Primary Ventilation: A Review

The critical role ventilation plays in successful firefighting operations makes ventilation a good drill topic for firefighters of all ranks and levels of experience. When ventilation is not performed or is improperly executed, the results can be catastrophic.

Following are some basic building types found throughout the country and ventilation tactics you should consider when responding to these structures.

SINGLE-FAMILY DWELLING

The single-family dwelling still accounts for one of America’s most serious fire problems. The initial operation should be horizontal ventilation coupled with an aggressive search effort. Primary ventilation opposite the advancing hoseline attack allows an aggressive attack to be made toward the seat of the fire and allows search teams to penetrate all areas of the dwelling. Communication and coordination with the advancing nozzle team are basic to this operation. It’s often been said that we vent for two basic reasons:

  1. We vent for fire, meaning that we vent to facilitate the movement of the hoseline attack into the fire area. We do this by releasing the products of combustion-heat and the highly flammable, toxic gases and smoke-to decrease the flame spread to reduce the possibility of a flashover, backdraft, or smoke explosion.
  2. We vent for life, meaning that during an aggressive search effort, we vent to improve conditions for a known life hazard while knowing that we may escalate the fire condition.

In either case, communication among personnel on the fireground is key. Fires below grade in a single-family dwelling present difficult problems because of their subterranean location and lack of openings. However, a basement fire can expose an entire dwelling, its occupants, and operating firefighters to fire and all the bad products that go with it. Since fire heat and gases naturally rise, expedient, efficient ventilation is essential. Consider the following ventilation tactics:

  1. Initiate ventilation with the advance of the attack line.
  2. Once the attack line is moving to the seat of the fire, the search team leader should coordinate ventilation with the attack line and the incident commander.
  3. Use available openings to vent the basement area, exterior basement doors, windows, and other types of openings.
  4. If there is only one route or stairway to the basement, consider cutting the first floor with a power saw to help relieve conditions in the basement. (Consider cutting near a window to facilitate ventilation; use a hoseline to protect the operation and limit fire extension to the floor above.)
  5. Ventilate first-floor windows. In two-story, single-family dwellings, consider venting second-floor windows to alleviate the upper floors because of the amount of mushrooming that will occur because of the open stairways.
  6. Basement fires often extend by various vertical arteries. When venting above the fire, check for extension in these arteries early and often, especially in older wood-frame structures.
  7. In all ventilation efforts, use caution in preventing self-inflicted autoexposure to the floor or floors above by overly aggressive ventilation.

In multistory single-family or multifamily dwellings, use a combination of vertical and horizontal ventilation. Ventilation operations should focus on improving conditions inside the structure as quickly as possible to allow search teams to conduct aggressive searches for trapped civilians and advance the attack line. The location of the fire and the type of roof construction, flat or peaked, will often set the parameters for ventilation.

In a peaked-roof, multistory dwelling, timely horizontal ventilation of the windows is the most efficient, effective way to vent. The point here is that because of the nature of the peaked roof, ventilating the roof will take time. That is not to say that we will not open the roof but that the initial emphasis on horizontal ventilation will allow search teams to move aggressively through the dwelling coupled with an aggressive hoseline advance. This one-two punch of the hoseline advance and immediate horizontal ventilation allows search teams to get to most areas of the dwelling quickly. An additional thought on peaked-roof operations is that skylights at roof level are being found in newer or recently renovated single-family dwellings; the immediate venting of these skylights will also improve interior operations dramatically.

Personnel assigned to the search functions, members assigned to teams as part of this vent-enter-search (VES) concept, often perform initial ventilation operations. They must be aware of attack line movement and advance. If there is fire extension to the attic or cockloft area of a peaked-roof dwelling, roof ventilation will have to be an early available tactic. Following are some basic size-up points related to venting a peaked roof:

  1. Assess the pitch and covering of the roof. If it is not safe to walk on, work from an aerial platform bucket, an aerial ladder, or a roof ladder.
  2. When assigned to vent a peaked roof with a power saw, work in two-person teams (one saw operator and a backup). Pull all the sheathing, and ensure that there are no obstructions below.
  3. Bring the following tools for this operation: a power saw, a halligan tool, a six-foot hook, and a radio for each member. (An ax is a must here. If the start cord breaks and a second saw isn’t available, start chopping. Also, because of the depth of attics in peaked-roof dwellings, the proper size hook could be a 10- or 12-foot hook to reach the ceiling below.)
  4. Attempt to cut as close to the fire’s location as possible without cutting off your escape route.
  5. Once you have made your cuts, ensure that you have pushed down the ceiling below to assist with the upward draft from the structure’s top level.

MULTIPLE-FAMILY DWELLING

In multiple-family dwelling structures with a flat roof, how and where to vent initially depend on the fire’s location. Consider a three-story building with a commercial-type occupancy on the first floor and residential apartments above. If the fire is in the first-floor commercial, a heavy smoke condition will develop on the upper floors, immediately exposing these floors to heat, smoke, and all the bad stuff that goes with it. Immediately implement roof-level ventilation of bulkhead doors, skylights, shafts, and other vertical openings.

The primary tactic: The basic premise of this tactic, which has been taught for more than 100 years, is to alleviate the conditions in the center hall and rooms off the center hall, allowing teams to search above the fire. In fact, in most buildings with the center-hall type of layout, the area at the termination point of the stairs provides the means through which you achieve that important initial vertical ventilation.

Much has been written over the years about critical roof position and the importance of “getting the roof.” This critical assignment was drilled into your head as a young truck firefighter. Getting to the roof and immediately vertically ventilating a multistory building occupied by civilians is one of the most demanding functions on the fireground.

The most important lesson to pass on at drill time is the importance of getting there. Once you are on the roof, look for the natural vent points (skylight, scuttles, bulkhead doors). Opening these critical arteries is the first task. Then, after surveying the structure’s perimeter, communicate with the interior teams to see where and if you need additional horizontal ventilation of the upper parts of the structure.

STRIP MALLS

The lightweight structures in today’s newer strip malls present a new challenge from a ventilation standpoint. Many of these structures are constructed of lightweight steel trusses with Q-decking as the top layer or gypsum-type planking. Because of its lightweight construction and early susceptibility to collapse, there has to be some type of risk management relative to whether troops should be committed to the roof. That being said, from a ventilation perspective, the first-arriving units should ask themselves some basic size-up considerations from a ventilation perspective:

  1. Has the fire communicated from the contents to the structure?
  2. What ventilation points are available at the roof level?
  3. Has horizontal ventilation been performed?
  4. What is the life hazard on arrival? Are firefighters the life hazard?
  5. What is the fire condition (light, medium, heavy)?
  6. What personnel considerations are involved in implementing the initial attack?

Lightweight roof construction does not lend itself to power-saw operations. In fact, you don’t want to use a power saw on a lightweight roof. Using the power saw will continue to compromise an already weakened roof. As a volunteer firefighter, I remember cutting a lightweight roof in the early 1980s and having the lightweight tin fall inward while all the bad stuff came blowing out of the hole. That, one of my earliest experiences with lightweight construction, taught me to have incredible respect for these dangerous buildings.

Vent tactics for a lightweight building include the following:

  1. If personnel are sent to the roof, look for natural vents: skylights, scuttles, or any other vertical artery that will give you vertical ventilation.
  2. Remember to force the rear door of the tenant space to allow for horizontal ventilation and a secondary means of egress for firefighters.
  3. Consider venting the large plate glass windows as soon as possible. Coordinate this with the hoseline operation. Remember, even if it’s just a contents fire, rest assured it will be lights out inside the structure. Venting these windows early will allow the line to advance and the search teams to move.

Some considerations when going to the roof of a large lightweight constructed roof include the following:

  1. Have a second means off the roof-another portable ladder or an aerial device.
  2. Assign personnel in teams. The initial team should be two firefighters; they should be equipped with the tools necessary for the task: a six-foot hook, an ax, a halligan, and a radio for each member.
  3. Give the IC the layout of the structure.
  4. Look for and open any vertical arteries that will allow the bad stuff to go out. Communicate with the inside forces.
  5. Many of these structures have windows along the top of the wall, right below the roof line. These windows allow additional light inside the structure. Vent these windows from roof level. In this operation, you are performing a combination of horizontal and vertical ventilation.
  6. Remember, the lightweight commercial building is a different structure from the older taxpayer building of brick and masonry. These roofs were constructed of larger and heavier structural members and could withstand more of the effects of a fire, allowing us to perform saw operations to help control cockloft fires and give us more vent openings. Also, the heavier nature of these structures allows the vent teams using power saws to cut as close to above the fire as possible. The mindset is totally different for a lightweight building.

•••

Primary ventilation is a key component of the fireground attack. Take time to evaluate the buildings in your district. Look at them from the ventilation perspective.

Tom Donnelly is a lieutenant assigned to Rescue Company 1 in Manhattan and an instructor with the Fire Department of New York’s Technical Rescue School and the Suffolk County (NY) Fire Academy. He has been a volunteer firefighter with the Deer Park (NY) Volunteer Fire Department for 22 years. He has a bachelor’s degree in human resource management from St. Joseph’s College in Brooklyn, New York.

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