How Different Types of Construction Affect Roof Ventilation, by Firefighter Nation

We posted a series of articles a few months ago by Lt. John Hayowyk, Jr. of the Passaic, NJ Fire Department on how to access the roofs of Type 3 buildings during fires. That got us thinking: Just what is a “Type 3” building?

Capt. Randy Frassetto of the Surprise, AZ Fire-Medical Department has the answer over at Firefighter Nation. And since we sell roof ventilation blades, this article is about roof ventilation, too.

As you know, buildings can be grouped into five types based on their fire resistance. According to Frassetto, each type influences safe roof ventilation in surprising ways:

  • Type 1 (Fire-Resistive): Buildings of this type are made of fire-resistant materials like concrete and steel. They include high-rises and skyscrapers. They’re almost impossible to ventilate vertically or horizontally due to their height and heavy construction materials.
  • Type 2 (Non-Combustible): Buildings of this type are made of non-combustible materials like reinforced masonry and tilt slab. They include big box stores and strip malls. They often have metal roofs that are prone to early collapse and that resist most ventilation blades (but not the Fire Rescue Safety Blade).
  • Type 3 (Ordinary): Buildings of this type typically have non-combustible walls and wood roofs. They include a wide range of new and old construction. Vertical ventilation is often effective on Type 3 buildings, but their roofs and walls are sometimes unsafe for ventilation crews.
  • Type 4 (Heavy Timber): Buildings of this type are made of heavy, large-dimensional timber. They include many buildings built before 1960. These buildings normally resist fire well. However, their timbers may be poorly maintained or infested with termites, forcing roof ventilation crews to take extra care, and are heavy enough to slow cutting.
  • Type 5 (Wood-Framed): Buildings of this type are made of combustible materials like wood. They include many modern homes. They’re often roofed with ceramic or asphalt shingles over lightweight trusses or oriented strand board (OSB), materials that are easily cut by most roof ventilation blades. These buildings can collapse quickly, but they respond well to roof ventilation, especially over isolated room fires.

Read more at Firefighter Nation, and let us know what you think in the comments here.

Capt. Randy Frassetto, Firefighter Nation, “Understanding Building Construction Types

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