with a
fire separation distance of 20 feet (6096 mm) or greater from a common property
line shall be of Type IV construction or noncombustible, or
fire-retardant-treated wood construction. Roofs shall be constructed of
materials and fire-resistance rated as required in Table 601 and Section 603,
Item 25.3. Interior framing and walls shall be Type IV construction or
noncombustible or fire-retardant-treated wood construction.
4. On buildings of Type I construction,
unprotected noncombustible enclosures housing only mechanical equipment and
located with a minimum fire separation distance of 20 feet (6096 mm) shall be
permitted.
5. On buildings of Type
I construction two stories or less above grade plane or Type II, III, IV and V
construction, unprotected noncombustible or fire-retardant-treated wood
enclosures housing only mechanical equipment and located with a minimum fire
separation distance of 20 feet (6096 mm) shall be permitted.
6. On one-story buildings, combustible
unroofed mechanical equipment screens, fences or similar enclosures are
permitted where located with a fire separation distance of at least 20 feet
(6096 mm) from adjacent property lines and where not exceeding 4 feet (1219 mm)
in height above the roof surface.
7. Dormers shall be of the same type of
construction as the roof on which they are placed, or of the exterior walls of
the building.
