Recognize Need to Vent Roof And Open It Up Immediately
DEPARTMENTS
The Volunteers Corner
One of the most deplorable sights on the fireground is to see a hole put in a roof after the fire problem has been resolved. When vertical ventilation is required, it is needed as part of the initial attack—not as an afterthought.
Sometimes I think roofs are opened to assuage the conscience of an officer who knows that he should have ordered the opening made long ago. In most cases, the fire would have been extinguished much sooner and with less damage if the roof had been opened with the arrival of the first companies.
If you are going to save a sizable portion of any building, you have to get hose lines inside, and when the heat is intense enough, only adequate ventilation and a high enough water application rate will permit you to get a hose line inside and keep it moving forward. Sometimes horizontal ventilation is adequate, but there are other times when vertical ventilation is vital to a successful attack.
Recognizing the need: Sometimes I am asked how to recognize a situation that requires the opening of a roof. If you have been an intelligent observer of past fireground conditions, believe me, you will know instantly when a roof has to be opened. The vast majority of vertical ventilation errors are made by not opening up a roof at the start of the initial attack. On the other hand, seldom is a roof opened needlessly upon arrival on the fireground. The useless openings are usually made long after they can have any effect on the outcome of the fire.
There are some indicators that shout, “Vent the roof!” The most serious from the standpoint of the safety of the fire fighters is a backdraft situation in which smoke is pulsing out around windows, doors and from eaves. The building is fully charged with smoke and the window glass is brown and too hot to touch. Open a door and an engine company may be blown into the street. Open the roof first to vent the carbon monoxide and the engine company can then enter to extinguish the fire.
In a single-story, taxpayer-type mercantile building, fire from one of the several stores may be into the cockloft when the first fire companies arrive. To prevent the fire from mushrooming throughout the cockloft and dropping down into all the stores, the roof has to be opened over the involved store. The hole in the roof will let the searing fire gases flow harmlessly to the atmosphere instead of supporting the extension of flame over more of the cockloft.
When fire has taken hold of a two or three-story, wood-frame house, consider the buildup of heat under the roof. You can’t tell what the temperature is under the roof, but your experience will give you a good idea of whether cutting a hole in the roof is the only way to get the heat out before flashover takes place. Opening up the roof also may be the only way to reduce the heat sufficiently for men to advance lines to the upper floors. Under such conditions, horizontal ventilation may be impossible or inadequate—or both.
Helping those inside: When those trapped inside a building are facing death from the hot fire gases, a large hole quickly cut in the roof can buy a lot of time for rescue work. The amount of heat will be reduced, making the situation more tenable for those still conscious, and the lethal gases venting out the roof will allow an inflow of outside atmosphere to increase the time before asphyxiation can make rescue efforts useless.
There are times when there is reason to believe that horizontal ventilation will be adequate to save all the endangered lives, but we can’t be sure of it. When this doubt exists, vertical ventilation should be ordered immediately because the people inside may not have enough time to live to see whether horizontal ventilation will be adequate—or whether it can even be accomplished in time.
Sometimes roofs have skylights, scuttles, housing over stairs and dormer windows. While these do not often provide the amount of ventilation that a 4 X 8 or even larger hole in the roof will provide, they should be opened up to give added ventilation. One can open up several such built-in ventilation possibilities while others are cutting a hole in the roof. Also, check automatic vents that may still be closed. Opening up housings over elevator shafts used to be a means of providing ventilation when there was an iron grill floor at the top of the shaft. In modern buildings, that floor is now usually poured concrete with holes just large enough for the elevator cables.
Make it big: Once the decision has been made to vent the roof, don’t have any qualms about making the hole as large as possible. The only reason for cutting the roof is to get the smoke and heat out of the building. Therefore, the hole should be large to get as much of the hostile atmosphere out of the building in as short a time as possible.
Whether you use a power saw or axes, cutting a roof is work, so you want to get the most out of the work you do. A 4 X 4-foot hole requires 8 linear feet of cutting to make a 16-square-foot hole. An 8 X 8 hole does a real ventilation job and requires 16 linear feet of cutting—twice as much—to make a 64square-foot hole—four times the opening of the smaller hole.
Before you take a power saw to a roof, start it on the ground. If the saw doesn’t start, then there would have been no point in carrying it to the roof. After the saw starts, let it run briefly, then shut it off and take it to the roof. It will probably then start with the first pull, and when working off a roof ladder, that is something to cherish.
