Why did the Firefighters cut holes in the roof?
Recently, The City of Hudson Fire Dept was requested to Hillsdale and Claverack with our Tower Ladder Truck to assist with opening the roofs of their respective structure fires. Several people have asked why we do that and what purpose it serves?
Firefighters may cut holes in the roof for a variety of reasons. Two of the most common reasons are to release trapped smoke and heat “A Vent Hole” or to stop fire from spreading “A Trench Cut”.
In Hillsdale the crew executed a trench cut to stop the fire flow from continuing to spread thru the common attic space. The trench cut or "strip ventilation" is a long narrow ventilation hole that acts as a fire break on the roof of a structure that is being attacked by the fire. This tactic is used when confronted with a stubborn concealed fire that is difficult to reach, or a fire that has a stronghold on the attic or cockloft space of a long, narrow building. It can also be used for a top floor fire within a building with a choke point in the roofline where a trench can be cut. The main focus of this defensive tactic is to cut off fire extension to an area of the building that has not been involved in fire. The defensive posture of saving a portion of the building may result in writing off a section of the structure. The manpower and equipment needs of this tactic will require the progressive Incident Commander (Fire Chief) to call for multiple alarm companies early in the incident so they are on-hand to be deployed early in the fire. Delaying the start of this tactic will increase the loss of the property, to a potential level that the entire structure may be a total loss.
In Claverack the crew executed a vertical vent hole cut by cutting a rectangle hole thru the roof. Vertical ventilation is a quick method for the removal of hot gases and smoke from the upper portions of a structure. Seeing as heat rises naturally, all of the smoke and hot gases will be travelling to the highest point within the structure as it starts to mushroom back down. By alleviating the smoke and hot gases through a vertical opening, we are allowing for the increase in visibility and decrease in temperatures inside the structure, making it easier for the fire attack crew to make a fast and efficient extinguishment of the fire ultimately decreasing the amount of smoke, fire and water damage in the structure in turn causing far less damage than was caused by cutting a hole in the roof. This tactic may also increase the likelihood of the survival of trapped victims by making conditions more tenable for the victim and allowing the search crews better visibility to execute a rescue. Vertical ventilation is an offensive coordinated strategy with considerations to the location and size of the vent hole, fire location and conditions and coordination with the fire attack crew.
Fire Engineering: Truck Company Ops: Vertical Ventilation By Mark van der Feyst | 5.3.2018
Firehouse: The Trench Cut - When, Where and How By Michael Daley 10.14.2011