Concealed Spaces Present Major Problem in Fire Attack

Concealed Spaces Present Major Problem in Fire Attack

Unseen, Hard-to-get-at, Fires May Tax Skills and Facilities of the Best Fire Force

Editor’s note: Behind the terse accounts of many serious fires that got away from fire fighters, runs current the incidence of hidden, or concealed spaces in which, and through which fire bred and traveled, out of reach of firemen and fire streams.

These fires offer serious problems in fire detection, attack and control, problems that may face every fire department, large and small. For the handicap of the “unseen fire” can be found in every type of building and in almost every occupancy.

Thus far, there appear to have been few attempts to study this universal problem in the light of fire attack methods and strategy. Yet the subject is one which should have paramount consideration in the fire service.

The study which follows does not attempt to review and encompass the entire subject but only the more important phases of it. The author hopes merely to direct more thinking and more study on the part of fire control strategists to the matter.

In this connection, readers are urged to review collateral texts which bear upon other related phases of fire attack, in the series of studies by the same author, entitled: “Coordinated Attack Urged to Improve Fire Control Strategy” (Fire Engineering, April, 1949); “Adequate Lighting Speeds Up and Safeguards Fire Attack” (July, 1948); “Carrying the Attack—and the Water—to the Fire” (Sept. 1949) ; “Modern respiratory Equipment Essential in Fire Attack.” (Feb., 1950).

THE hazard of the concealed breeding ground of fire is not limited to any one type of occupancy. It is found in new as well as old buildings, and very widely in rebuilt structures. The “concealed space” which plagues the fire fighter may be the result of structural failure or, as is more often the case, it may be the direct result of carelessness in design and construction.

Concealed spaces which further fire arc found not only in buildings, but in the contents of buildings. Fire can hide and spread through storages in conveyances—ships, freight cars and trucks.

It can lurk beneath piers, platforms, sidewalks and behind signs. On Sept. 11, last, fire originated in a concealed space formed by the flooring of a grandstand and the combustible ceiling of a storage room in Louisville. Caused no doubt by a cigarette that dropped through a crack in the grandstand floor, the resulting fire drove more than 5,000 persons out of the stand and caused property loss of $213,300.

Two pet biding places of fire are attics and basements. In between, there are numerous other concealed spaces—channels and pockets for fire to originate or spread. Among these may be mentioned air conditioning, ventilating and exhaust systems; piping and fittings for plumbing, heating and lighting, insulation and acoustical installations; coverings for pipe and structural supports. Then of course, there are the spaces created by partitions, falsework, false fronts, tunnels, runways, and breezeways, not to mention the pockets and spaces created by temporary construction, reconstruction and decoration.

A review of serious fires in which concealed spaces” was given as a contributing factor discloses that they are most frequently encountered in the occupancy-group of mercantile, habitational (multiple dwelling, apartment and hotel), storage and warehouse. Experienced fire officers are particularly suspicious of fires in structures that have had their “faces lifted.”

Why Are These Fire Especially Hazardous and Troublesome?

Because they complicate the business of fire attack and control and permit little fires to grow big, they are a hazard to life and property.

Fire at best is unpredictable, treacherous, uncertain. It rarely follows a set pattern. The hidden space is one of its most deadly and destructive allies—a hazard not only to owners and occupants of property, but to the fire fighter.

Concealed spaces provide passageways and channels between buildings and/or areas, to further the extension of fire and attendant smoke and gases and to place it out of easy, immediate control by the fire forces. Sometimes fire will bone and burrow its own concealed space, where it may lurk for hours, even days, before discovery.

Concealed spaces make for stubborn, persistent, hard-to-find-and-fight fires, which punish firemen because of the difficulty in locating the heart of the fire and determining its course of travel and its speed of spread. It is almost impossible to anticipate the direction of travel or the severity of fire which develops in hidden areas.

This complicates the task of attack and extinguishment. It makes it difficult to determine the amount and extent of fire control forces needed to subdue such fires. The chronology of fire department response to multiple alarm fires often attests this fact: when additional alarms are sounded some time apart it is frequently because it was impossible to immediately size up the nature and extent of the fire, or where it was heading, or what it was feeding upon.

The concealed or hidden fire may develop deadly conditions by melting off gas connections or power lines thus adding to the fireman’s risks. But its most dread characteristic is as the developer of backdrafts or explosions. The opening of a door, skylight or other vent—even remote from the fire, may furnish the necessary oxygen to the smouldering, sluggish fire that has been lurking in some concealed space, to give it sudden, explosive life, with tragic consequences. The more hidden areas there are for fire to propagate and build up heat and gases, the greater the possibilities of this trouble for the fire fighter.

Typical cockloft overhaul operation during fire in a six-story New York apartment. Axe, hook and claw tool are used to open concealed spaces. Note firemen wear gloves and do not bunch over weakened burned roof area.

Another troublesome characteristic of the concealed space fire is the difficulty it creates in overhauling and preventing re-kindles.

Fire streams may finally reach to hidden spaces and knock down the fire lurking therein, but unless those areas can be overhauled and investigated and those fires completely killed, the dormant fire may later rekindle with disastrous results.

In March, 1923, Providence. R. I., firemen were called to a fire in a six story building. They fought the blaze, in a ventilator duct in the kitchen, and on the third floor. It was considered extinguished about an hour later, but soon after a serious fire was discovered on the sixth floor, 70 feet from the flue where trouble had previously been encountered. Second, third and fourth alarms were sounded in rapid order, but despite the augmented forces the loss was heavy. Sprinklers which had been shut down by the department when the fire was thought extinguished and which were still out of service when the fire extended, contributed to the spread of the fire and heavy loss.

New York City had a serious apartment house fire, and Birmingham, Ala., suffered one of its heaviest losses in the burning of its then largest department store all because fire, which was once considered safely controlled, continued to spread via hidden channels.

It is not uncommon for fire to extend through structures protected by automatic fire detection and alarm systems, without causing the system to function. This happened in 1950 in Boston, Mass., where a fire in an old building occupied for paper storage and paper working, reportedly started in a concealed space near a fireplace. According to the N.F.P.A., which quotes the Boston Fire Department, the temperature in the building increased too slowly to operate the automatic fire alarm until fire broke out of the concealed space and flashed through the building. The loss on this fire was $1 million. The building’s concealed areas had no fire stopping and no sprinklers. Fire fighters were fortunately able to save exposures.

Different stores, but the same old connecting cocklofts spread taxpayer fire. Five alarms were sounded before stubborn, sneaky, early morning fire in this Bronx, N. Y., block was subdued. Fourteen stores wrecked; six firemen injured; loss about $250,000. Fire traveled through unstopped hidden channels.Fire communicated through hidden spaces to involve roof understructure in this hospital dormitory. Two dead, eight injured, but fire was kept from main hospital.

If any part of a building should be protected by fire detection and/or automatic fire extinguishing systems, it is these concealed and hidden areas. Yet for one reason or another, these vulnerable areas are often left unprotected, to become an invitation to fire.

New York City firemen will not soon forget the Lanes Department store fire of last March, where a delayed alarm, plus the peculiar construction, or arrangement of two five-story buildings and a “jumble of false ceilings” in the two buildings (including one of the “suspended-from-the-ceiling” types of fire breeders) gave the fire a head start on Manhattan firemen. These concealed areas provided a horizontal flue for fire travel, which continued notwithstanding the efforts of a five alarm assignment resulting in heavy loss.

Commenting on this blaze, the Department’s publication WNYF said “The delayed alarm and the maze of hanging ceilings had given the fire a head start, however, and as fast as the truckmen opened up the many concealed spaces, the fire, faster still, had raced on beyond.”

Illustrating bow fire can travel through concealed spaces peculiar to balloon-type construction. This is why it pays to double check cocklofts and attics in all serious basement fires in such buildings.Many hidden fires have resulted from ignition of floor beams by heat convection or contact. Fire can communicate to underside, or hidden areas of building via either adjoining of abutting floor beams, as shown in above diagram.

The irony of this fire was that a new, 4-story section of the department store had been sprinkled, but the hazardous old warehouse section had not.

It appears axiomatic that these out-ofthe-way spaces, if accessible, are invariably used for storage of combustibles. Not infrequently, firemen find the cause of their headache—speaking literally and figuratively—in subduing a particularly punishing fire, to be paints or other volatiles which have been stored in some out-of-the-way spot. It seems to be the practice today for merchants, manufacturers and warehouseman to load up every inch of space they can find in their places of business with stock, most of it parked and packed, unfortunately, with little or no thought as to its combustibility or how, if it should become ignited, fire fighters could ever manage to reach it and extinguish it.

The fires we are describing have another unfortunate after-affect. They contribute more heavily to water loss than almost any other kind of blaze. The reasons should be obvious. Even with the best of respiratory protection, with portable lighting equipment and other modern fire control facilities essential to fast, coordinated attack, stealthy fire can propagate and flourish out of sight, giving off smoke and fumes sometimes out of all proportion to the magnitude of the blaze itself. Firemen under these conditions can hardly be blamed for directing streams toward where they believe the fire to be located, even if they can’t see it.

The condition is aggravated by the tendency to partition off basement and attic storage places, and other floor areas, and to permit some sort of openings between the spaces or cubicles. Every municipal fire officer has experienced fires where, despite fire streams that apparently were hitting the blaze they continued to spread. The simple truth is that the extinguishing agent was not reaching the fire. Where the blazes are the upper parts of structures. under these conditions heavy water losses are bound to result.

Roof structure may have vulnerable concealed areas. Hidden fire may travel throughout entire roof area before detection. Note bulkhead construction. Quick venting through bulkhead scuttle or trapdoor will slow fire spread through these concealed spaces.

Fire Fighting Operations Where Concealed Spaces Are Involved

Fire department inspections should uncover at least the more evident hazards such as we have described. Notwithstanding the fact, however, that the hidden hazards are known, and the department has taken measures to shape fire attack strategy accordingly, it frequently happens that operations fail to proceed according to plan.

Sectional elevation of typical taxpayer, showing vulnerable hidden cockloft and cornice through which fire can travel if building is not fire stopped.

This happened in the case of the Lane Department store. From deputy chiefs down, firemen of the immediate area were said to be aware of the hazard existing in the layout, and plans of attack in case of fire had at one time been developed. But plans cannot anticipate every contingency, such as delayed alarms. No plans can anticipate all possible unfavorable developments. But that is no reason for not at least making the inspections, and preparing the attack plans.

Where there may be, or are suspected hidden areas involved or that may be involved, or where size-up fails to locate a logical source of the smoke and gases that are present, the spread of fire through concealed spaces may be anticipated, and while no effort should be spared to ferret out the source of the fire, immediate steps to prevent its extension, or its possible extension, should be taken.

Size-up of the occupancy, exposures, direction and velocity of wind, condition of the weather weighed against the forces immediately and later available, and the degree of involvement, should determine these steps. The first one would be, if conditions seem to justify, to summon additional help. It may be that rescue units or additional forcible entry or other special equipment is wanted. But in this situation it is well to remember the old fire fighter’s dictum: “You can always give good excuse for calling for help that was not needed, hut you can never excuse not calling for help when it is needed.”

Put in other words, the need for additional help may not be immediately plain but if there is the slightest doubt, of its want, it’s better to play it safe and not delay the calling.

Thus, fast, thorough size-up is indicated.

Obviously, fast attack, i.e.: the effort to quickly get at the seat of the fire, while laying plans to control extension through known, or believed-to-exist hidden spaces, is indicated. If, as said, fire isn’t showing, an immediate investigation of all hidden areas which might be involved is called for.

Indications that fire has involved hidden spaces are: (a) hot walls; (b) blistering of paint or wall paper; (3) discoloration of walls, wainscoting or covering; (4) smoke emitting from partitions some distance from fire (where smoke can go, fire can go!); (5) unaccountable heat in an area; (6) crackling or other sound of fire behind a wall, ceiling or partition; (7) sudden cut-out of light circuits for no apparent reason; (8) persistent flare-ups of fire from some outlet, electrical ventilating, heating, air conditioning, regardless of water being directed at or into outlets; (9)

Fog and applicator used to kill fire in hard to reach ceiling space. Sometimes the only way to reach fire in concealed hidden areas is to pull ceilings. Judicious use of low velocity fog applicator here simplifies this operation, reduces cutting and use of solid streams.

When streams apparently have no effect on fire (such as when operated through windows or other openings.)

Don’t belittle insignificant little fires, such as those in closets, nooks, and hidea-ways. Study shows that a number of serious blazes have developed, because of failure to perceive the potential hazards in what initially appeared to be trivial fires. By the same token, many small fires have developed into large ones because the first attacking fire forces either would not or could not carry their search for the fire to a conclusion. In other words, because of smoke, or fumes, or for some other reason, the first precious minutes of attack were wasted and the fire found its way into concealed places to develop into multiple alarm proportions.

In sizing up a fire building the experienced fire officer consciously or ununsciously observes certain fundamentals which may have a bearing upon possible concealed fire. The location and the architecture, together with the firm’s name on the structure, afford an inkling of occupancy and contents. Concealed spaces may be suspected in buildings that have obviously been “modernized” i.e.: had their “faces lifted.” The type of construction too, will often indicate possible routes of fire through hidden spaces; witness the rows of connected taxpayers, the two-family-dwelling housing, and the like. In industry, and in some mercantile occupancies, dividing and party walls may indicate broken up areas, as well as fire stops. The exterior may show another possible avenue of concealed fire travel, the cornice. Earlier files of this Journal contain references to many large fires which got away from the fire forces because the fires traveled through unstopped connecting cornices or other ornamental work. Cornices can be perfect hidden flues for fires.

Dividing walls and partitions may not extend through the top and roof of a structure, thereby offering fire opportunity to jump from one concealed space to another. Another avenue of fire spread, via hidden spaces, is found in the overlapping beams of building foundations. If smoke or flame indicate that fire has worked its way into these foundation areas, the procedure is like that wherein connecting cocklofts are suspected: to get well ahead of the fire and prevent extension.

Even if there is no evidence of fire in or near known concealed spaces adjacent to the fire, it is well to check on all those that are known, particularly hanging ceiling and platforms for example.

It should hardly be necessary to remind a fire officer to investigate the space between studding, and behind plaster-and-lath or other coverings which can prove possible avenues for fire extension. It is well also to emphasize the wisdom of getting above any serious fire in an un-stopped combustible structure. In short, before picking up, be doubly sure that the basement or ground floor fire hasn’t in some unaccountable way played leap frog to involve the attic or other upper areas. Any false work, built-out walls or extensions, anywhere near the fire area, should be investigated.

Another reason for this thorough post-fire survey is that it may just possibly disclose evidences of arson, where fires were set in more than a single location in a building. It is true, this takes time and may not be in line with the rule to speed the return of company units as quickly as possible. Nevertheless, it is a good practice and, now that radio is rapidly coming into widespread use, the company can go back into service on the fire ground while the post fire check-up is being made.

We have mentioned fire which finds its way into concealed spaces. There is the fire which originates in these areas, and breaks out into other areas to possibly catch the attack forces in the rear, perhaps even cut off escape of fire fighters. This has happened. For this reason it is well for an officer to anticipate, where possible, the direction of fire travel and possible involvement of hidden spaces. It is well to give thought to the relation of these hidden areas to vertical and lateral arteries, shafts, passageways, stairways, etc. and consider the possibility of an enclosed or hidden fire breaking out, to communicate within these arteries.

Not all fires in concealed spaces travel upward; fire can and often will travel downward as well as up, and laterally in and through hidden spaces. In this connection it is well to remember that every fire has six sides: front, hack, two sides and top and bottom.

In fighting fires where there is a possibility of extension through concealed spaces (and this applies to almost every type of occupancy) if it is indicated the fire has been burning for any appreciable length of time, be suspicious of possible hidden extension, and be wary of backdraft. Even if the main body of the fire has been controlled, institute inspection to determine if fire has worked into and through partitions and walls, or any connecting areas. If there is the slightest evidence of such extension, if unexplained smoke continues to emit some distance from the main body of fire, for example, check thoroughly, open up suspicious spaces and have lines and men ready to meet and control any fire.

(Continued on page 972)

A suicidal gas blast caused this destruction. Fire fighter is opening up damaged wall area to ferret out possible fire.

Concealed Spaces

(Continued from page 929)

Lurking Smouldering Fires Conducive to Backdraft

One of the most dread hazards of fire fighting is backdraft. Backdraft may be caused by the ignition of pent up gases suddenly brought into contact with oxygen of the air. The gases may build up great pressure in a confined space as a by product of a smouldering, slow burning fire, with just about enough oxygen available to prevent the fire from dying out. The quick opening of that space may release the gases to mix with the outside air, with resultant, possibly serious, explosion.

No matter how careful fire fighters may be in effecting openings in any structure that has been sealed up and in which fire has been “cooking,” backdraft, or a kindred blast may occur. Although the concealed space fire is not necessarily a breeder of backdrafts, it is frequently associated with smoky fires in hidden areas where pressures have built up, undetected.

Attack on fires in concealed spaces calls for ample forcible entry tools, special hose fittings, such as partition nozzles distributors, applicators, cellar pipes, etc.

Even the best fire department under certain conditions may find itself lacking in such common tools as axes and plaster hooks.

Although not all fire chiefs will agree with the practice, small hand lines (such as 1 1/2-in. hose) are proving increasingly acceptable in going after and controlling small fires in concealed spaces. So, too, is the use of water fog and wet water, the latter particularly where fire has burrowed into storages and stocks where ordinary water will not penetrate. Where a few men and limited number of lines must attack a fire that is extending through hidden arteries, possibly over a considerable area within a structure, the 1 1/2-ineh hose with suitable fog nozzles and fog applicators proves a real asset. Two men are usually sufficient to make openings and operate the fog or straight streams into and within the confined spaces. Of course, small lines should be backed up with heavier lines.

It is generally next to impossible to fight these lurking fires without making openings in floors, walls and/or ceilings. It may quite conceivably be necessary to open up far in advance of suspected or actual fire, or to create openings over a broad area to inspect for possible fire in a building. A company, or department may be unjustly criticized by property owners or tenants, or both, for apparent needless destruction of property. Obviously, the necessity for such exploratory cutting and other destruction should not be a license for “tearing the house apart.” It calls for a bit of educating of the public by the fire service. At least one large fire department. Los Angeles, has made a sincere attempt to explain to the city’s citizens just why it may be necessary to cut a hole in a roof in order to locate and extinguish a fire that may be hidden in the basement.

The experienced fire officer never underestimates the possibility of concealed fire reigniting and breaking out of concealed areas or pockets. That’s why he devotes so much time to overhauling. The bigger the fire extinguishing operation, (the more property involved, etc.) the more important it is to take time to overhaul the structure and kill all lurking, smoldering fires. Studies of overhauling emphasize the importance of searching for fire in such concealed spaces as window frames, casings and closets, over-stuffed furniture and the like. Out-of-the-way places where fire may hide are found in the contents of buildings as well as the buildings themselves. A serious hotel fire resulted from the failure to overhaul a bureau drawer in which fire or sparks remained, following a blaze that burned out the room interior. The rekindle required multiple alarm response.

Who Is to Blame for These Conditions?

There is no particular secret about the causes for these conditions. The blame must be shared by a number of interests, including the fire service itself.

Beginning with the property owner who, for reasons of economy or otherwise, insists upon these breeding places of fire, and refuses to safeguard them with adequate fire protective systems, to the architect and the builder who “go along” even when they know conditions constitute a hazard, we find the trouble stemming right at the source. Next, there are the tenants of the structures, permanent and transient, who contribute their share either by contributing to the hazard or by failure to report on the hazards and insist upon their elimination.

Civic officials must share blame because of their unwillingness to adopt building codes with teeth in them or, where such codes exist, to enforce them.

Some blame must be shared by fire departments and fire prevention bureaus which fail to locate such conditions or, where they are found, to fight to eliminate them. The hazard of the concealed space continues to exist, if not flourish, in many cities because municpal authorities so complicate and handicap the fire department’s efforts to unearth and correct such conditions that inspections are more or less perfunctory, if they are made at all. Fire prevention bureaus should (1) be under fire department jurisdiction, and even more important (2) they should have full and complete jurisdiction over inspections of existing buildings, and the legal authority to determine violations, bring violators to court and get convictions where violations are not corrected.

Many fire chiefs believe responsibility lies also with insurance companies, which persist in insuring risks which are known to constitute hazards.

In some quarters there is a tendency to blame fire departments for failing to locate these hidden hazards or, where found, to notify the proper authorities of their existence. But speaking for the fire service, it must be pointed out that, in addition to the conditions above numerated, the average municipal department has thus far been able to conduct little more than infrequent detailed inspections of properties and occupancies wherein such conditions are most likely to be found. Although two-way mobile radio on fire apparatus is encouraging broader and more detailed inspections on the company as well as departmental levels (by keeping inspecting companies ‘in service’) such use of modern radio communications is at present the exception and not the rule. The average department is too shorthanded in personnel to maintain intensive inspection work and to prosecute violators of codes and regulations.

There is still unlimited opportunity for fire departments to put into effect the policy of fighting fires “three ways” i.e. : (1) before they happen (2) when they occur and (3) after they have occurred.

After the Fire

From studies of the beforementioned incidents several additional conclusions are reached.

Each fire in which origin and extension was either due to, or aided by hidden spaces, might well be the subject for a fire department “post mortem” or critique following the incident in question. Conditions that created the initial hazard at the outset, and which handicapped the fire control and extinguishing efforts, should be reviewed and studied, at least by the officer personnel, if not all units.

Each such fire should produce evidence which should be taken as lessons to govern future policies and operations. In some cities the case histories of these fires furnish the basis for promotional examination questions, as well as for lectures on fire control and extinguishment.

At least one fire chief of our acquaintance makes it a practice to encourage suggestions from his official personnel on how to locate and combat these conditions. These ideas are discussed in pre-fire as well as “post mortem” conferences and often result in effective solutions of problems, which are passed .along to the rank and file as orders and regulations.

A number of chiefs make it a practice to maintain a ‘live’ file on the subject. They get all possible information relating to it from the fire records of their own departments and outside; they conduct special studies of outstanding cases and use the information, where feasible, to secure publicity on this factor of fire spread as affecting local fire losses, and posible loses. The idea is to inform the public generally of the dangers presented by unprotected, “hidden areas” and of storing combustible materials or otherwise using the areas so as to contribute to the propagation and spread of fire therein.

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