FLOOR." [This specification is given as a guide in preparing specifications for this and similar floors. Most of the various fireproofing companies have printed specifications for their systems, which they furnish to architects on application.]
The floor construction to be used in this building shall be that known as the "Roebling System," consisting of a steel-ribbed wire cloth and concrete arch with ceilings suspended below the level of the floor beams. A continuous air space between the floor and ceiling and around the girders shall be provided.
The wire centring for the floors shall consist of No. 19, four-warp two-filling wire cloth stiffened with 3/8 to ½-inch steel rods woven into the cloth at intervals of about 9 inches. This centring shall be sprung in between the I-beams in the form of an arch with the ends of the rods abutting against the beams. The sheets to be well lapped and securely laced. Over the crown of this centring one or more 5/16-inch steel rods shall be laced parallel to the beams to secure proper longitudinal bracing.
In all spans over 3 feet 6 inches a heavy galvanized wire shall be dropped down from the stiffening rib of the arch at intervals of not over 3 feet to support the ceiling.
Over the wire arch so constructed cinder concrete mixed in the proportions of 1 part of high-grade Portland cement to 2 parts of sharp sand and 5 parts of clean cinder shall be laid to a sufficient thickness to secure the required strength, as designated elsewhere in these specifications. The concrete generally to be leveled (2 inches above) the top of the floor beams where wood floors are specified, and to the specified levels where other than wood floors are designated.
The floors to be subject to test at any point that may be designated by the architect, and at any time after the concrete is fifteen days old. The floor shall in all cases develop a strength of 1,000 pounds per square foot when the load is concentrated, and similarly a strength of 600 pounds per square foot when the load is uniformly distributed over one-half of the span.