Building Design and Construction Handbook - Merritt - Ventech!

WALL, FLOOR, AND CEILING SYSTEMS 11.23
Bearing Walls. These should be at least 12 in thick for the uppermost 35 ft of
their height. Thickness should be increased 4 in for each successive 35 ft or fraction
of this distance measured downward from the top of the wall. Rough or random or
coursed rubble stone walls should be 4 in thicker than this, but in no case less than
16 in thick. However, for other than rubble stone walls, the following exceptions
apply to masonry bearing walls:
Stiffened Walls. Where solid masonry bearing walls are stiffened at distances not
greater than 12 ft by masonry cross walls or by reinforced-concrete floors, they
may be made 12 in thick for the uppermost 70 ft but should be increased 4 in in
thickness for each successive 70 ft or fraction of that distance.
Top-Story Walls. The top-story bearing wall of a building not over 35 ft high may
be made 8 in thick. But this wall should be no more than 12 ft high and should
not be subjected to lateral thrust from the roof construction.
Residential Walls. In dwellings up to three stories high, walls may be 8 in thick
(if not more than 35 ft high), if not subjected to lateral thrust from the roof construction.
Such walls in one-story houses and one-story private garages may be 6
in thick, if the height is 9 ft or less or if the height to the peak of a gable does not
exceed 15 ft.
Penthouses and Roof Structures. Masonry walls up to 12 ft high above roof level,
enclosing stairways, machinery rooms, shafts, or penthouses, may be made 8 in
thick. They need not be included in determining the height for meeting thickness
requirements for the wall below.
Plain Concrete and Grouted Brick Walls. Such walls may be 2 in less in thickness
than the minimum basic requirements, but in general not less than 8 in—and
not less than 6 in in one-story dwellings and garages.
Hollow Walls. Cavity or masonry bonded hollow walls should not be more than
35 ft high. In particular, 10-in cavity walls should be limited to 25 ft in height,
above supports. The facing and backing of cavity walls should be at least 4 in thick,
and the cavity should not be less than 2 in or more than 3 in wide.
Faced Walls. Neither the height of faced (composite) walls nor the distance between
lateral supports should exceed that prescribed for masonry of either of the
types forming the facing and the backing. Actual (not nominal) thickness of material
used for facings should not be less than 2 in and in no case less than one-eighth
the height of the unit.
Nonbearing Walls. In general, parapet walls should be at least 8 in thick and the
height should not exceed 3 times the thickness. The thickness may be less than 8
in, however, if the parapet is reinforced to withstand safely earthquake and wind
forces to which it may be subjected.
Nonbearing exterior masonry walls may be 4 in less in thickness than the minimum
for bearing walls. However, the thickness should not be less than 8 in except
that where 6-in bearing walls are permitted, 6-in nonbearing walls can be used also.
Nonbearing masonry partitions should be supported laterally at distances of not
more than 36 times the actual thickness of the partition, including plaster. If lateral
support depends on a ceiling, floor, or roof, the top of the partition should have
adequate anchorage to transmit the forces. This anchorage may be accomplished