VENTILATION TACTICS FOR PITCHED WOOD ROOFS

BY MARK WATERS

As the firefighter assigned to perform vertical ventilation of a pitched wood roof, you should first determine the best method to accomplish this. Each fire department should be familiar with a variety of methods and tools to vertically ventilate structures with this type of roof. Ventilating such structures can often be an arduous task that requires knowledge of building construction, ventilation techniques, and the tools of the trade. In many cases, vertical ventilation requires an extended time to complete and is not always the best option. This task should only be assigned to experienced firefighters familiar with the equipment available and the various methods for completing the task safely.

On receiving the order to ventilate a structure with a pitched wood roof, the firefighter must determine the safest and quickest ventilation methods to use under the fire conditions present. Often, vertical roof ventilation isn’t completed until the main body of fire is knocked down or after companies are sent to rehab. Other ventilation options should be considered before firefighters commit to performing roof ventilation.

Fire departments throughout the United States have developed standard operating procedures that address operations involving wooden roofed structures. Many departments discourage vertical ventilation because of the time it requires, while others require it. Some of the departments with response districts that include pitched wood roof structures also discourage the use of power saws. Other departments don’t perform vertical ventilation at all because of the safety hazards involved in operating on such roofs.

However, there are many times when vertical ventilation of pitched wood roofs is necessary to relieve the interior firefighters from the heat, smoke, and gases they are encountering.


1. Photos by author.
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SIZE-UP

When the incident commander (IC) sizes up a fire building with a pitched wood roof, he should consider the following basic questions before sending a ventilation team to the roof:

  • Is vertical ventilation the most effective tactic to relieve firefighters operating in the fire building?
  • Are the resources available to complete vertical ventilation in a timely manner?
  • What are the interior and exterior building fire conditions?
  • What is the fire’s location—is it directly under the roof?
  • Is the roof currently stable enough to support firefighters operating on it, and how long will it stay that way?

The IC should have firm answers to these questions before assigning the team to roof operations.


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Once the IC has committed to vertical ventilation, the ventilation team should consider the following in its operations:

  • Size up. Consider the roof’s construction, stability, presence of natural openings, and any other hazards including power lines that might affect operations.
  • Laddering. Deploy aerial, ground, or both types of ladders to the roof. Use a roof ladder on all pitched wood roofs.
  • Full protective equipment. Use full protective equipment including SCBA.
  • Means of egress. Find a secondary means of egress, and maintain access to it.
  • Ventilation. Ventilate at the highest point above the fire.
  • Protective hoselines. Position a hoseline team in place to protect the ventilation team.
  • Ventilation holes. When cutting the ventilation hole, consider the following;

—Start at the point farthest from the roof ladder and work your way back toward the roof ladder.

—Cut one large hole (e.g., a 4- 2 4-foot hole for residential structures) instead of several small holes.

—Once the hole is cut and the roofing materials are removed, push the ceilings down with a hook.

* Fire streams. Once ventilation is complete, never aim fire streams into the ventilation hole if interior crews are operating in the structure.

* Exit immediately. Get off the roof as soon as ventilation is completed.

TOOLS

Vertically ventilating a structure requires a variety of tools. In many cases, some tools, such as power saws, are dangerous to operate on pitched wood roofs even with proper safety precautions. Although power saws are very effective for cutting through pitched wood roofs, they may have to be operated in areas with limited to no visibility and under extremely awkward positions, making their use unsafe. Trying to maintain balance while operating a power saw is definitely not for the beginner.

However, there are many pitched roofs on which power saws could be operated safely, provided proper safety precautions (including anchoring or using a roof ladder) are taken. When the officer assigned to ventilation sizes up the roof construction, the roof’s pitch will dictate whether power tools should even be considered.


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Other disadvantages of using power saws include the difficulty in starting them on the roof, their tendency to stall when smoke enters the air intakes, and the danger of cutting through roof supports.

Fire departments have addressed these issues by requiring their firefighters to use an ax to perform vertical ventilation. Axes are always the go-to tool because they don’t have to be started, they work even when exposed to smoke, and they present minimal danger of cutting through important roof supports. One disadvantage of the ax is the physical energy required to use it. The user may become winded or low on air before completing the ventilation hole in the roof.

ALTERNATE TOOLS, METHODS, AND TECHNIQUES

Reciprocating saw. An alternate method to performing vertical ventilation on a pitched wood roof is to use a reciprocating saw. The fire service has adopted the reciprocating saw as the tool of choice in many situations, especially in vehicle extrication and rescue incidents. However, most firefighters do not generally consider the reciprocating saw as a ventilation tool. It is an effective tool that combats all of the negatives of the power saw in vertical roof ventilation. The reciprocating saw always starts, you can feel and hear the saw bog down when it is cutting into a roof structural member, and it isn’t affected by exposure to smoke.

Using a 24-volt battery-operated reciprocating saw will certainly complete the job, although an 18-volt saw is also adequate (photo 1). The demolition blade is the most effective one in penetrating the many layers of materials found on pitched wood roofs (photo 2).

Electric reciprocating saw. Although an electric reciprocating saw is capable of completing the job, its effectiveness may be offset by the time needed to run the power to the roof to operate the saw, entanglement hazards with the cord, and cord exposure to heat and flame.

Tool cache. The tool cache the ventilation team must bring to the roof in addition to the reciprocating saw should include a pickhead ax, a utility rope, and a minimum six-foot hook for pushing the ceilings down once the ventilation hole is completed. One ventilation team member should also carry a spare saw battery in his pocket in case the saw battery is not fully charged when starting vertical ventilation.


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This equipment combination is easily managed on the roof and shouldn’t place the roof ventilation team in awkward unbalanced positions that often result when using a power saw.

Once on the roof, one firefighter uses the small end of a pickhead ax to make a small hole in the roof (photo 3). The hole must be big enough to allow the blade of the reciprocating saw to slide into it to begin cutting. More than one small hole may be necessary if the user has trouble cutting over roof supports for a continuous line cut.

The ventilation team should follow the same guidelines for cutting ventilation holes as if they were using a power saw or an ax. The team should start at the farthest point from the roof ladder and make the cuts back toward the ladder or egress point. A 4- 2 4-foot hole is ideal for vertical ventilation of a residential pitched roof (photo 4).

EVALUATION

Fire departments evaluating this method for vertical ventilation of a pitched wood roof should also experiment to identify the type of reciprocating saw blades that work best for roofs in their districts (photo 5). Many manufacturers of saw blades sell wood, metal, bi-metal, and demolition blades. In evaluation, demolition blades were found to be the most effective in cutting through pitched wood roofs containing flashing, nails, and multiple layers of roofing materials. Some manufacturers call these fire rescue blades because of their effectiveness in rescue work.

MARK WATERS, a volunteer firefighter for 17 years, is assistant chief of the Oakdale (CT) Fire Department. He has been a career firefighter for the New London (CT) Fire Department for eight years and is assigned as a rescue specialist with Connecticut US&R Task Force 1. He has a master’s degree in fire service administration from Grand Canyon University and a bachelor’s degree in business, management, and economics from Empire State College. Waters is a graduate of the National Fire Academy’s Executive Fire Officer Program.

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