Building Codes and Ordinances ARC 227 Week 6 Fire Resistive Construction 03.02.10 Instructor: Rick Staub, AIA Email: staub@pointonearchitects.com Phone: 860-434-7707
Fire Resistive Construction Passive Fire Resistance passive protection is built into the building structure and provides a barrier between the structure and the fire. Active Fire Resistance active protection (fire sprinklers) respond to fire by activation of systems to contain or suppress fire and smoke to allow the structure to remain intact for a longer period of time than without protection while allowing occupants to escape Chapter 7 deals with passive fire protection Chapter 9 with active Two primary functions of Fire Resistive Construction First protection of the building structure, such protection is typically applied to the building structural members Second separation of spaces to prevent the spread of fire or smoke within a building and the spread of fire between buildings. The protection of spaces addresses fire or smoke impacts on larger scale building systems like such as floors, walls and ceilings as well as openings within these systems. Fire Area is defined as the aggregate floor area enclosed and bounded by fire walls, exterior walls and floors/roofs.
Fire Resistive Construction Trade-Offs between active and passive protection The code allows trade-offs between provisions of active versus passive fire protection for example 1-hour structural protection requirements can be offset by provision of sprinklers for certain occupancies. where active systems are required by code in relationship for given criteria, such as heights and area limits, then the provision of the active systems in lieu of passive is generally not allowed. Trade-offs imply a voluntary selection by the designer of how to provide the required degree of fire resistance. When code provisions otherwise require active systems they are thus not available to offset passive requirements
Fire Resistive Construction Fire Resistive Ratings Section 702 defines the fire-resistance rating as the period of time that a building element, component or assembly maintains the ability to confine a fire, continues to perform a given structural function, or both as determined by tests or methods described in section 703 The rating is given in hours Components, materials and assemblies are tested in a controlled environment to replicate real fire situations. ASTM American Society of Testing and Materials Test E 119 Section 703.3 allows designers to use several alternative methods to show compliance with fireresistive criteria. Use ratings as recognized by Underwriters Laboratory - UL Section 720 and Table 720 shows prescriptive assemblies and their various ratings. Section 721 lets you calculate your own ratings based on formula for various materials.
Fire Resistive Construction Exterior Walls Section 704 Projections - Section 704.2 governs the extent of allowable projections according o their relationship to the property line. projections include such elements as eave overhangs, cornices and balconies that extend beyond the floor area. projections are limited in two ways: -1/3 the length of the required fire-separation distance can project toward the property line - 12 max. projection into the area The combustibility of a projection is the same as required by the wall rating Multiple Buildings Section 704.3 When two or more buildings are on a site it is assumed that an imaginary line is drawn between Refer to table 601 and 602 for required ratings. Courtyard buildings more than one-story are treated the same way, an imaginary property line must be drawn and ratings applied per the Tables. the imaginary lines do not need to be equal. Section 704.5 Explains that buildings greater than 5 from the property line can assume that danger of fire is from the inside only. Buildings less than 5 from the property line assume fire danger from both sides and therefore ratings apply to both side of the exterior wall.
Fire Resistive Construction Exterior Walls, cont. Section 704 Openings - Section 704.7 and 704.8 Review table 704.8 Vertical separation of openings Section 704.9 Vertical exposure Section 704.10 requires protection of openings in any wall that extends above an adjacent roof. Less than 15 vertically above the roof of an adjacent building on the same lot need to be protected Parapets Section 704.11 makes a general statement that parapets shall be provided at exterior walls of a building. The purpose is to impede the spread of fire from one building to another. Exceptions reduce or eliminate need for a parapet. Typically need to extend 30 above the adjacent roof. No openings (skylights, hatches) with 5 of roof edge in R + M; 10 for others Summary: 1. the wall satisfies the fire-separation distance criteria per table 602 2. the building area is less than 1,000 s.f. on any floor 3. the roof construction is entirely non-combustible or of at least 2-hour construction 4. the roof framing construction is protected from fire from the inside 5. for residential a fire-barrier is provided by sheathing the underside of the roof framing or the roof sheathing is non-combustible for 4
Exterior Walls, cont.
Section 705 Fire Resistive Construction Fire Walls Fire Wall A fire-resistance rated wall having protected openings, which restricts the spread of fire and extends, continuously from the foundation to or through the roof, with sufficient structural stability under fire conditions to allow collapse of construction on either side without collapse of the wall. - structural stability Fire wall must stand if adjacent wall collapse - requires fire walls to be constructed of non-combustible materials except in Type V construction. Ratings for fire walls - based on the occupancies, for most a 3-hour wall is required. Table 705.4 allows 2-hours in type II and V for certain occupancies Where different occupancies are separated by a fire wall the more restrictive applies Review table 705.4 Horizontal Continuity 705.5 specifies that fire walls are to be continuous horizontally from exterior wall to exterior wall and extend 18 beyond the exterior surface of the exterior walls. Some exceptions Vertical Continuity 705.6 requires that the fire walls be continuous vertically from the building foundation to a point at least 30 above adjacent roofs.
Fire Resistive Construction Fire Walls
Fire Resistive Construction Fire Barriers Section 706 Fire Barrier A fire-resistance-rated vertical or horizontal assembly of materials designed to restrict the spread of fire in which openings are protected. fire barriers are similar to fire walls but with simpler criteria. They are used to separate vertical exit enclosures from other egress components, to separate different occupancies, or to divide a single occupancy into different fire areas. Required fire-resistance ratings for fire barriers are determined by their use. Ratings for barriers used in egress protection are rated per the applicable sections in Chapter 10 Egress Fire barriers are to be continuous between floor levels and extend to abutting adjacent interior or exterior walls. Prevent both smoke and fire, some penetrations are allowed but must be protected. Top of the floor assembly to the underside of the deck above. Continuous through concealed spaces. Supporting floor should have the same fire-resistance rating as the barrier
Section 707 Fire Resistive Construction Shafts Shaft An enclosed space extending through one or more stories of a building, connecting vertical openings in successive floors, or floors and roof. Shaft enclosures differ from fire barriers in that they typically enclose shafts extending through several floors. Shafts are often constructed of the same materials as barriers but the required ratings for shafts and vertical exit enclosures are usually determined by the number of floors that they connect. Per 707.2 all shafts need to be protected. 2- hours required if extending for 4 floors or more 1- hour if less than 4 floors (shaft ratings should be equal to those of the required floor assembly but not more than 2- hours) exceptions 707.2 read carefully 1. openings in residential units extending less than 4 stories need not be enclosed. 2. escalators or stairs not used as egress components (if sprinklered ) do not need protection 3. pipe, vent or conduit penetrations protected at the floor and ceiling according to section 711.4 need not be protected. 4. ducts protected per 711.4 do not need to be protected 5. atriums in offices and malls do not need specific shaft protection but a whole lot of other stuff 6. Chimneys do not need to be in a shaft but concealed spaces must be fire blocked 7. openings less than 2-stories that are not part of egress do not need to be protected 8. ramps in parking garages can be open 9. openings connecting mezzanines with space below do not need protection 10. expansion joints at floors and walls do not need to be enclosed but must be protected per 712 as for similar penetrations.
Fire Resistive Construction Shafts Section 707 Shafts can not have multiple purposes you can not use a vertical exit enclosure as your duct run Where ducts enter or exit a shaft a fire damper is required so when there is a fire the damper closes to keep the integrity of the shaft rating. Laundry and waste shafts must be separated from the rest of the building by 1-hour rated access rooms at each floor level they usually dump into a room in the basement these rooms require sprinklers. Elevator shafts 707.14 elevator shafts shall be constructed as other shafts adds the concept of lobbies to the mix. A rated lobby is required when an elevator opens onto an exit access corridor exceptions to lobby requirements 1. when building lobby levels are sprinklered in office the entry lobby can be open 2. with a fully sprinklered building less than 4 stories above the lowest level of firedepartment access lobbies may be eliminated
Section 708 Fire Resistive Construction Fire Partitions Fire Partition A vertical assembly of materials designated to restrict the spread of fire in which openings are protected Fire partitions are the next level of fire-resistive wall construction below fire walls and barriers. They typically have 1-hour fire-resistance ratings and are primarily used per section 310.3 for separations between dwelling units and guest rooms; per section 402.7.2 for separation of tenants in a covered mall and per section 1004.3.2 for exit corridors. Fire partitions have the same requirements for penetrations, openings and ductwork Fire partitions are to extend to the structure above and below with the following exceptions 1. When the floor is 1-hour rated the partition need not extend into the crawl space below. 2. When the room side fire rated membrane of a corridor extends to a fire-resistive floor or ceiling above, the corridor ceiling may be protected. 3. When the walls and ceiling form a tunnel the fir-rating need not extend above the top of the ceiling assembly. 4. In a covered mall building, partitions do not need to go to the structure between tenant spaces 5. In Group R-2, the fire partion does not need to continue up into attic space
Section 709 Fire Resistive Construction Smoke Barriers Smoke barrier A continuous membrane, either vertical or horizontal, such as a wall, floor, or ceiling assembly, that is designed and constructed to resist the movement of smoke. Section 709 treats smoke barriers as fire barriers, but with emphasis on restricting the migration of smoke. Smoke barriers are required to have a 1-hour rating with 20 minute opening protection. smoke barriers need to be continuous through concealed spaces unless they abut assemblies that will resist the passage of smoke, such as walls meeting fire-rated ceiling assemblies.
Section 710 Fire Resistive Construction Smoke Partitions Smoke partitions are not required to be rated unless they are required in a rated assembly. Continuity is required from floor to underside of deck above Openings Doors and windows should be self-closing and resist the spread of smoke from once space to another louvered doors are not allowed Joints and penetrations shall be sealed to eliminate the passage of smoke Smoke dampers are required for ductwork
Fire Resistive Construction Horizontal Assemblies Section 711 Horizontal assemblies are floor and ceiling/roof assemblies that require a fire-resistance rating. Their required fire resistance rating is determined by their use. The rating is primarily determined by the fire resistance rating based on type of construction as dictated in Table 601. When separating occupancies or dividing a single occupancy into fire areas, the fire resistance rating of the horizontal assembly must be examined against the requirements of Table 302.3.3 Horizontal assemblies have the same continuity requirements as for vertical assemblies. Penetrations, joints and ducts are to be protected as for vertical assemblies - 710.3.2 allows in 1-hour rated horizontal assemblies with crawl space or attic to be removed - Unprotected skylights are allowed in a roof as long as they meet the requirements of the adjacent structure in 704.10 - Any structural members or walls supporting a horizontal assembly must have at least the same fire-resistance rating.
Fire Resistive Construction Penetrations and joint Systems Section 712 This section requires that penetrations be protected to maintain the fire-resistive integrity of the assembly being penetrated. The governing criteria for protection are that they prevent the passage of flame and hot gases into or through an assembly. Two types of penetrations 1. thru penetration passes completely through the entire assembly 2. membrane penetration only passes thru a portion of the assembly. Sleeves securely fastened to the assembly Any space between the sleeve and the penetrating item or the sleeve and the assembly must be protected by an approved fire-stop material concrete grout can be used around concrete wall penetrations Electrical outlets on either side of a rated assembly shall be staggered not less than 24, or not less than the depth of the wall cavity that is filled with cellulose loose fill or mineral fiber insulation or solid blocking. protection of penetrations in horizontal assemblies is more restrictive than vertical assemblies because heat and smoke tend to rise. Higher rated stop system is required recessed lights can not reduce the ratings of ceilings special rated fixtures
Section 712-713 Fire Resistive Construction Penetrations and joint Systems Fire-resistant joint systems This section requires expansion, seismic movement and construction control joints to be treated in a similar manner to a penetration. The goal is that joints do not compromise the fire-resistive capabilities f the horizontal or vertical assemblies where they occur. Joints in fire-rated assemblies are to be fire tested to match the assembly rating. Joints are tested before and after movement to verify that they meet the requirements either way. joints at the intersection of floor assemblies and at exterior curtain walls are included in this section. Installed to prevent the spread of flame and hot gases
Fire Resistive Construction Structural members Section 715 Structural members and assemblies shall comply with the required fire-resistance rating per Table 601 and 602 supporting structural elements can not be less than the members they are supporting Columns, Girders, Beams if supporting multiple floors /roof than entire element needs to be protected individually protected on all sides. protection needs to be continuous if only supporting one story then can be encased or protected by a membrane, such as a ceiling or floor can not embed anything into the required protection layer no wires, conduits, etc. Exterior Load bearing walls reminder to review both tables 601 and 602 most restrictive is the one to follow
Fire Resistive Construction Opening Protectives Section 715 The requirements of this section for opening in a fire-resistive construction allow for the opening protectives to have different ratings than those for the wall. Tables 715.3 and 715.4 lists the requirements Opening protective are typically tested components glazed window systems or fire doors Fire doors are required to be self closing and latched (meaning when they are closed they can not be pushed open by fire drafts). Doors should be closed under most circumstances, can be on magnetic hold opens that release to close when an alarm is activated. Glazing in protected openings is limited by the code based on tested performance and the area of glazed openings. Wire glass can be installed with required thickness. High performance glazing can also be used much more expensive See Table 715.4.3
Fire Resistive Construction Opening Protectives
Structural Fire rating - diagram
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