Even when a building and its additions are familiar to us, we do not always remember the details of its construction at the time of a fire, structural collapse, or other serious incident. We usually assume that the entire structure will react to these conditions as a unit, and this error can lead us into difficult situations. A building and its additions are unlikely to react as a unit to fire or collapse, especially if there was a significant amount of time between the construction of the original building and its additions. The reasons for this is changes in construction materials and methods; a difference in the type of construction; and the addition of concealed spaces that may be combustible and will act as channels for the movement of products of combustion.
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- According to building and fire codes, what type of construction is the original building?
- Was the original building constructed according to the codes in effect at the time, or was it built before the codes for that type of construction were developed?
- Is the original structure sound, or does it contain structural defects like deteriorated foundations or load-bearing masonry walls; rotted wood beams, joists, or floors; or wall openings with inadequate arches or lintels to support the wall above?
- Is the original building still used for the purpose for which it was built, or has its occupancy classification changed?
- To what extent has the original building been remodeled, including the construction of new concealed spaces and the addition of new dropped ceilings?
- According to building and fire codes, what are the types of construction of the additions?
- Were the additions constructed according to the codes in effect at the time, or were they built before the codes were developed? Or were the additions built by the owner or occupant without professional design, plan review, and construction inspection by a building code official?
- How are the additions connected to the original building? Are the additions completely self-supporting, with columns and girders supporting the roofs at the face of the original building wall and connection to the original building wall only by the roof flashing? Or are the roofs of the additions supported by a ledger board or steel channel bolted into the original building wall?
- If the roof supports for the additions are attached to the original building wall, how sound are the connections, and have they deteriorated since they were installed?
- Are the additions still used for the purpose for which they were built, or has their occupancy classification changed?
- Were the supports for the roof-top air-conditioners and kitchen range hood exhaust equipment part of the design for the building addition, or were they added to an existing roof? If they were added, were additional structural supports installed to carry the added load?
Detailed size-up on arrival at an unfamiliar building and continuous size-up by everyone at the incident can point out many of these signs of potential problems. Communicating this information to the incident commander will enable him to make informed decisions on tactics and strategy based on knowledge of the building, its characteristics, and its anticipated fire behavior.
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