T3 Training: Building Construction
 
By East Brandywine Fire Company
July 6, 2017
 

On Wednesday evening July 5th, East Brandywine Fire Company volunteers reviewed lightweight building construction. FF Ed Skrzat provided participants with an overview of all aspects of lightweight building construction and their associated hazards. Ed is an expert in this area as a former Deputy Chief of the Fire Department of Montgomery Township and Vice President of FM Global.

East Brandywine Township is the second fastest growing Township in the State of Pennsylvania so development is on-going. Provided the growth it is essential for volunteers to be educated and trained on the hazards associated with this type of construction. It is also important so that Officers can better direct personnel at a scene with regard to fire growth and spread.

Jeremy Smelcer from University of Cincinnati describes lightweight construction as follows:

The construction industry began using pre-manufactured components and lightweight construction methods in order to improve the efficiency of the construction process and in order to reduce costs associated with materials.

These members include pre-manufactured I-beams and I-joist, truss systems, and plywood and OSB boards. I-beams and joist are manufactured by placing a plywood or particle board sheet in between two 2x3 or 2x4 boards that form the top and bottom chords. If one of these chords fails because of charring from impinging heat and fire that the joist loses its structural strength to support a load.

Truss structural members use a system of triangles along a plain to give strength to support the forces that are applied to the members. Truss systems give strength along long spans and are considerably lighter than the comparable beams that it would take to span the same area. The problem that arises with truss systems is that if the top or bottom chord of the truss fails than the entire truss fails, causing the supported floor or roof to collapse.

Plywood is composed of thin layers of wood that are glued together to form a panel. OSB is composed small strips of shredded wood that is joined together by compressing the wood and heating the resin that coats the wood until it cures into a single panel. These members are very cost effective and allow for precise engineering that give exceptional strength under normal conditions. Under fire and heat conditions however, these component will fail due to the thinness of their members, the glue and resins that are used to compose them and because of the metal components that are used to join them.

Metal gusset plates are often used to join members in truss systems. These gusset plates are thin pieces of metal with small teeth that hold the wood members together. Many of these gusset plates are designed with teeth that only penetrate 0.38 inch into the wood that they hold together. These plates will also fail to hold if the wood behind them is charred away by impinging fire.

Another issue that increases the chances for these members to fail is the increased heat release rates of the items and materials found in residential properties. The problem that firefighters face is one that has been prevalent over the past thirty years.

The Line Officers of East Brandywine Fire Company would like to thank FF Skrzat for his informative training session.

 
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