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Ventilation Basics by Structure Type



AP Photo/Mike Meadows
Los Angeles firefighters work to ventilate the roof of a furniture manufacturing plant in this file photo.
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Single-family occupancies
Most of our fires are found in residential structures. These structures can be isolated single-family, single-story structures or multi-level single family or duplex-style houses. In homes consisting of only one floor, the easiest rule to remember is to try to ventilate the smoke and heat out of an exit point close to the seat of the fire. This ensures we are going to limit the amount of smoke and heat damage to the interior of the structure.

  • Ventilation should begin as close to the room of origin as possible.
  • Open or remove those windows in the room of origin that are closest to the fire. 
  • Prioritize the removal/opening of windows to those where flames or pressurized smoke is already coming out of or where fire can be seen or heard through.
  • If more ventilation is required, consider other windows for complete ventilation. Base the amount of damage to windows and roofs to the amount of ventilation required to perform ventilation adequately.
  • Try to reduce the amount of damage if possible. Taking out all first-floor windows when fighting a single room and contents fire may be overkill.
  • In single family residences, fires in the attic or cock-loft should be checked for fire spread, especially of they are directly over the seat of the fire.

In two-story residential units with fires on the first floor, again utilize windows closest to the seat of the fire. Consider ventilating the second floor as soon as possible. When the fire is on the second floor, ventilate this floor first. If possible, start by ventilating the outside windows of the room of origin first and coordinate the movement of air within the structure.

  • Keep the doors to rooms closed once searched and especially control the doors to rooms where windows have been taken out. Control the flow of air from the inside to the outside if possible.
  • Remember to prioritize fires in the attic or cock-loft, especially if working in duplexes or townhomes. Check for extension into other units quickly to assist with confining the fire to the unit of origin.

In single-family residences, townhomes or duplexes, fires in an attic present a different challenge. If possible and safe, consider attacking the fire from inside the structure. Ensure that crews are not operating under a truss system that has been exposed to flame for more that 10 minutes when possible. Ventilating an attic can be performed by utilizing gable vents, multiple attic vents. If vertical ventilation techniques are considered, open the roof near the peak over hot spots. Ensure crews check for roof deck stability.

Basement fires present fire attack crews with unique challenges. They may have to advance their attack line through the stairwell that is also acting as the chimney for the products of fire. Fires in small buildings may be ventilated through available basement openings, such as windows or floor grates.

  • Ventilation must be coordinated with interior attack crews.
  • When possible, utilize exterior basement entrances, otherwise the main stairwell is your access. If utilizing the main stairwell, ensure the stairs are structurally sound, and stage a firefighter at the head of the stairs to maintain contact with the attack crews and to assist with moving hose-lines into the basement.
  • Consider cutting ventilation holes in the first floor near exterior walls for ventilation of heat/smoke from the basement. Ventilation of the first floor may assist interior crews in advancing attack lines into the basement.

Multi-family/business occupancies
In multiple-family residential units and business structures, larger square footage presents multiple challenges from a ventilation perspective. These challenges regarding roof operations, ventilation of larger square footage floor plans, increased fire load from businesses and multiple residences as well as connecting buildings force the ventilation group supervisor to approach these structures in a more cautious manner.

When performing roof ventilation on larger structures, refrain from using interior stairs for access. Victims and attack crews will require their use. However, interior stairwells of adjoining structures that are attached to the main fire building may be utilized to access the roof. If interior stairwell use is not possible, look for fire escapes. When none of these are present, use of ground ladders and aerial units will serve.

Remember, all ladders placed should remain there once positioned. Also place a secondary means of egress for safety. Remember to sound for the roof whether or not visibility is good; this can help to determine whether it is strong enough to support the weight of the ventilation group. In addition, when visibility is minimal, it may prevent a crew from taking a 10ft first step from off of a parapet wall. Perform a good roof recon to point out your secondary means of egress in case of emergency.

When performing ventilation on the roofs of multi-family structures or businesses, remember to work smarter not harder. If natural openings such as skylights or scuttle hatch access exist, utilize them for ventilation.  

  • Consider the use of vertical shafts for ventilation once checked. That section of the roof where smoke is showing should be the primary opening.
  • Once the roof has been ventilated, ventilate the top floor by what ever means available. If the top floor is charged with smoke, consider opening the windows from an aerial ladder or platform for safety.
  • Remember to thoroughly ventilate the floor directly over the fire when possible, and the fire floor itself must be ventilated to allow for rapid advancement of hose-lines and to assist with primary searches.
  • Adjoining buildings must be checked quickly for fire extension and ventilated when necessary. Again, consider the use of skylights, scuttles, and vertical shafts if available. Confirm that the cock-loft is ventilated when utilizing skylights or scuttles — some interior finishing processes may have completely enclosed the cock-loft. Ensure the "box" that is the cock-loft is opened and that it has a way to get rid of any smoke or fire that may be contained within it. Consider that fire in exposures should be ventilated with a roof opening over the hot spot.  

Shopping centers and strip malls
When fighting fires in shopping centers or strip malls, assume that there are no fire walls between stores or building sections — eventually your assumption will be correct. When ventilation is required, consider utilizing the roof first. This may be accomplished by utilizing existing construction features already on the roof, such as skylights or scuttles. Use these natural features only if they are close enough to be over or near the seat of the fire. If there are no natural construction features in good proximity, evaluate the necessity of cutting a ventilation hole over the seat of the fire. Ensure that the roof ventilation operations are large enough to operate effectively as there may not be any other means of ventilation, such as windows.  

  • Be aware of areas that may cause injuries such as parapet walls or marquees. Remember that direct flame contact on interior structural steel may push out walls or interrupt the structural support system for the roof.
  • Avoid areas of the roof where it is spongy or sagging.
  • In attached occupancies in strip malls, once the roof has been opened up attempt to utilize natural features for exposures. To do this, ensure you are aware of the direction the fire is moving and provide for a vent hole for accumulated fires gases. If fire is found in an adjoining occupancy, open the roof over that fire.
  • Window lights may significantly reduce the amount of effort required to ventilate occupancies, as well as the timely removal of front display windows along with rear doors and windows.

Basement fires in large structures
When ventilating for a fire in a basement in larger structures, remember that any opening into the basement can be effective. Where possible, utilize those openings that are not being utilized for fire attack. If there is only one entrance, evaluate the possibility of ventilating through basement windows. Basement fire ventilation through basement windows can be accomplished easily by removing the basement windows below ground level and removing grates if necessary. 

  • If the fire in the basement is not extinguished quickly, it may become necessary to cut a hole in the first floor just inside a front window to allow for effective ventilation of products from the basement fire. Once the floor cut is complete, open the first floor window to draw the products of fire to an expected path of egress.
  • If the store basement does not have basement windows or doors in front of the fire building, it may be necessary to open a hole from the basement just behind the front display window. Remember to remove the display window before creating the ventilation hole in the first floor to the basement. It may be necessary to remove basement ceilings to complete the process. If the store has multiple display windows, remove as many as are necessary to ensure good ventilation from the basement when coordinated fire attack operations are occurring.

Fire-resistant structures
Ventilation in fire-resistant structures offer a real challenge to a ventilation group. They cannot be ventilated in the same manner as standard structures. To accomplish ventilation, one must consider the use of windows, stairwells or smoke removal systems. A Smoke removal system is a nice tool to have if the fire crews are familiar with its operation and have practiced utilization. A good back-up for the smoke removal system is to have the building engineer on call to respond when needed to assist with controlling the ventilation of smoke from a fire-resistant structure. If you are dealing with structures built prior to smoke removal systems, you will have to ventilate in the tried and true manner.

  • Windows are the best method to ventilate fire-resistive structures. When possible, prop doors open and then remove/open as many windows as possible on both sides of hallway corridors.
  • Vent the fire floor primarily to assist with search and hose-line placement. Move on from there to vent the floor above the fire and search for victims. This procedure creates a need for hose-lines to be advanced to the floors above the fire to prevent vertical extension of the fire.

Another option for fire-resistive ventilation is the utilization of stairwells. This procedure works best if the structure has been vacated or is unoccupied. Open doors from the hallway corridors into the stairwell. This will allow for natural smoke movement into the stairwell and provide for vertical ventilation. The ventilation crew will have to provide for a ventilation opening at the top of the stairwell shaft. This manner will assist with removing the products of combustion to reduce the physical beating an attack crew will take when fighting fires in fire resistive structures.

This article has presented ideas for focusing ventilation concepts based on the structure involved. While I have attempted to present these from a global perspective, there is no way I have touched on the ventilation of every type of structure you may encounter. But the same basics of ventilation will work for every structure; the only difference is how you apply those basics to what you want to accomplish.

Remember that ventilation is not just a skill, it is a fine art. Those who are good at it are extremely valuable on every fireground. However, all of us has the responsibility to be competent enough to deliver this service when required. Practice your basics and apply them when pre-planning your buildings. Start building mental slides on how you would ventilate each structure you may be called on to fight a fire in within your district.

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