Fire Prevention & Protection, Firefighting

Reading A Building – The Age Of A Building

By John W. Mittendorf

During the course of this series, we have considered construction, roofs, style, and method. Let’s continue with the age of a building. For size up purposes, buildings can be conveniently divided into three general classifications as follows:

  • Pre-1935
  • 1935 to 1960
  • Post 1960

Pre-1935 Buildings
Buildings constructed prior to 1935 (remember the Long Beach earthquake?), generally featured, unreinforced masonry (URM) construction, heavy trusses, a heavy style of construction and were built using marginal building codes. Reading A Building – Unreinforced Masonry Construction and Reading A Building – Identifying Unreinforced Masonry Construction covered URM construction and why it is a prime candidate for collapse. Although “a truss is a truss”, the truss construction of pre-1935 buildings used significantly larger components than the trusses of today. Therefore, the heavy truss of yesterday is capable of providing more fireground time (before collapse) than the modern 2 x 4-inch truss. Also, the construction components of pre-1935 buildings (residential and/or commercial) was larger than those of modern times. As an example, a pre-1935 2 x 4 was two inches x four inches and lumber was often “rough cut” and full size. That is not true today. Modern 2 x 4s are 1.5 inches x 3.5 inches. What this means is that although URM construction can be dangerous and building codes were often minimal and/or circumvented, the normal size of pre-1935 lumber can allow more fireground time than today’s lumber.

1935 to 1960
This time frame is characterized by improved building codes, conventional building methods, and decent building materials. From a fireground perspective, this was the best time frame for building construction. Buildings featured minimal surprises and used a standardized approach to building construction. As an example, builders didn’t employ URM construction, lumber was still generally “full size”, lightweight trusses were still a “gleam” in the eyes of the building industry, and synthetic materials were not as common as today. These factors combined to produce a fireground that offered enhanced fireground time as compared to the modern fireground, and with minimal surprises.

From 1960 to present, although it is common to find strict building codes, you will also find lightweight trusses, alternative building methods, and last but not least synthetic materials in residential and commercial buildings. Lightweight trusses should not surprise any firefighter as they have been used since the 1960s in residential construction, and a growing number of commercial applications. Alternative building methods have yielded an interesting array of products (i.e., ABS plumbing, “tin can studs”, foam and membrane roofs, vinyl siding, curtain construction, and so on). One of the most dangerous factors influencing the modern fireground is the widespread use of synthetic materials, which can result in fires that burn two to three time hotter and faster. In fact, unlike 30 years ago when it was virtually nonexistant, flashover is now a common fireground problem. So, when we summarize the age of a building (based on the history of building construction), we can safely assume that what firefighters encounter today will be significantly different than what they encounter 10 years from now – and guaranteed, it will not be to the benefit of firefighters.

When you drive through your district, look at your fireground office and analyze your buildings from an age and hazard/strength perspective.

John W. Mittendorf joined the Los Angeles City (CA) Fire Department (LAFD) in 1963, rising to the rank of captain II, task force commander. In 1981, he was promoted to battalion chief and in the year following became the commander of the In-Service Training Section. In 1993, he retired from LAFD after 30 years of service. Mittendorf has been a member of the National Fire Protection Research Foundation on Engineered Lightweight Construction Technical Advisory Committee. He has provided training programs for the National Fire Academy in Emmitsburg, Maryland; the University of California at Los Angeles; and the British Fire Academy at Morton-in-Marsh, England. He is a member of the editorial advisory board of Fire Engineering and author of the books Truck Company Operations (Fire Engineering, 1998) and Facing the Promotional Interview (Fire Engineering, 2003).