Firehouse

JAN 2017

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Attic fires are difficult to extinguish for several reasons, the most important one being access. The opening to an attic is limited. Access could be a pull-down ladder in a closet ceiling or a narrow stair. Another challenge in an attic fire is smoke removal. Venting is difficult because there may be only one small attic window or it may be completely sealed. An attic may also contain the largest amout of combustibles inside the build- ing. Further, even if an attic is empty, there is a lot of exposed wood, such as the underside of the roof deck, roof raf- ters, the ridge beam and unfinished wood beams and flooring. To prevent a lower-floor fire from spreading to the attic, firefighters must be aware of the concealed spaces that lead to an attic from the lower floors, and they must check these spaces as soon as the downstairs fire is extinguished. For exam- ple, any fire in a top-floor bedroom that extends to the ceiling will likely spread to the attic directly above. Also, if the house is balloon-frame construction, there can be direct openings, spaces between exterior wall studs that extend from the cellar to the attic space. Therefore, it should be assumed that any fire in a cellar can quickly spread up to the attic space. And it's not only the exterior wall; if there's a room or section of housing added to the building, an exterior wall can become an interior wall. Another avenue of fire spread to an attic can be the absence of attic flooring behind an attic knee wall. During any dwelling fire, an incident commander (IC) must constantly ask him- or herself, "Has this fire spread to the attic?" And as soon as the main fire is knocked down, they must give the order to have someone check the attic. Knee wall An unfinished attic in a home with a slop- ing peaked roof will, naturally, create a triangle-shaped space. A homeowner may decide to finish an attic by putting sheet rock on the underside of the roof and walls to make it a livable space. Part of this will include knee walls, which are typically knee-high partitions that conceal the areas of the attic where the sloping roof rafters meet the floor. A 3- to 6-foot-high knee wall under sloping rafters creates a concealed space that must be opened during a fire and checked for fire spread. If fire spreads to an attic, it is most likely behind the knee walls. When an IC says "check the attic," that means the concealed spaces behind the knee walls must be opened up. Firefighters must exercise caution when opening and checking a knee wall space. This space can contain built-up superheated smoke and fire that can suddenly erupt and quickly fill an attic space. Firefighters open- ing up knee walls in attics have been sud- denly engulfed in smoke, disoriented and trapped. Before a knee wall is opened, fire- fighters should first size up the attic and determine an escape path. Purlins and collar beams Two seldom seen building construction members—purlins and collar beams—are often found in attics. These wood mem- bers are used in peaked roof construction. Request information at Firehouse.com e-inquiry January 2017 l Firehouse l 21

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