Vertical Ventilation: Elevation

• Firefighters use vertical ventilation techniques to cut vents and make use of existing openings on the roof of a burning structure to allow heat and smoke to travel upward and escape. The first disadvantage of vertical ventilation is that firefighters become subjected to the risks associated with being in elevated structures. As firefighters climb up and work on a particular height, they put themselves at the risk of falling. As fire begins to weaken roof structures, they can begin to collapse and a firefighter can also fall through if the structure he is stepping on collapses. Not all roofs have a level surface, which can cause disorientation, a fact that could delay or even endanger a firefighter.
  
  

Vertical Ventilation: Expense

• Vertical ventilation is a costly method. Minimum requirements include two trained firefighters with full protective gear, a set of tools for making vents and a charged hose line. Because it requires a lot of resources, there are firefighting units that just don't have the proper resources to conduct vertical ventilation.
  
  

Vertical Ventilation: Time Consuming

• Vertical ventilation is a time consuming process. There are many roofs that are difficult to reach. It takes time to set up a ladder or an elevated work platform. Climbing up toward the roof itself eats up time. If the fire is not on the top floor of a building, there is little benefit from vertical ventilation and the effort would be wasted.
  
  

Horizontal Ventilation: "Mushrooming"

• Horizontal ventilation techniques allow heat and gases to travel laterally out of a structure. Horizontal ventilation usually requires breaking windows and opening doors. Hot gases and smoke tend to move upward; even if heat and smoke are allowed to escape from the windows, doors and other openings of the burning building, they can still mushroom within. This makes horizontal ventilation a less effective method of ventilation.
  
  

Horizontal Ventilation: Wind

• Another disadvantage of horizontal ventilation is that it can negatively influence the outcome of fire control if heavy winds are present. Heavy winds carry oxygen, a gas that can effectively facilitate the burning process. Too many vents would then allow heavy winds to feed the flames instead of controlling them. Firefighters must take care in placing vents in order to minimize the effects of heavy winds, i.e., on the side of the structure facing the direction of the wind and not the side that faces where the wind is coming from.