780005
1/19/01 780 CMR - Sixth Edition 113
GENERAL BUILDING LIMITATIONS
780 CMR 501.0 GENERAL
nd the
resence of an automatic sprinkler system.
780 CMR 502.0 DEFINITIONS
re in 780 CMR, have the meanings shown
erein.
Ar
horizontal projection of the roof or floor above.
Ba
"Story above
grade").
Gr
nd a point six feet (1829 mm) from the
building.
H
ere is not a ceiling, to the top of the roof
rafters.
M
el or levels are
located (see 780 CMR 505.0).
St
e of a floor and the upper surface
of the floor or roof next above (also see
Sto
idered as a story above
he basement is:
29 mm) above the
3. More than 12 feet (3658 mm) above the
f
780 CMR 503.0 GENERAL HEIGHT
itations fixed in Table
503, except as specifically modified by 780 CMR 5
an llowing
HAPTER 5C
501.1 Scope: The provisions of 780 CMR 5 control
the height and area of all structures hereafter
erected, and additions to existing structures based on
the type of construction, use group, frontage on open
space providing exposure protection and access to
structures for fire-fighting purposes, a
p
502.1 General: The following words and terms
shall, for the purposes of 780 CMR 5 and as used
elsewhe
h
ea, building: The area included within
surrounding exterior walls (or exterior walls and
fire walls) exclusive of vent shafts and courts.
Areas of the building not provided with
surrounding walls shall be included in the
building area if such areas are included within the
sement: That portion of a building which is partly
or completely below grade (see
ade plane: A reference plane representing the
average of finished ground level adjoining the
building at all exterior walls. Where the finished
ground level slopes away from the exterior walls,
the reference plane shall be established by the
lowest points within the area between the building
and the lot line or, where the lot line is more than
six feet (1829 mm) from the building, between the
building a
eight
Building: The vertical distance from grade plane
to the average height of the highest roof surface.
Story: The vertical distance from top to top of
two successive tiers of beams or finished floor
surfaces; and, for the topmost story, from the top
of the floor finish to the top of the ceiling joists or,
where th
ezzanine: An intermediate level or levels between
the floor and ceiling of any story with an
aggregate floor area of not more than _ of the area
of the room in which the lev
ory: That portion of a building included between
the upper surfac
"Mezzanine").
ry above grade: Any story having its finished
floor surface entirely above grade except that a
basement shall be cons
grade where the finished surface of the floor
above t
1. More than six feet (1829 mm) above grade
plane;
2. More than six feet (18
finished ground level for more than 50% of the
total building perimeter; or
inished ground level at any point.
AND AREA LIMITATIONS
503.1 General: The heights and areas of all
buildings and structures between exterior walls or
between exterior walls and fire walls, shall be
governed by the type of construction and the use
group classification as defined in 780 CMR 3 and 6
and shall not exceed the lim
d the fo sections:
Section Subject
402.7 Covered mall buildings
403.3.3.1 High-rise buildings
414.2 Airport traffic control towers
418.3.1.1
Retail Buildings
f electric, gas or
steam power, shall be exempt from the height and
rking
structures shall conform to the height and area
416.3 HPM facilities
Grain elevators
426.0 Bulk Merchandizing
3103.3.5 Membrane structures
503.1.1 Special industrial occupancies: All
buildings and structures designed to house low-
hazard industrial processes that require large
areas and unusual heights to accommodate
craneways or special machinery and equipment,
including, among others, rolling mills, structural
metal fabrication shops and foundries, or the
production and distribution o
area limitations of Table 503.
503.1.2 Open parking structures: Open pa
limitations specified in 780 CMR 406.4.
780 CMR: STATE BOARD OF BUILDING REGULATIONS AND STANDARDS
THE MASSACHUSETTS STATE BUILDING CODE
114 780 CMR - Sixth Edition 1/19/01
of 780 CMR applicable to the
aggregate building shall be applicable to each
building.
503.1.3 Buildings on same lot: Two or more
buildings on the same lot shall be regulated as
separate buildings or shall be considered as
portions of one building if the height of each
building and the aggregate area of all buildings
are within the limitations of Table 503 as
modified by 780 CMR 504.0 and 506.0. The
provisions
780 CMR: STATE BOARD OF BUILDING REGULATIONS AND STANDARDS
GENERAL BUILDING LIMITATIONS
1/19/01 780 CMR - Sixth Edition 115
Table 503 HEIGHT AND AREA LIMITATIONS OF BUILDINGS Height limitations of buildings (shown in upper figure as stories and feet above grade plane), and area
limitations of one- or two-story buildings facing on one street or public space not less than 30 feet wide
(shown in lower figure as area in square feet per floor ). See Note a.
n
n
Table notes appear immediately following table. N.P. = Not Permitted; N.L. = Not
Limited
Type of Construction
Noncombustible
Noncombustible/
Combustible Combustible
Type 1 Type 2 Type 3 Type 4 Type 5
USE GROUPS
Protected
Note b Protected
Unpro-
tected
Pro-
tected
Unpro-
tected
Heavy
timber
Pro-
tected
Unpro-
tected
Note a 1A 1B 2A 2B 2C 3A 3B 4 5A 5B
A-1 Assembly; theaters
N.L.
N.L.
5 St. 65'
19,950
3 St. 40'
13,125
2 St. 30'
8,400
3 St. 40'
11,550
2 St. 30'
8,400
3 St. 40'
12,600
1 St. 20'
8,925
1 St. 20'
4,200 A-2 Assembly; night clubs and
imilar uses s N.L.
N.L.
7,200
3 St. 40'
5,700
2 St. 30'
3,750
1 St. 20'
2,400
2 St. 30'
3,300
1 St. 20'
2,400
2 St. 30'
3,600
1 St. 20'
2,550
1 St. 20'
1,200
A-3 Assembly; lecture halls, recre-
ation centers, terminals, restaurants
ther than night clubs o
N.L.
N.L.
5 St. 65'
19,950
3 St. 40'
13,125
2 St. 30'
8,400
3 St. 40'
11,550
2 St. 30'
8,400
3 St. 40'
12,600
1 St. 20'
8,925
1 St. 20'
4,200
A-4 Assembly; churches
Note c
N.L.
N.L.
5 St. 65'
34,200
3 St. 40'
22,500
2 St. 30'
14,400
3 St. 40'
19,800
2 St. 30'
14,400
3 St. 40'
21,600
1 St. 20'
15,300
1 St. 20'
7,200
B Business
N.L.
N.L.
7 St. 85'
34,200
5 St. 65'
22,500
3 St. 40'
14,400
4 St. 50'
19,800
3 St. 40'
14,400
5 St. 65'
21,600
3 St. 40'
15,300
2 St. 30'
7,200
E Educational Note c N.L. N.L.
5 St. 65'
34,200
3 St. 40'
22,500
2 St. 30'
14,400
3 St. 40'
19,800
2 St. 30'
14,400
3 St. 40'
21,600
1 St. 20'
15,300
Note d
1 St. 20'
7,200
Note d
F-1 Factory and industrial
Moderate
N.L.
N.L.
6 St. 75'
22,800
4 St. 50'
15,000
2 St. 30'
9,600
3 St. 40'
13,200
2 St. 30'
9,600
4 St. 50'
14,400
2 St. 30'
10,200
1 St. 20'
4,800
F-2 Factory and Industrial
low Note h
N.L.
N.L.
7 St. 85'
34,200
5 St. 65'
22,500
3 St. 40'
14,400
4 St. 50'
19,800
3 St. 40'
14,400
5 St. 65'
21,600
3 St. 40'
15,300
2 St. 30'
7.200 H-1 High hazard,
detonaton hazards Notes e, i, k, l
1 St,20'
16.800
1 St. 20'
14,400
1 St. 20'
11,400
1 St. 20'
7,500
1 St. 20'
4,800
1 St. 20'
6,600
1 St. 20'
4,800
1 St. 20'
7,200
1 St. 20'
5,100
N.P. H-2 High Hazard
deflagration hazards Note e,i,j,l
5 St. 65'
16,800
3 St. 40'
14,400
3 St. 40'
11,400
2 St. 30'
7,500
1 St. 20'
4,800
2 St. 30'
6,600
1 St. 20'
4,800
2 St. 30'
7,200
1 St. 20'
5,100 N.P.
H-3 High Hazard
physical hazards Note e,l
7 St. 85'
33,600
7 St. 85'
28,800
6 St. 75'
22,800
4 St. 50'
15,000
2 St. 30'
9,600
3 St. 40'
13,200
2 St. 30'
9,600
4 St. 50'
14,400
2 St. 30'
10,200
1 St. 20'
4,800
H-4 High Hazard
health hazards Note e,l
7 St. 85'
N.L.
7 St. 85'
N.L.
7 St. 85'
34,200
5 St. 65'
22,500
3 St. 40'
14,400
4 St. 50'
19,800
3 St. 40'
14,400
5 St. 65'
21,600
3 St. 40'
15,300
2 St. 30'
7,200
I-1 Institutional, residential care N.L. N.L.
9 St.100'
19,950
4 St. 50'
13,125
3 St. 40'
8,200
4 St. 50'
11,550
3 St. 40'
8,400
4 St.50'
12,600
3 St. 40'
8,925
2 St. 35'
4,200 I-2 Institutional, incapacitated
Note m N.L. N.L.
4 St. 50'
17,100
2 St. 30'
11,250
1 St. 20'
7,200
1 St. 20'
9,900 N.P.
1 St. 20'
10,800
1 St. 20'
7,650 N.P.
I-3 Institutional, restrained
N.L.
N.L.
4 St. 50'
14,250
2 St. 30'
9,375
1 St. 20'
6,000
2 St. 30'
8,250
1 St. 20'
6,000
2 St. 30'
9,000
1 St. 20'
6,375
N.P.
M Mercantile
N.L.
N.L.
6 St. 75'
22,800
4 St. 50'
15,000
2 St. 30'
9,600
3 St. 40'
13,200
2 St. 30'
9,600
4 St. 50'
14,400
2 St. 30'
10,200
1 St. 20'
4,800
R-1 Residential, hotels N.L. N.L.
9 St.100'
22,800
4 St. 50'
15,000
3 St. 40'
9,600
4 St. 50'
13,200
3 St. 40'
9,600
4 St. 50'
14,400
3 St. 40'
10,200
2 St. 35'
4,800
R-2 Residential, multi-family N.L. N.L.
9 St.100'
22,800
4 St. 50'
15,000
Note f
3 St. 40'
9,600
4 St. 50'
13,200
Note f
3 St. 40'
9,600
4 St. 50'
14,400
3 St. 40'
10,200
2 St. 35'
4,800
R-3 Residential,
multiple single family
N.L.
N.L.
4 St. 50'
22,800
4 St. 50'
15,000
3 St. 40'
9,600
4 St. 50'
13,200
3 St. 40'
9,600
4 St. 50'
14,400
3 St. 40'
10,200
2 St. 35'
4,800
S-1 Storage, moderate
N.L.
N.L.
5 St. 65'
19,950
4 St. 50'
13,125
2 St. 30'
8,400
3 St. 40'
11,550
2 St. 30'
8,400
4 St. 50'
12,600
2 St. 30'
8,925
1 St. 20'
4,200 S-2 Storage, low Note g N.L. N.L.
7 St. 85'
5 St. 65'
3 St. 40'
4 St. 50'
3 St. 40'
5 St. 65'
3 St. 40'
2 St. 30'
780 CMR: STATE BOARD OF BUILDING REGULATIONS AND STANDARDS
THE MASSACHUSETTS STATE BUILDING CODE
116 780 CMR - Sixth Edition 1/19/01
34,200 22,500 14,400 19,800 14,400 21,600 15,300 7,200
U Utility, miscellaneous
N.L.
N.L.
Notes applicable to Table 503:
Note a. See the following sections for general exceptions to Table 503:
780 CMR 504.2 Allowable height increase due to automatic sprinkler system installation.
780 CMR 506.2 Allowable area increase due to street frontage.
780 CMR 506.3 Allowable area increase due to automatic fire suppression system installation.
780 CMR 506.4 Allowable area reduction for multi-story buildings.
780 CMR 507.0 Unlimited area one-story buildings.
Note b. Buildings of Type 1 construction permitted to be of unlimited tabular heights and areas are not
subject to special requirements that allow increased heights and areas for other types of construction (see
780 CMR 503.1.4).
Note c. For height exceptions for auditoriums in occupancies in Use Groups A-4 and E, see 780 CMR
504.3.
Note d. For height exceptions for day care centers in buildings of Type 5 construction, see 780 CMR
504.4.
Note e. For exceptions to height and area limitations of buildings for Use Group H, see 780 CMR 4
governing the specific use groups.
Note f. For exceptions to height of buildings for Use Group R-2 of Types 2B and 3A construction, see
780 CMR 504.6 and 504.7.
Note g. For height and area exceptions for open parking structures, see 780 CMR 406.0.
Note h. For exceptions to height and area limitations for special industrial occupancies, see 780 CMR
503.1.1.
Note i. Occupancies in Use Groups H-1 and H-2 shall not be permitted below grade.
Note j. Rooms and areas of Use group H-2 containing pyrophoric materials shall not be permitted in
buildings of Type 3, 4, or 5 construction.
Note k. Occupancies in Use Group H-1 are required to be detached one-story buildings (see 780 CMR
707.1.1).
Note l. For exceptions to height for buildings with occupancies in Use Group H, see 780 CMR 504.5
Note m. Hospitals, other than college or school infirmaries, shall be constructed of Type 1-B or
higher construction.
Note n. 1 foot = 304.8 mm; 1 square foot = 0.093 m2
503.1.4 Type 1 construction: Buildings of
Type 1 construction which are permitted to be of
unlimited tabular heights and areas by Table 503,
are not subject to the special requirements that
allow increased heights and areas for other types
of construction.
503.2 Area limitations: The area limitations
specified in Table 503 shall apply to the maximum
horizontally projected area of all buildings fronting
on a street or a public space not less than 30 feet
(9144 mm) in width with access from a public street.
503.3 Height limitations: The height in feet and the
number of stories above grade specified in Table
503 shall apply to all buildings and to all separate
parts of a building that are enclosed within fire walls
complying with the provisions of 780 CMR 7. A
basement shall be considered as a story above grade
where the finished surface of the floor above the
basement is more than six feet (1829 mm) above
grade plane; or more than six feet (1829 mm) above
the finished ground level for more than 50% of the
total building perimeter; or more than 12 feet (3658
mm) above the finished ground level at any point.
780 CMR 504.0 HEIGHT
MODIFICATIONS
504.1 General: The provisions of 780 CMR 504.0
shall modify the height limitations of Table 503 as
herein specified.
504.2 Automatic sprinkler systems: Where a
building is equipped throughout with an automatic
sprinkler system in accordance with 780 CMR
906.2.1, the building height limitation specified in
Table 503 shall be increased one story and 20 feet
(6096 mm). This increase shall not apply to
buildings of Types 2C, 3A, 4 and 5A construction
with an occupancy in Use Group I-2, or to buildings
with an occupancy in Use Group H-1, H-2 or H-3.
The building height limitations for buildings with an
occupancy in Use Group R specified in Table 503
shall be increased one story and 20 feet (6096mm)
where the building is equipped throughout with an
automatic sprinkler system installed in accordance
with 780 CMR 906.2.2 and the system is supervised
in accordance with 780 CMR 923.1, method 1, 2 or
780 CMR: STATE BOARD OF BUILDING REGULATIONS AND STANDARDS
GENERAL BUILDING LIMITATIONS
1/19/01 780 CMR - Sixth Edition 117
3, but not to exceed a height of four stories or 60 feet
(18288 mm).
504.3 Auditoriums: The maximum height of
auditoriums in Use Groups A-4 and E shall be 65
feet (19812 mm) in buildings of Type 2B, 3A, 4 or
5A construction and 45 feet (13716 mm) in
buildings of Type 2C, 3B or 5B construction.
504.4 Day care centers: The height limitations of
Table 503 for day care centers classified as Use
Group E, in buildings of Type 5 construction, shall
be increased one story and 20 feet (6096 mm)
provided that the total occupant load is less than 50
persons.
504.5 High-hazard use groups: Buildings and
structures with an occupancy in Use Group H that
requires unusual heights necessary to accommodate
special manufacturing processes and equipment shall
be exempt from the tabular height limitations, in
feet, of Table 503.
504.6 Type 3A construction: The height limitation
for buildings of Type 3A construction with
occupancies in Use Group R-2 shall be increased to
six stories and 75 feet (22860 mm) where the first
floor above the basement has a fireresistance rating
of not less than three hours and the floor area is
subdivided by two-hour fireresistance rated fire
walls into fire areas of not more than 3,000 square
feet (279 m²).
504.7 Type 2B construction: The height limitation
for buildings of Type 2B construction with
occupancies in Use Group R-2 shall be increased to
nine stories and 100 feet (30480 mm) where the
building is separated by not less than 50 feet (15240
mm) from any other building on the lot and from
interior lot lines, the exits are segregated in a fire
area enclosed by a two-hour fireresistance rated fire
wall and the first floor construction has a
fireresistance rating of not less than 1½ hours.
780 CMR 505.0 MEZZANINES
505.1 General: A mezzanine or mezzanines in
compliance with 780 CMR 505.0 shall be considered
a portion of the floor below. Such mezzanines shall
not contribute to the building area as regulated by
780 CMR 503.2. Such mezzanines shall not
contribute to the number of stories as regulated by
780 CMR 503.3. The area of the mezzanine shall be
included in determining the fire area.
505.2 Area limitation: The aggregate area of a
mezzanine or mezzanines within a room shall not
exceed _ of the area of that room. The enclosed
portions of rooms shall not be included in a
determination of the size of the room in which the
mezzanine is located. In determining the allowable
mezzanine area, the area of the mezzanine shall not
be included in the area of the room.
Exception: The aggregate area of mezzanines in
buildings and structures of Type 1 or 2
construction for special industrial occupancies in
accordance with 780 CMR 503.1.1 shall not
exceed _ of the area of that room.
505.3 Egress: Each occupant of a mezzanine shall
have access to at least two independent means of
egress where such spaces require two means of
egress in accordance with 780 CMR 1017.2. Where
a stairway provides a means of exit access from a
mezzanine, the maximum travel distance required by
780 CMR 1017.2 shall be measured to the bottom of
the stairway.
505.4 Openness: A mezzanine shall be open and
unobstructed to the room in which such mezzanine
is located except for walls not more than 42 inches
(1067 mrn) high, columns and posts.
Exceptions
1. Mezzanines or portions thereof are not required
to be open to the room in which the mezzanines
are located, provided that the occupant load of the
aggregate area of the enclosed space does not
exceed ten.
2. A mezzanine having two or more means of
egress is not required to be open to the room in
which the mezzanine is located, if at least one of
the means of egress provides direct access to an
exit from the mezzanine level.
780 CMR 506.0 AREA MODIFICATIONS
506.1 General: The provisions of 780 CMR 506.0
shall modify the area limitations of Table 503 as
herein specified.
506.2 Street frontage increase: Where a building or
structure has more than 25% of the building
perimeter fronting on a street or other unoccupied
space, the area limitations specified in Table 503
shall be increased 2% for each 1% of such excess
frontage. The unoccupied space shall be on the same
lot or dedicated for public use, shall not be less than
30 feet (9144 mm) in width and shall have access
from a street by a posted fire lane not less than 18
feet (5486 mm) in width.
506.3 Automatic sprinkler system: Where a
building, other than those with an occupancy in Use
780 CMR: STATE BOARD OF BUILDING REGULATIONS AND STANDARDS
THE MASSACHUSETTS STATE BUILDING CODE
118 780 CMR - Sixth Edition 1/19/01
Group H-l, H-2 or H-3, is equipped throughout with
an automatic sprinkler system installed in
accordance with 780 CMR 906.2.1, the area
limitation specified in Table 503 shall be increased
200% for one-and two-story buildings and 100%
for buildings more than two stories in height.
506.4 Multistory buildings: The area limitations
for buildings two stories in height shall be the same
as the area limitations provided in Table 503 for
one-story buildings. In buildings over two stories in
height, the area limitations of Table 503 for one-
story buildings shall be reduced as specified in Table
506.4.
780 CMR: STATE BOARD OF BUILDING REGULATIONS AND STANDARDS
GENERAL BUILDING LIMITATIONS
1/19/01 780 CMR - Sixth Edition 119
Table 506.4
REDUCTION OF AREA LIMITATIONS
Type of Construction
Number of
stories
1A & 1B
2A
2B, 2C, 3A, 3B, 4, 5A,
5B
1
2
None
None
None
None
None
None
3
4
None
None
5%
10%
20%
20%
5
6
None
None
15%
20%
30%
40%
7
8
None
None
25%
30%
50%
60%
9
10
None
None
35%
40%
70%
80%
780 CMR 507.0 UNLIMITED AREAS
507.1 One-story buildings: For all occupancies
other than Use Groups A-l, A-2, A-4, A-5, E, H, I-l,
I-3 and R, the area of buildings that do not exceed
one story and 85 feet (25908 mm) in height, other
than buildings of Type 5 construction, shall not be
limited, provided that the building is equipped
throughout with an automatic sprinkler system in
accordance with 780 CMR 906.2.1; and the building
is isolated as specified in 780 CMR 507.2. Buildings
with an occupancy in Use Group I-2 shall not be
constructed of Type 3B construction. Except as
modified by 780 CMR 9, fire areas of Use Group E
are permitted in unlimited area buildings in
accordance with 780 CMR 507.1.1. Except as
modified by 780 CMR 9, fire areas of Use Groups
H-2, H-3 and H-4 are permitted in unlimited area
buildings in accordance with 780 CMR 507.1.2.
Bulk Merchandising Retail Buildings designed,
constructed and operated in accordance with 780
CMR 426.0 shall be permitted to be constructed of
unlimited area.”
Exceptions:
1. Buildings and structures of special industrial
occupancies in accordance with 780 CMR 503.1.1
shall be exempt from the above height limitations
and fire separation distance requirements, and the
automatic fire suppression system shall not be
provided where such installations will be
detrimental or dangerous to the specific
occupancy as approved by the code official.
Where located with a fire separation distance of
less than 30 feet (9144 mm), the exterior walls of
such buildings shall be protected or constructed to
provide a fireresistance rating of not less than two
hours.
2. An automatic fire suppression system shall not
be required for buildings of Type 2 or Type 4
construction which are occupied exclusively for
the storage of noncombustible materials that are
not packed or crated in combustible materials.
3. Buildings and structures of Types 1 and 2
construction for rack storage facilities which do
not have access by the public shall not be limited
in height provided that such buildings conform to
the requirements of 780 CMR 507.1 and NFiPA
231 C listed in Appendix A.
4. The automatic sprinkler system shall not be
required in areas occupied for indoor participant
sports, such as tennis, skating, swimming and
equestrian activities, in occupancies in Use Group
A-3 provided that:
4.1. Exit doors directly to the outside are
provided for all occupants of the participant
sport areas; and
4.2. The building is equipped with a fire
protective signaling system with manual fire
alarm boxes installed in accordance with
780 CMR 917.0.
507.1.1 School buildings: For occupancies in Use
Group E, one-story buildings of Type 2, 3A or 4
construction shall not be limited in area where a
direct exit to the outside of the building is
provided from each classroom and the building is
equipped throughout with an automatic sprinkler
system in accordance with 780 CMR 906.2.1.
Exterior walls on all sides of such buildings shall
comply with 780 CMR 507.2.
507.1.2 High-hazard use groups: Use Group H-
2, H-3 and H-4 fire areas shall be permitted in
occupancies in Use Groups F and S except as
modified by 780 CMR 9, and in lecture halls and
laboratories in Use Groups A-3, B, E and I-2 in
accordance with the limitations of 780 CMR
507.1. Fire areas located at the perimeter of the
building shall not exceed the area limitations
specified in Table 503 as modified by 780 CMR
506.2, based upon the percentage of the perimeter
of the fire area that fronts on a street or other
unoccupied space. Interior fire areas shall not
exceed 25% of the area limitations specified in
Table 503. Fireresistance rating requirements of
fire separation assemblies shall be in accordance
with Table 313.1.2.
507.2 Exterior walls: The minimum fireresistance
rating of exterior walls of one-story buildings of
unlimited area shall be determined by the use group
and the fire separation distance as specified in Table
507.2, but shall not be less than the fireresistance
rating required by Table 602 for the type of
construction. The entire perimeter of one-story
780 CMR: STATE BOARD OF BUILDING REGULATIONS AND STANDARDS
THE MASSACHUSETTS STATE BUILDING CODE
120 780 CMR - Sixth Edition 1/19/01
unlimited area buildings shall have a minimum fire separation distance of 30 feet (9144 mm).
Exception: The minimum fire separation
distance of 30 feet (9144 mm) shall not apply to a
wall facing another building on the same lot,
provided that:
780 CMR: STATE BOARD OF BUILDING REGULATIONS AND STANDARDS
GENERAL BUILDING LIMITATIONS
1/19/01 780 CMR - Sixth Edition 121
1. Such wall is constructed as a fire wall in
accordance with 780 CMR 707.0;
2. The length of the fire wall does not exceed
25% of the total perimeter of the unlimited area
building;
3. The adjacent building has a minimum fire
separation distance of 30 feet (9144 mm) on
all sides, except for the side that faces the
unlimited area building; and
4. The adjacent building is equipped
throughout with an automatic sprinkler system
in accordance with 780 CMR 906.2.1.
507.2.1 Opening protective: Openings in
exterior walls required by Table 507.2 to have a
fire resistance rating of three hours or more shall
be protected with fire assemblies having a fire
resistance rating of not less than three hours.
Openings in exterior walls required by Table
507.2 to have a fire resistance rating of two hours
shall be protected with fire assemblies having a
fire protection rating of not less than 1½ hours.
Table 507.2
MINIMUM FIRE RESISTANCE RATING
OF EXTERIOR WALLS
Fireresistance rating (hours) based on
fire separation distancea
Use Group
30 Feet or greater but
less than 50 feet
50 feet or
greater
E
A-3, B, F-2, I-2, S-2
F-1, M, S-1
1½
2
3
0
0
0
Note a. 1 foot = 304.8 mm.