Code of Massachusetts Regulations › 780 CMR - STATE BOARD OF BUILDING REGULATIONS AND STANDARDS › Chapter 15 - Roof Assemblies and Rooftop Structures › Section 1509 - ROOFTOP STRUCTURES › Subsection 1509.2 - Penthouses

Current through Register 1525, July 5, 2024
A
penthouse
or
penthouses
in compliance with Sections 1509.2.1 through 1509.2.4 shall be considered as a
				  portion of the
story
below.
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.