FIREPROOF CONSTRUCTION

FIREPROOF CONSTRUCTION

Does it Afford Added Fire Protection?

Perez M. Stewart,

Superintendent

Department of Buildings, Borough of Manhattan. New York City.

In a paper on fireproof construction read at Detroit, Mich., last month before the convention of the International Association of Fire Engineers, by Perez M. Stewart, late superintendent of buildings in the borough of Manhattan, New York, the efficiency of such buildings was assumed as a fact. He divided fire protection as follows: (1) Protection from without afforded by the municipality; (,2) by the construction of the building itself, enabling it to withstand the effects of fire from within or without; (3) by the fire-detecting and firefighting devices installed in, but not integrally a part of the building itself. The first kind needed no words from him; the third, if treated of, would be so technical as to be familiar only to a specialist. In speaking of the second division of the subject he recognised the good work done, or to be done by the New England Mutual Fire Insurance companies; the laboratory and testing station of the National Fire Prevention association of Chicago; the four-year course in fire protection at the Armour Institute in the same city; and the testing station of the British Fire Protection committee. The need of fireproof buildings was then considered, especially since so many hotels, theatres, and department stores are putting up such large structures. The department store, in particular, is a source of danger, owing to its large ground area, extended to considerable height and connected in this height by what is usually known as the light well—to say nothing of the nature of the goods sold and stored in them. In its case, probably three to five times as many people are allowed to congregate, to the square feet of building occupied, without adequate provision being made for their safety, and this especially during the holiday season, when every possible extravagance of decoration is practised by the management, without considering the fire hazard. An instance of this was the snowstorm in the light well of one such store, which was composed of thousands upon thousands of bits of cotton suspended at different altitudes. To reduce the fire hazard in buildings, therefore, there are three requisites: (1) The use of incombustible and firperoof material; (2) the manner of combining the materials of construction ; (.3) the provision of devices and forms of construction that afford protection against fire from the outside. 1—As to incombustible materials—such as not only do not burn, but remain intact under the action of fire, and preserve their strength or the strength of those parts which they protect: These as a rule are brick, stone, terra cotta, wire-glass, iron, steel, and concrete—which, though not all of themselves fireproof, will not burn or produce flame, when subjected to a heat of from 2000° to 3000° Fahr. The new clinic of St. Bartholomew’s parish. Manhattan, was quoted as an excellent example of fireproofing. Except in the offices of the trustees, whose self-indulgent spirit was yielded to to the extent of being allowed hardwood furniture and a soft floor rug, the whole of the furnishing throughout the building is of incombustible material. The unprotected iron column was especially condemned. Cast iron, of course, will not burn, but under the effects of intense heat, columns of that material will bulge, collapse, and come down with a run, endangering life and property. The McMahon cracker factory, in Chicago, was quoted. One-half was of slow-burning construction, con sisting of columns, girders, and floors of yellow pine. At one end was a bakery, with brick walls and concrete-protected steel beams and columns. The fire completely destroyed the slow-burning portion of the building, and generated an intense heat, notwithstanding which the bakery referred to. abutting upon it. weighing, with its ovens, nearly 1.000 tons, remained in position at the end of the fire, columns and all, at its original height, extending from the third to the fourth stories. The manner of construction. or the disposition and arrangement of parts of construction are even more important than the use of incombustible materials. To a certain extent it may justly be claimed that, with the proper use of combustible materials (practically wood) for the interior work of buildings a structure can be made as safe against the spread of fire, as if built of incombustible materials. When wood is used, and is exposed, as little surface as possible should be exposed. With only one side of the material to work on and a necessarily limited supply of air. the flames will spread less rapidly. But care should be taken to select hard woods, such as oak and yellow pine (the best structural materials among woods), which are more difficult to burn and sustain the flames less readily. Ordinarily paints and especially varnishes should be avoided As the danger of a fire spreading increases (1) with the increase in area covered by the buildings, and (2) in greater degree, with the increase in height, fire-stops in the way of brick walls or fireproof partitions should be provided, with only fireproof doors or windows for openings. The spread of fire vertically is most effectively guarded against by making the floors continuous and unbroken. by having no openings in them, and placing stairways, elevators, pipes, shafts, belts, etc., in shafts entirely separated from the rest of the building by brick walls. Attention to this detail is most important. In one of New York’s early fireproof office buildings there occurred a fire some years ago, in which the greatest damage was done in an office two stories above the one in which the fire originated. The flames in the lower story burned away the woodwork casing round the smoke or drain pipes, and were drawn up through the openings in the floor for the pipes, and, in this way, ascended to the upper story, where they destroyed the pipe casing and set fire to the contents of the room. This fire also showed the danger of furring and casing, especially of wood. Air-spaces are thus formed which constitute channels, through which fire, by creating draught in them, is spread. All casings, wainscoting, trim, etc., should be solidly backed up with some incombustible material; or, in case it is impracticable so to back them up, good and sufficient fire-stops, at least, should be provided at intervals. In nonfireproof buildings, where wood floors or stud partitions are used, a judicious use of fire-stops is very desirable. In the spaces formed by wood floor beams, the floor and ceiling act as a flue, through which the fire spreads very rapidly; so do the spaces between the treads in the soffits of stairs. In the case of wooden starirways, it is very desirable that fire stops of some incombustible material should be provided. Steam coal ashes or similar incombustible materials placed flush with the floor beams make not only an excellent fire-stop by protecting the floors to a great extent, but serve the additional purpose of deafening or preventing the transmission of sound. In fire proof floors where wood flooring is used secured to wooden sleepers, it is very important that the space between the sleepers up to the underside of the flooring be filled in solidly with some incombustible material. An elevator shaft forms a flue which draws the flames up with great force. It should, therefore, be absolutely fireproof and of incombustible materials. The department of buildings of New York city requires that the proposed construction shall practically remain intact, after having been exposed to a fire maintained for one hour at a tent perature of 1700° Fahr., and then subjected to a stream of water at thirty pounds pressure for five minutes. Any construction used should be self supporting, and the ironwork thoroughly protected by some fireproof covering. No woodwork should enter into its construction, and fireproof doors should be provided for every opening—the fire underwriters’door, even although not fair to look upon, is the best type of doors for all purposes. If that is not used, doors and frames of metal or wood covered with metal (the “Kalimincd” process) should be employed. In shafts only door openings should be allowed. If light is needed, and windows opening directly to the outer air are impossible, window lights should be used in the doors, or. if that is not sufficient, sta tionary metal sashes set in metal frames should be employed; but in every case wire-glass should be made use of. Light and vent shafts, being as dangerous as elevator shafts, should come under the same rides, except, of course, that the window sashes cannot be made stationary. Pipe shafts should be solid for their full length, with provision made for expansion and extraction. The openings for service pipes at each store can thus be completely filled up by the pipes, without danger to pipe or partition. There is always risk of fire damage from outside exposure. The best protection against this is a brick wall increasing in thickness from the top down. As space is so valuable, a building cannot be rendered practically safe against fire from the outside by inclosing it on all sides in solid walls carried three feet above the roof. The exposure hazard is responsible for nearly one-third of the entire fire loss of the country. In almost every case, fire is communicated from one building to another through wall openings—through doors or windows—and, to provide against this danger, fire-protectionists have devoted some of their best endeavors. Wall openings must normally be more or less open to traffic or the passage of light, and practical experience has shown that any considerable amount of heat warped the sheet iron shutter so greatly as to make it useless Hence, arose the tin-covered wooden shutter—a device without a superior for many forms of wall opening protection, but open to several objections, of which two are serious Such a shutter does not allow of a night fire being seen from the outside; it does not lend itself easily to the adoption of devices to close the shutter automatically in case of fire; and it is very unsightly. Wire-glass eliminates these defects, and is, besides, possessed of many added advantages. A window glazed with it should be set in a sash and window frame covered with metal, or should have a hollow metal sash. Wire-glass is made either with an opaque or polished surface, and the wire reinforcing, imbedded in the glass itself, although keeping the window intact against the attack of a fire of almost any intensity, may be broken readily by the firemen, when it becomes necessary to enter the building or introduce a fire stream. In many recent important fires the efficiency of wire glass windows in reducing the exposure hazard was shown. The spread of fire to very valuable properties standing but a few yards distant was prevented through the resistance offered by the wire-glass windows in the adjoining building. The walls of buildings, wherever practicable, should extend two or three feet above the roof level. This is absolutely essential in the case of parapet walls, or walls adjacent to other buildings, to prevent the creeping of fire along the roofs. Roof coverings must always be of some fireproof material, such as tin, iron, slate, or tile, and, where openings exist, a filling of wire-glass skylights. These materials best resist the passage of heat from falling embers, or flames lapping over the parapet walls. The tile and slate are slower in transmitting heat than the iron or tin, and for this reason, perhaps, afford a better protection. A careful application of the above general principles will undoubtedly reduce the fire hazard and give added protection, as facts obtained from actual fires prove. Fires will occur even in fireproof buildings, as it is impossible to eliminate combustible materials alto gether. But experience shows that fires originating in fireproof buildings have often been positively confined to the lofts or rooms in which they started, and in which the buildings themselves suffered no fur ther injury than a discoloration of the paint, breaking of the window glass, etc. In New York beyond any other American municipality the subject of fireproof construction has been given the most painstaking study, and the results achieved have more than justi fied the labor.

FIREPROOF CONSTRUCTION.

FIREPROOF CONSTRUCTION.

How far does fireproof construction stand the test of a fierce blaze? The question is often asked, and, as yet, no sure answer has been returned in the face of the many instances, especially in Pittsburgh and Detroit, where it seems to have proved a failure. The building shown in the accompanying illustration (reproduced by courtesy of the Insurance Press of New York) shows the ruins of a large cracker factory in a Western city after the building had been subjected to a fiery trial. The structure was four stories in height, with a basement of heavy mill construction, with the exception of the mortar under the ovens. These are of brick, fireproof construction, five in number, of brick, thirty feet high, with an area of ten by twenty feet. Their bases are at the fourth floor line; they extend through the fourth and fifth stories to the roof; and. with their framework and machinery their weight is about 200 tons each. Steel columns support them; these are three stories and basement (fifty feet) high. and have heavy steel girders at their top, on which the oven walls are built. According to our informant, the “fire had gained such headway when discovered that it was impossible to check it. The heavy trussed roof fell in; the upper three stories of the south brick wall fell outwards, and all the floors were destroyed, leaving the ovens and north wall standing. The columns and girders supporting the ovens were protected with cinder concrete, made of one part natural rock cement and four parts soft coal cinders, which fireproofing was three inches deep at the nearest approach of the metal to the air. This concrete was covered with metal lath and plastered over its entire surface with a heavy finishing coat of cement mortar.” As can be seen in the illustration, the columns are still carrying their heavy loads, and their concrete fireproofing is as good as new and unbroken, except where floor beams entered, and where the wood floor construction was supported by the steel columns at the several floor lines.

FIRE-PROOF FACTORY AFTER FIRE.

It may be added that the whole exterior of this building was of yellow pine, except where has been already noted. The fire was, consequently, a very hot one. This construction came into direct contact with the covering of columns and girders even entered it, as explained; yet the entire interior of the building was burned away, leaving the 1,000 tons of brick masonry standing high in the air. In this case at least the object lesson showed that these fireproof construction is not altogether a fiction.