REPOKT OF UNDERWRITERS' COMMITTEE. 65 
In addition to the frame, ordinary joisted brick, so-called fireproof, 
and mill buildings, there were in San Francisco four buildings of a 
monumental type, so far as weight of construction was concerned. 
These were the new city hall (PI. XXXI), the new post-office build- 
ing (Pis. XLIII and XLIV), the United States mint (PL 
XXXVIII), and the appraisers' stores, or custom-house (PL 
XXVIII, A). The few mill buildings which existed were not of a 
standard type, according to the report of the National Board of 
Fire Underwriters. The fireproof buildings had been erected in 
accordance with the building laws of San Francisco, which provided 
for three principal types of commercial buildings, known as class A, 
class B, and class C. 
The general requirements for buildings of these classes and for mill 
buildings are as follows: 
BUILDINGS IN FIRE LIMITS. 
Section 96. Every building hereafter erected within the fire limits shall be 
constructed in accordance with the requirements of this ordinance for the con- 
struction of buildings of either class A, class B, or class C. 
buildings of classes a, b, and c. 
Section 97. Class A, termed " fireproof," or " skeleton construction," shall 
include all buildings wherein all external and internal loads and strains are 
transmitted from the top of the building to the foundation by skeleton or frame- 
work of steel, and the beams or girders of which are riveted to each other at 
their respective juncture joints. A building of this class must be constructed 
of noninflammable material throughout, and all interior constructive metal 
work, with the exception of the framing for elevators and staircases, shall be 
protected from fire by brick or terra cotta at least li inches thick, or by plas- 
tering three-fourths of an inch thick applied to metal lath. The face of the 
plastering shall be U inches from the metal. Wood may be used only for 
window and door frames, sashes, standing finish, hand rails for stairs, and for 
the upper and under floors and their necessary sleepers. Wood may also be 
used for isolated furring blocks, but this class shall not permit the use of laths 
or furrings of wood. 
Class B. A building of this class shall be constructed with all its exterior 
walls and piers of masonry, or of masonry and steel, and all exterior surfaces 
other than masonry shall be covered with noninflammable materials. All par- 
titions, furred walls, or other plastered surfaces throughout shall be metal 
lathed. All interior metal work shall bo protected as in class A, and in addition 
the floor and ceiling joists, posts, roof boards, and partitions may be of wood in 
such places as does not violate the requirements of any section or clause of this 
ordinance. 
Class C. A building of this class shall be constructed the same as class B in 
every respect, except as to the requirements for interior lathing. 
Section 98. Limit of height of buildings of classes A, B, and C : 
Feet. 
Class A, limit of height 220 
Class B, limit of height 100 
Class C, limit of height. 82 
(As amended by Ordinance 1297.) 
