SAFEGUARDING THE VERTICAL HAZARD

SAFEGUARDING THE VERTICAL HAZARD

In an article that appears in the current Quarterly of the National Fire-Protection association, the editor, Henry A. Fiske, deals with the subject of fireproof buildings, lie points out that, while some of these will remain structurally intact, even when subjected to a severe conflagration, others, owing to faulty construction or design, may not only sustain greater damage than a “standard” fireproof building, but, also, will be of less service as fire-stops in case of exposure or conflagration-fires. In many such cases the fire spreads from floor to floor and the damage done by these local or internal fires is much greater than it ought to be. “1 1ms we have fires spreading from one floor to another because of unprotected floor openings, pipe-holes, etc. We have the steel work exposed to heat, with possible buckling due to poor insulation or improperly secured. We have floor-arches giving way on account of faulty construction or material, all of which simply emphasises the fact that a ‘fireproof’ building to be worthy of its name must be properly constructed in all its details.” The rules of the National Board should be followed, and these stand for “proper workmanship as well as proper design, and the former, at least, will seldom be obtained without proper supervision. Perhaps, the best, if not the only way to obtain this supervision, is by frequent inspection by those familiar with buildings of this class who can detect poor workmanship or weakness in the construction details. It is evident that inspection by a disinterested party should be of much value, and in some localities the insurance or local board inspector follows more or less closely the erection of fireproof buildings sometimes to great advantage of the property owner, who naturally desires to have good workmanship and to avoid all defects.” Such an inspector should not be so much a critic of the general design of the building as one who is familiar with many of the details. I he results of such inspection are good, as by its means are detected the more common defects namely, holes in floors for piping or conduits, breaking of the insulation and leaving openings sufficiently large for tire to spread from one floor to another or water to run through; faulty insulation improperly fastened; partitions weak and not secured to ceiling; incomplete insulation of columns or girders, etc., etc. These remarks introduce some suggestions by Henry V. Thayer, acting superintendent of the Boston Board of Fire Underwriters. Among these is one to the effect that such inspection should be most diligent while the work of construction is going on. lie should be “well versed in the different methods of construction and able to judge as to the quality of workmanship and materials used. * * * The questions of the ar rangement and method of constructing floors and supporting members and the factor of safety may be left to the architect and engineer, subject, of course, to the building laws governing in the place where the building is located.” He should note the following: The style of foundation piles, concrete, stone masonry or grillage. I he walls If skeleton, their thickness on each story and manner of support on frame; if cage, the thickness and tieing to frame; if carrying floors, the thickness and anchoring of beam, rhe columns Steel or cast iron and construction of each. If exterior, of what kind is the insulation. brick, terra-cotta, concrete or metal. Lath, its thickness and how applied. If interior, in addition to the above, note whether or not that insulation extends entirely to ceiling and masonry floor in all cases. The girders carrying exterior or interior walls, with size in inches and weight per foot. Insulation as in the case of columns. Beams—Whether (if floors are of terra-cotta) they are skew backs or half skew-backs and if beam-plates are used. If concrete floors, whether concrete haunches and metal lath on flanges, concrete slabs or moulded concrete. Floors (if of terra-cotta) The thickness of the blocks, hard, porous or semi-porous, side or end-construction ; arches, laid true and straight, with all joints well idled with cement mortar and proper size keys (not broken tile or slabs) used. Concrete floor-brand of cement and composition of mixture, character of metal reinforcement and minimum of concrete covering metal should be noted. Upper floors—Their construction, whether plank, with wearing-floor above, Ls in. double or single, with or without sleepers; if the former, note if the intervening space is filled with concrete—“preferably (says the writer) a cinder mixture”—and with no air-space under the finished floors. Partitions.—Note material of partitions, whether terra-cotta, metal lath and plaster (single or double), plaster blocks or conciete. Note thickness, and whether or not set on masonry floor. Note door and window frames in same, whether wood or iron. Finish.— Note doors, if solid wood or glazed, with or without toplights. Note hallway finish, whether wood, marble or plaster. Stairs.—Note whether open or inclosed (if inclosed, in what manner) construction, whether iron, concrete or Guasta vino tile. If of iron, note treads, whether iron, marble or slate, if marble or slate, whether or not iron webs or plates are provided under same. Elevators.Note whether open or inclosed (if inclosed, in what manner). Elevator Doors.— Note whether standard fire; metal-clad paneled, iron, wire-glass or grill. Floor Openings.—Note if any openings in floors, as for pipes, conduits, dumbwaiters or similar purposes, and how protected. Roof.—Note roof covering and pent houses—how built. Note whether any space between ceiling of top story and roof, and whether structural metal in same is insulated as required. If these details are not observed and noted by inspectors while the building is being erected, the possibility of obtaining improvements or eliminating defects during construction is of greater difficulty, for after the building .is finished the defects are almost always covered up and remain a menace to the risk. As examples of the above, may be noted the following defects which have been frequently discovered and corrected during construction: Unprotected metal in the space between ceiling of top story and roof; column-tops which are intended to be covered by ornamental capitals, and not properly insulated before these are put in place; pipeholes, which may be concealed by upper floors; broken terra-cotta tile caused by careless cutting.

As the object of every community is the elimination of the sources of fire, so one of these principal sources and one of the most neglected is the vertical, as opposed to the horizontal hazard. In planning the buildings of today the danger of the vertical openings is all but forgotten, or it is passed over unthought of or disregarded on all sides. Yet, as tested in use, other things being equal,, as is known to all practical firemen, fire spreads more rapidly vertically than horizontally, and the average modern building, as a rule, is so constructed as to afford the flames the greatest facility for an upward spread, so that (to quote from the paper of F. S. Hand read before the Dallas convention of the International Association of hire Engineers), “unless the blaze is quenched in its incipience, it has assumed such proportion at the arrival of the department that its clean sweep is certain.” While the “vertical hazard is somewhat difficult to treat in a building already erected, no excuse exists for its presence in buildings planned with the knowledge of today.” Mr Hand shows further that, in addition to the danger to the building itself, the rapid spread of fire vertically through a structure presents a serious menace to adjacent buildings. The rapidity with which fire will sweep through a building with unprotected vertical openings often causes the general outbreak of fire by generating tremendous quantities of gases and heated air. Flames will belch from every outside window in the building—making a concerted attack of heat, which will ignite other structures at a distance of 50, 60 and sometimes too ft., as at Baltimore. “The vertical fire-hazard is usually represented by uninclosed elevator shafts and stairways. The ideal remedy is ⅜ * * a brick tower erected outside the wall line of the building, with openings from the tower to the separate floors and protected by double tin-clad doors. This type of construction is not feasible in the majority of city buildings, and the next best solution is a brick shaft within the wall line having similarly protected openings [for elevator-shafts and stairways], * * * Considerations of appearance often preclude brick or other opaque elevator and stairway inclosures, and. as a substitute, we have wire-glass in metal framing. The applications of this material for the reduction of the vertical tire-hazard have been both many and interesting. From the beginning of the mechanical and physical demand which brought into being wire-glass, the possibilities for its application have been multiply ing continuously. * * * About fifteen years ago, more or less by accident, it was found that wire-glass, properly framed, filled in highest measure the function of a fire-retardant for window, door and skylight openings.” The efficiency of wire-glass as a fire-stop in wall openings was soon acknowledged, and its use was strongly recommended by the fire underwriters for the protection of all openings exposed to clanger by fire in the outside shells of well-ordered buildings, and for its utilisation as a protective agent in connection with ornamental and bronze work both within and without the building itself. It is not only fire-retardant, but, also, a complete and always available solution of the difficulty and danger attending the fall of broken glass—one to which firemen arc particularly exposed. One special and very important use for wire-glass is the inclosing of elevator-shafts. The ordinary metal grille, when backed up by this type of glass, “fills every requisite of a firestop, admits the passage of light in either direction and allows a clear view of the passage of the cars as well as of waiting passengers.” Excellent examples of this type of construction are to be found in many of the large department store and skyscraper office buildings in New York city, in which the vertical fire-hazard has thus been practically eliminated. For fireproof partitions, also, where light is an object, nothing can better suit the desired purpose. In one department store in New York city these fireproof partitions arc 8 ins. thick and built of iron, marble and plate wire-glass. “One of the important considerations in public school design is the conservation of life in times of emergency. Speaking broadly, this means protection from the dangers of fire and panic. To accomplish this successfully does not imply in every instance the erection of thoroughly fireproof buildings, but, rather, the provision of such divisional cut-offs on each floor as shall enable pupils to find a refuge where they may be free from smoke and flame. These cut-offs are best placed at stairways. The general practice obtaining in the public schools of Greater New York is along this line. * * * Main stairways have been absolutely cut off by fireproof partitions, and, where necessary, to introduce light into such openings, wire-glass has been installed.” It may also be added that till the light-well in the department stores of the future, with an area sometimes of 3.000 ft. or more, extending from the ground-floor to the roof, is forbidden by law, it should be inclosed with wireglass in metal framing, thereby minimising the hazard, without interfering with the distribution of light. The conclusions at which Mr. Hand arrives are the following: “t.—To confine fire to the floor upon which it originates it is necessary to inclose all vertical openings. 2.—The most efficient inclosure is a brick partition, with openings at each floor protected by double tin-clad doors. 3.—Where brick shafts are not possible, the best substitute is wire-glass in angle-iron raining. 4.—Outside windows in buildings having each floor cut off from the rest, should be protected with shutters or be glazed with wireglass. 5.—In view of the immense damage wrought by the vertical fire-hazard, municipal building laws everywhere should be modified to provide for its elimination.”

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