When Roof Should Be Opened Make a Large Hole Immediately
departments
The Volunteers Corner
For some reason, reluctance too frequently hobbles the decision to open up a roof when the fire situation demands vertical ventilation. The result is that because of the fear of doing excessive damage, fires that should have been controlled destroy buildings.
When excessive heat rises to the roof, mushrooms and starts to bank downward, the immediate effect is that any occupants are in danger of losing their lives and fire fighters will find it difficult or impossible to advance hose lines into the building. The end result is that the fire loss—and unfortunately sometimes the life loss—is greater than it need be because too much consideration was given to the cost of roof repair. Instead, consideration should be directed at minimizing the total cost of the fire.
Opening up a roof is sometimes the only effective way of rapidly reducing the temperature in a structure. At the same time, vertical ventilation that allows trapped heat and smoke to rise out of a structure has a chimney-like effect that brings into the building at lower levels the outside air containing the oxygen so vitally needed by occupants who may be unconscious or trapped.
Make it big: If you were to remember only one bit of advice about vertical ventilation, it would be: “Make the hole in the roof large!” I’ve seen a lot of roof holes that are too small, but I’ve never seen one that is too large.
Roof openings should be at least 4X8 feet—and preferably 8X8 feet. Remember the larger the hole, the more effective the ventilation. Furthermore, larger openings require little additional cutting in relation to the additional number of square feet of opening obtained. For example, a 4X4-foot hole requires two 4-foot cuts, a total of 8 feet, in a board roof deck to provide 16 square feet of opening. An 8X8-foot hole requires two 8-foot cuts, a total of 16 feet, hut the area opened is 64 square feet—four times as much opening area for only twice as much cutting.
When you are working on a plywood roof deck, look for the butt joints of the plywood sheet from which you are removing the roofing material and then continue removing roofing material to take out at least one 4X8 plywood sheet and hopefully even two sheets.
When you encounter a built-up roof, don’t try to make any cuts until the roofing material has been lifted off. Use an ax to cut the perimeter of the roofing material you’re going to remove and then pull it off with the pick head of an ax and the pointed end of a claw tool. A pike pole and even a flat shovel can be useful in lifting the roofing material so the ax pick head can get a bite t hrough the underside of the roofing material.
As you pry the wood or composition deck loose, work with the wind at your back as much as possible and remove the deck so that you first open up the portion of the hole that is farthest from you. In this way, you will be shielded as much as possible from heat and flame by the remaining roof deck as you work away from the increasingly larger opening you are making.
Let it burn: When you use a power saw to open up a roof, it’s advisable to first start the saw on the ground and let the motor run for a few seconds. Letting the motor run and t hen shutting if off before taking the saw to the roof greatly ensures the certainty of starting the saw while on the roof. It isn’t so bad on a flat roof, but starting a balky saw on a pitched roof is not a pleasant task. Also, if you can’t start the saw on the ground, a few feet of altitude won’t solve your problem.
The easiest way to get roof ventilation is to let flames starting to show on the roof continue to burn. The flames will open as large a hole as you want and, best of all, you know that the hole is at the hottest part of the roof—the spot where ventilation is most effective.
Once you have a hole in a roof, don’t nullify your work by allowing anyone to put a hose stream into the hole. Let flames reach for the sky—even low clouds won’t get singed and I don’t know of anything else that can he harmed. The hot gases in the building are leaving—along with the flames—and that’s what you were trying to accomplish. A stream directed into a roof opening keeps the hot gases inside the building and if you do that, you might just as well have left the roof intact.
Where they are present, scuttles and skylights should be regarded as an immediate ventilation opportunity. Opening them up can provide quick ventilation, but the total area opened may not be adequate for a really serious fire and the roof may still have to be opened. Also, skylights sometimes are not located where roof ventilation is most needed and opening them may pull fire where you don’t want it to go. The ladder company officer must evaluate the situation.
Generally, you will want to open up a roof over the hottest part of the fire. However, there are times when you will want to open up a roof to draw fire and smoke away from the main fire area to protect occupants endangered on the far side of the fire.
The chief in charge should consider the stability of the roof before he orders a ladder company to open it up, and then it is necessary for the men to further evaluate the roof condition before they start opening up.
With all these things in mind, remember that it is better to open up a roof too soon than too late.
