This section is from the "Architectural Iron And Steel, And Its Application In The Construction Of Buildings" book, by WM. H. Birkmire.. Also see Amazon: Architectural Iron And Steel, And Its Application In The Construction Of Buildings.
Outside fire escapes should be placed on all dwelling houses over two stories in height, occupied or intended to be occupied by two or more families on any floor above the first; on dwellings more than four stories in height, occupied by three or more families above the first floor; and on office buildings, hotels and lodging houses, factories, mills, workshops, hospitals, asylums and schools. They are constructed as follows:
Brackets should be not less than 1/2 X 1 3/4-inch wrought iron, placed edgewise, or 1 3/4-inch angle iron 1/4 inch thick, well braced, and not more than 3 feet apart, and the braces to brackets not less than 3/4-inch square wrought iron, and should extend two thirds of the width of the respective brackets or balconies. In all cases the upper bar of brackets should go through the wall and be turned down 3 inches.
Brackets On New Buildings should be set as the walls are being built. When brackets are to be put on old houses, the part going through the wall should be not less than one inch diameter, with screw nuts and washers not less than 5 inches square and 1/2 inch thick.
The top rail of balcony must be 1 3/4 X 1/2-inch wrought iron, or 1 1/2-inch angle iron 1/4 inch thick, and in all cases must go through the walls and be secured by nuts, and 4-inch-square washers at least 3/8 inch thick; and no top rail should be connected at angles by means of cast iron.
Bottom rails must be 1 1/4 X 3/8-inch wrought iron, or 1 1/2-inch angle iron 3/4 inch thick, well leaded into the wall. In frame buildings the top rails should go through the studding, and be secured on the inside by washers and nuts as above.
The filling-in bars to be not less than 1/2-inch round or square wrought iron, placed not more than 6 inches apart between centres, and well riveted to the top and bottom rails.
The stairs in all cases must be not less than 18 inches wide, and constructed of 1/4 X 3 1/2-inch wrought-iron sides or strings. Steps'may be of cast iron of the same width as strings, or 5/8-inch round iron, double rungs, and well riveted to the strings. The stairs to be secured to a bracket on top, and to rest on and be secured to a bracket or extra cross-bar at bottom. All stairs must have a 3/4-inch handrail of wrought iron, well braced.
The flooring of balconies must be of 1 1/24 X 3/8-inch wrought-iron slats placed not over 1 1/4 inches apart, and secured to iron battens, 1 1/2 X 3/8 inch, not over 3 feet apart and riveted at the intersection. The openings for stairways in all balconies should be not less than 20 inches wide and 36 inches long, and have no covers.
Drop ladders from lower balconies, where required, should be not less than 14 inches wide, and be made of 1 1/2 X 3/8-inch sides and 5/8-inch rungs of wrought iron. In no case should a drop ladder be more than 12 feet in length, nor should the ends of balconies extend more than 9 inches beyond the brackets.
The Height Of Railing around balconies should be not less than 2 feet 9 inches.
Ornamental Fire Escapes very seldom become an ornament to a building unless ornamental balconies are provided as a feature in the design. The brackets are generally made of cast iron with heavy ornamentation, or wrought iron brackets of scroll designs, and should not be placed farther apart than 3 feet, unless the floor is increased in proportion.
Fire Escapes For Schools, Factories, Etc should have the balcony extend across several windows; the stairs constructed of cast-iron treads and wrought-iron strings, and arranged outside of balconies.
This is principally used for openings into coal vault under sidewalk. The frame is set upon arches or iron beams, and placed level on top with finished sidewalk, the height at A varying with the thickness of concrete filling of sidewalk. The frame to be cast 1/2 inch thick with 3/4 of an inch rebate for the cover. The cover has a roughened surface to prevent pedestrians from slipping. It is cast 1/2 inch thick in centre to 3/4 of an inch at rebate, and made from 16 to 24 inches in diameter. Almost any size can be made for special purposes. For sidewalks made of granite only the cover is necessary, a rebate being cut in the stone.
Cast-Iron Grating for ventilating areas under sidewalk. This is from 4 to 8 inches wide by 8 to 12 inches long, with a border about 2 inches wide, and secured to stone with counter-sunk expansion bolts or screws. These gratings are galvanized, and when from 12 to 14 inches square they have a movable slat register and iron drawer to prevent the dirt from falling through.