The allowable area per story can exceed allowable fire areas and a sprinkler system may be required. If sprinklers are provided, allowable area increases for both sprinklers and open frontage may be taken. For several occupancies covered in this book, the requirement for sprinklers can also be triggered by specific use, height above grade or occupant load. Sprinklers offer a substantial increase to life safety, which is well documented and merits the consideration of designers for that reason alone.
But their advantages can also be economic. For these reasons, the addition of sprinklers should always be considered in the overall cost analysis for any project. Total Building Area Limit Single Occupancy A single occupancy building with three or more stories above grade has a total building area of the allowable building area per story Aa multiplied by three in accordance with Section Therefore, buildings with four or more stories of the same floor area will have smaller maximum areas per floor than a three-story building of the same type of construction and occupancy.
For two-story buildings, the total building area is the maximum allowable building area multiplied by two. The maximum area of any story above grade cannot exceed the allowable building area per story. A single basement is not included in the total allowable building area in accordance with Section The actual building area for all stories added together must be less than the total allowable building area.
The maximum allowable building area for residential buildings provided throughout with an NFPA 13R-compliant automatic sprinkler system is determined by multiplying the allowable building area per story Aa , as determined in Section A building area increase can only be applied due to the frontage calculations.
The building height increase for Group R structures still applies in accordance with Section But, a single-story basement does not need to be included in the total allowable building area, when the basement does not exceed the area permitted for a single story. More than one occupancy in a single building can be accommodated by using the allowable area of the most restrictive occupancy referred to as "nonseparated occupancies" in accordance with Section Alternatively, the occupancies can be regulated as a "separated occupancies" Section The code also accommodates limited area spaces that are accessory to the function of the main occupancy, if the restrictions of Section See Section The tables at the end of this book illustrate the allowable area and height increases permitted for individual occupancies.
Tables 1, 3, 5, 7, 11 and 16 list allowable nonsprinklered building area per story for each occupancy. Tables 2, 4, 6, 8, 9, 10, 12, 13, 14, 15 and 17 list allowable sprinklered building area per story for each occupancy. Unlimited Area Buildings One-Story Buildings—Sprinklered The following unlimited area buildings with a single story above grade plane are permitted if the building is equipped throughout with an NFPA compliant automatic sprinkler system and surrounded on all sides by public ways or yards not less than 60 feet wide.
The open frontage can be reduced in some circumstances Section Unlimited area Group B, F, M and S buildings of any construction type are also permitted with no special restrictions in Section For indoor activities such as tennis, swimming, skating and equestrian venues, the sprinkler system is not required if exit doors lead directly outside from participant areas and a fire alarm system with manual fire alarm boxes is installed as required by Section Unlimited area Group E buildings are permitted by Section Unlimited area Group A-3 buildings of Type III or IV construction, used as a place of religious worship, community hall, dance hall, exhibition hall, gymnasium, lecture hall, indoor swimming pool or tennis court, are permitted by Section Section There must be at least 40 feet provided and the exterior wall and all openings on those portions will require 3-hour minimum fire-resistance and fire protection ratings.
Allowable Increases with Fire Walls A fire wall is a fire-resistance-rated wall with protected openings that restricts the spread of fire and extends continuously from the foundation to or through the roof. Fire walls built in compliance with Section create separate buildings for the purpose of area limitations and other code-required features. Fire walls separating F-1, S-1 and M occupancies require a 3-hour minimum fire-resistance rating while F-2, S-2, R-3 and R-4 occupancies require a 2-hour minimum fire-resistance rating.
Each portion of a building separated by a fire wall is evaluated individually for allowable heights and areas based on the type of construction. Fire walls in Type V construction may be wood frame; in other construction types they must be of noncombustible materials in accordance with Section Special Provisions for Stacked Buildings Under specific circumstances, buildings of different types of construction are allowed to be built on top of each other and are commonly referred to as pedestal buildings.
They are only permitted when following the provisions of Section Two subsections recognize wood construction. The lower building is limited to one story above grade plane and must be Type IA construction. Group B, M and R occupancies and Group S-2 open and enclosed parking garages are permitted in either building, subject to the building height and area limitations discussed previously. Multiple Group A occupancies, each with an occupant load of less than , are also permitted in either building.
Group S occupancies other than parking garages are permitted only in the upper building. American Wood Council International Code Council Code Conforming Wood Design 15 Type IIIA construction in Groups R-1 and R-2 may be increased above the general limitations of Sections and to six stories and 75 feet where the first floor assembly has a fire-resistance rating of not less than 3 hours and the floor area is subdivided by 2-hour fire-resistance-rated fire walls into areas of not more than 3, square feet as provided by Section For Group R occupancies, the number of stories of a building with a single-story Group S-2 parking garage of Type I construction or open parking garage of Type IV construction, with grade entrance, are permitted by Section The floor assembly between the parking garage and the Group R above must be the type of construction required for the parking garage, must provide a fire-resistance rating in accordance with Table The upper building height and area are limited as previously discussed and the open parking garage is regulated in Section The height of the upper building is measured from the grade plane and includes the open parking garage level.
Multiple upper buildings may be positioned on a single parking structure complying with Section Lastly, Group S-2 open parking garages above a first-story occupancy of Group B or M are allowed in accordance with Section Establishing Fire Resistance Table establishes the required fire resistance of building elements primarily the structural frame, walls, floors and roofs due to the construction type of the building e.
Required ratings are given in hours. The exception is Type IV, where the wood structural elements are assumed to have inherent fire resistance due to their required minimum dimensions no fire-resistance rating is required except for exterior walls. Fire resistance describes the rate at which a building material degrades due to a fire.
Resistance is based on how fast a material will burn, how rapidly the strength of the member or assembly is affected by the fire and whether the member or assembly can maintain its design strength. Fire resistance of wood members and assemblies may be established by any one of five means listed in Section The most common methods are indicated below.
Using one of these standards, an assembly is typically assigned a 1- or 2-hour fire rating depending on its performance in the fire test s. Although Section The fire resistance of wood frame assemblies also may be calculated using the provisions of Section It is available at for free download at www. Section specifies 25 applications where combustible materials are permitted without reclassifying the building to a different type of construction.
For example, wood blocking is permitted for handrails, millwork, cabinets and window and door frames. Show windows, wooden bulkheads below the window and nailing and furring strips are also permitted to be wood if the window is not more than 15 feet above grade. FRTW is permitted in nonbearing partitions where the fire-resistance rating does not exceed 2 hours, and may be used in nonbearing exterior walls that do not require a fire-resistance rating.
Roof construction, including structural framework, permits FRTW, except for Type IA construction of three stories or more where the lowest roof member is less than 20 feet measured vertically from the upper floor.
Because of this, certain code provisions American Wood Council International Code Council Code Conforming Wood Design 17 that assume noncombustible exterior walls have become difficult to interpret. But usually a practical solution to these code questions can be achieved by working closely with the code official. For instance, the addition of solid FRTW wood blocking of a certain thickness in floor cavities that intersect with the exterior wall in Type III construction is an appropriate precaution to maintain the fire resistance and material integrity of the exterior wall.
Heavy Timber Members Heavy timber HT construction is permitted in roof construction as an alternative to 1-hour or less fire-resistance-rated noncombustible construction. HT columns and arches are permitted on the exterior of walls if the fire separation distance is 20 feet or more. Wood Features Figure Heavy Timber Construction Wood may be used as an architectural or structural component of a building. It is renewable and biodegradable, using less energy to manufacture than steel, concrete, aluminum or plastic.
Wood use in foundations, doors, windows, exterior and interior finishes, trim and roofing contributes to the aesthetics of the building in an economical and efficient manner. Insulated wood foundation systems conserve energy and easily accommodate installation of wiring, plumbing, ductwork and interior finishes. Savings in labor, time and material costs may be achieved when these systems are used.
Wood Walls and Partitions Wood stud framing is permitted for all load-bearing and nonload-bearing interior walls and partitions in Type III and V construction. Type IV construction permits wood stud framed partitions of 1-hour fire-resistance-rated construction Section In Type I and II construction, partitions dividing single tenant offices or retail and not creating corridors serving 30 or more occupants are permitted to be FRTW, 1-hour fire-resistance-rated construction or of wood panels or similar light construction up to 6 feet in height.
Table All classifications must have a smoke-develFigure Wood Interior Finish oped index between Section Photo Courtesy of Barbara J Sales Nonsprinklered buildings typically require more restricted flame spread materials than sprinklered buildings. Figure 18 contains two tables outlining the required interior finish minimum classification for exit enclosures and passageways, corridors and enclosed spaces and rooms. This simplified table is not comprehensive; more exceptions can be found in Table Buildings less than three stories above grade plane permit the reduction of the exit enclosure and exit passageway classifications to Class B.
Exit enclosures and exit passageways are permitted to use Class C wainscotting or paneling in the grade lobby for not more than 1, square feet of applied surface when applied to a noncombustible base. Lobby areas in corridors may use Class B interior finishes for Group A occupancies. Buildings less than three stories above grade plane permit the reduction of the exit enclosure and exit passageway classifications to Class C. Figure Summary of Table Save my name, email, and website in this browser for the next time I comment.
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Mike M. Convenience Is Key No longer am I searching the web for the right resource, files. Identify IBC requirements for fire precautions during construction. Apply IBC provisions for the use of wood in finishes and trim; in building appendages such as balconies; in noncombustible construction types; and in other building features. Locate the fundamental IBC structural provisions for wood design and identify the IBC-referenced wood design standards.
Click here for Stand-Alone Link. Free Download. Perforated shear walls and the basis for conventional construction are featured. The document notes where significant provisions of the IBC are identical or similar to those of the UBC; and where provisions are significantly different, a comparison is provided. To assist the reader in applying the information provided in the brochure to the actual text of the code, various sections of this brochure are titled to correspond with the code chapters to which they apply.
Chapter subject matter and number in the IBC are the same as in the UBC since both are based on the common code format utilized by the three model code organizations. Although most of the information contained herein pertains to IBC provisions which specifically address wood and wood construction, some of what is discussed has general application.
The reader is urged to always consult the current edition of the code and the authority having jurisdiction for local amendments.
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