FSTA, Building Construction Related to the Fire Service Chapter 11 questions and answers

Roof A waterproof cover of a building, can block streams from ladder pipes and platform apparatus from penetrating the fire Roof considerations -Roofs are typically not as strong as floors -Many types of roofs have inherent concealed spaces -Roofs may have loads added that they were not originally designed to support -Subject to wear and tear from the elements Flat roofs Found on buildings of all types such as large area warehouses, shopping centers, schools and may have slight slope to facilitate drainage Pitched roofs: Designed to shed rain and snow, can be increasingly hazardous when wet or covered in ice Low slope roofs: 3 over 12 (rise over run) or less Medium to high slope roofs: 4 over 12 to 12 over 12 (rise over run) Shed roofs Roof that slopes only in one direction Gable roofs Two inclined surfaces that meet at their high side forming a ridge Hip roofs Slopes in four directions, slope similar to a gable roof Gambrel roofs Slope in two directions, but there will be a break in the slope on each side, can use space underneath for attic or living space Mansard roofs Break in slope on all four sides, modern mansard can have a flat deck constructed on top, firefighters must be cautious when working on theses roofs because they can collapse in large sections Butterfly roof Slopes negatively inward, two shed roofs that meet at the lower eaves Monitor roof Style designed to provide light and ventilation, raised central section of roof extends several feet above the surrounding roof surface, vertical sides of monitor section called clerestories Sawtooth roofs Used in industrial buildings for light and ventilation, can have north-facing vertical glass sections Curved roofs Often constructed as a series of half arches that connect at a central point, top point of a dome roof is called a keystone Keystone Top point of a dome roof Lamella Arch Arched roof structure composed of a series of intersecting, skewed arches, made up of relatively short, straight members, members are bolted, riveted or welded at point of crossing. Most commonly made of wood and vary in thickness from 2x8 inches to 3x16 inches with lengths varying from 8 to 14 ft Lamella washer Special plate used to secure lamellas together in a diagonal pattern Lamella arch occupancies Gymnasiums, exhibitory halls, and auditoriums Geodesic domes Created using spherical triangulation, can be constructed out of materials such as wood, steel, concrete, plywood, bamboo, aluminum Dormers Used in buildings with pitched roofs to increase available living space in an attic, can be gable, hip, mansard deck, flat, or shed roof construction Joists Horizontal structural members used to support a ceiling or floor, drywall and a subfloor can be secured to ceiling or floor joists Flat roof considerations -Flat roof support can be supported with open-web steel joists and steel beams or more commonly wood joists -Flat roofs usually must be designed to support the weight of a least a few workers so they can be accessed for maintenance Inverted Truss Truss support system that is constructed with a deep triangular portion projecting down instead of up, portions of the standard truss are under compression not tension Conventionally Framed Roofs Roofing system constructed on-site, often uses dimensional lumber, nails, screws, can have prefabricated components Rafter Inclined beam that supports a room, runs parallel to the slope of the roof and the roof decking it is attached to Ridge Board Highest horizontal member in a pitched roof to which the upper ends of the rafters attach Collar Tie Horizontal roof framing member in the top third of the framing system, braces roof framing against the uplift of wind Rafter Tie Horizontal roof framing member at the bottom of the roof framing system, helps keep walls from spreading due to the weight of the roof Conventional framing roof types - Shed - Gable - Hip - Gambrel - Mansard Ceiling (Attic) joists Used to resist the outward thrust of rafters Structural ridge beam Used to support rafters if the underside of the roof is exposed Common Truss Truss structure with the chords and diagonal members arranged in parallel planes, aka monoplane truss Truss considerations -Trusses have a reduced mass in comparison to beams and joists, due to their interdependence amongst components they are vulnerable to early failure in fire conditions -Failure of any single element of a bowstring truss will lead to catastrophic failure of the system Rolling Roofing Roof covering made of flexible material that may be applied to the roof deck as a continuous sheet, commonly used on shallow pitch roofs Purlin Horizontal member between trusses that support the roof Roof decks Serve to separate the structure from the effect of weather and supporting the materials used to perform this application Roof deck materials - Plywood - Wood planks - Corrugated steel - Precast gypsum or concrete planks - Poured gypsum - Poured concrete - Cement planks containing wood fiber Nailability Property of a material that allows it to accept a fastener, include wood, gypsum, and some metals Roof covering factors - Maintenance requirements - Durability - Wind resistance - Fire resistance - Hail and snow - Possibility of corrosion from fog, salty air, smoke, or other pollutants - Drastic changes in temperature with the seasons