Uncategorized – AC INTERIOR GROUP



structures are high-rises, and they’re the stoutest of all construction types when exposed to fire. High-rises are usually defined as buildings more than 75 feet tall, with some agencies making amendments for buildings that are 35–55 feet tall.structures are constructed of concrete and protected steel (steel coated with a fire-resistant material, most often a concrete mixture), and are designed to hold fire for an extended amount of time in order to keep the fire at bay in the room and/or floor of origin. As far as the typical ventilation operation of getting on the roof and cutting a hole, that’s not really an option when dealing with Type 1 construction. Even horizontal ventilation becomes challenging, as the windows are thick, tempered glass and may not be an efficient way to ventilate the structure. Ladder companies must be aggressive in securing the stairwells for both firefighters and victims evacuating the structureLadder companies must be aggressive in securing the stairwells for both firefighters and victims evacuating the structure. If the structure meets building code, it will be equipped with self-pressurizing stairwells and have HVAC systems that will aid in air movement. If necessary, the ladder company may need to mechanically pressurize the stairwells using a series of fans strategically placed at the base of the stairwell and every 10–12 floors depending on the effectiveness of the fans. The fire protection and fire-related systems in these buildings are overwhelming, so crews should make it a priority to locate a maintenance worker and keep them close throughout the incident.

Heavy Timber

construction is found in older buildings and utilizes large dimensional lumber for structural members and interior elements. These buildings hold up well under fire conditions, but it’s critical that firefighters not feel a false sense of security, as these buildings are often poorly maintained, or have termites and/or weathering issues that can contribute to an earlier-than-expected collapse. Firefighters can identify these buildings by the large lumber used for walls and the long distance of roof spans. These buildings were most commonly built before 1960, when bolts and metal plates were used as connectors. Vertical ventilation may be achieved on these buildings, but sawyers may encounter thicker-than-expected decking that may make for a longer completion of a ventilation hole.


construction is found in many modern homes. The walls and roofs are made of combustible materials—most commonly wood. If the walls are wood-framed, the roof usually is as well. Rooftops are ceramic tile or asphalt shingles placed over lightweight trusses and OSB. Both UL and NIST studies have found that lightweight construction will fail within minutes of direct fire impingement. Firefighters should sound the walls prior to going to the rooftop. Whether operating on tile or asphalt rooftops, alternatives to rooftop ventilation should be considered if there is heavy attic involvement. If fire is isolated to a room, flashover (not collapse) is the main concern, and aggressive ventilation is beneficial. Because the roofs are made of wood, ventilation can occur through the asphalt shingles, but tiles should be removed first if encountered. Positive-pressure attack is another tool that may prove beneficial for Type 5 construction.
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