Fire Resistance Ratings

Fire-Resistant Metal: Understanding Ratings for Safer Building Design

Steve Gaynor of RAiNA and PIVOTH, shared important information about the exterior wall assembly fire performance code on a free METALCON Online Webinar on-demand below. In addition to understanding the exterior wall assembly, knowledge about construction types is vital for firefighters and anyone in the construction industry. Thanks to BigRentz, here’s a look at the five building construction types and their respective fire resistance ratings.

At the IBHS facility in South Carolina, Daniel Gorham and his colleagues test building materials in a wildfire simulation. Engineers designed and built a full-size duplex home. On one side, the house has cedar siding, vinyl gutters, single-pane windows and bark mulch around the foundation. On the other side, the house is designed to be fire-resistant, with cement siding, metal gutters, double-pane windows and gravel around the foundation.
Credit: Insurance Institute for Business & Home Safety

Building codes classify all structures from Type 1 to Type 5, and this building type reveals crucial information such as fire resistance. The most fire-resistant buildings, Type 1 structures, are constructed with concrete and protected steel (Check out the 4 different types of steel HERE), which can withstand high temperatures without collapsing. By contrast, Type 5 structures, the least fire-resistant, are lightweight and made of combustible materials that collapse soon after catching fire.

Five construction types:

  • Type 1: Fire-resistive: High-rise buildings made of concrete and protected steel; generally, these buildings are more than 75 feet tall and are considered the safest in case of a fire, as they are able to withstand high temperatures for long periods of time.
  • Type 2: Non-combustible: Newer buildings or recently renovated commercial structures — including big-box stores and large shopping malls — with tilt-slab or reinforced masonry walls and a metal roof; while these buildings generally have fire suppression systems, they are prone to collapse when flames expose their metal roofs to high temperatures.
  • Type 3: Ordinary: New or old buildings with non-combustible walls but a wood-framed roof (eg, schools, businesses, homes); while these buildings contain some materials resistant to fire, their roof systems quickly burn and their fire-cut joists pose hazards to firefighters.
  • Type 4: Heavy Timber: Older buildings made from thick lumber; buildings are typically constructed before the 1960s using large pieces of lumber seen on barns, factories and old churches.
  • Type 5: Wood-framed: Modern buildings with combustible framing and roofs; many modern homes fall into this type due to their use of combustible materials — usually wood — in the walls and roof. Unlike the lumber in Type 4 buildings, Type 5 structures use lightweight or manufactured wood. While this material is inexpensive, efficient and structurally sound, it is not fire-resistant and these buildings can collapse minutes after a fire starts.

Knowledge about construction types is vital for firefighters and anyone in the construction industry. Understanding these construction types gives any construction worker or firefighter baseline knowledge about how these structures come together. 

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