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S&B Commercial Buildings Q&A - This is on a separate page because of the length of the answer Back to Commercial Buildings Q&A Main PageComm 61.03(6) and (7) Where an addition is proposed for a building that was constructed in compliance with the Commercial Building Code in effect prior to July 1, 2002, to what extent must the addition and the remainder of the building be evaluated for compliance with the current Commercial Building Code - Comm 61 to 65? (May 12, 2003) Answer: The Addition. Under Comm 61.03(6), the addition must comply with all of the requirements in Comm 61 to 65 that are applicable to it. However, the evaluation does not necessarily stop at this point, because additions to buildings may have significant impacts on or use various elements of the remainder of the building, such as fire-protection components, structural members, paths of egress travel, or plumbing fixtures. The Remainder of the Building. To evaluate the remainder of the building, keep in mind that under Comm 61.03(1), the construction criteria in Comm 61 to 65 do not apply retroactively - except where specifically stated in the rule - to any portions of the building which (A) existed prior to the July 1, 2002, effective date of Comm 61 to 65 and (B) are not being altered or modified. That retroactivity occurs very infrequently, and generally results from a specific, statutory requirement. Also keep in mind that the maintenance requirements in Comm 61.03(12) do not permit an addition or alteration for an existing building to result in the existing construction conflicting with any requirements of the Commercial Building Code which applied either when the building was built or when any subsequent additions, alterations, or remodeling occurred. If alteration or modification of any existing construction is needed in order to avoid that conflict, that alteration or modification is required by Comm 61.03(7) to comply with the associated construction criteria in Comm 61 to 65. As an exception, however, the stand-alone elements of Comm 61 to 65 that are less restrictive than preceding requirements can be applied to the existing construction, without a variance to Comm 61.03(12). These stand-alone elements include exit distance; exit width; nonenclosed stairways; noncascading of exit width, downward in stairways; and exhaust rates for certain occupancies, such as repair garages. The evaluation of the remainder of the building must also include consideration of elements therein that the addition will directly rely upon, through Comm 61.03(6), to achieve compliance with Comm 61 to 65. The Combination of the Addition and the Remainder of the Building. For both the addition and the remainder of the building, classification of the uses and occupancies is to be based on today's Comm 61 to 65. The classification of the type of construction likewise is to be based on today's Comm 61 to 65, for both the addition and the remainder of the building. For the remainder of the building, this classification usually will consist of selecting the IBC class of construction that most closely matches the individual characteristics of the existing construction, and generally will not include requiring modifications which are solely intended to make the existing construction more closely match that IBC class. When evaluating whether the requirements for the addition and the remainder of the building will be met, keep in mind the various design alternatives that are available in Comm 61 to 65, such as options for nonseparated or separated uses, potential use of either existing "building division" firewalls under IBC Section 705 or existing fire barriers under 302.3.3, and benefits which are given for providing automatic fire sprinkler protection. Note that in a mixed-use, nonseparated building, the nonseparated uses generally are treated as occupying a single fire area, so the fire-protection requirements and height limits for whichever use is the most hazardous will usually apply throughout that entire fire area. And, where an increase in floor area or building height results in exceeding a fire-sprinkler threshold in IBC Chapter 5 or 9, sprinklers will be needed either (1) throughout the building, or (2) in the fire area that contains the new floor area, if the building has been subdivided with one or more fire barriers into multiple fire areas. Also keep in mind the degree of hazard that will be posed in the addition, in combination with any hazards associated with other uses in the building or fire area. Note that inclusion of any "hazardous materials" - as they are defined and addressed in IBC Sections 307, 414, and 415 - is regulated significantly more under the current code than under previous codes, as is shown by the corresponding fire-sprinkler requirements in IBC Chapter 4. Examples. The following examples illustrate how to apply the fundamental concepts described above. In considering these examples, be aware that generally they each address a single topic, such as structural evaluation or exiting, and none of them should be interpreted as implying that other applicable requirements for other topics, such as for building height or plumbing fixtures, can be disregarded. Example 1 - An imposed, nonuniform structural load. A lateral addition is proposed for a building that was constructed in compliance with a version of the Commercial Building Code which preceded chapters Comm 61 to 65. The addition will be taller than the existing building. (No alteration of the existing construction is planned, and the existing construction will not provide structural support for the addition.) Any nonuniform load that will then occur on the existing, lower roof because of the addition's higher roof, such as from accumulation of drifting snow, must be analyzed for compliance with the code sections which were applicable at the time of construction of the lower roof, such as Ind 53.001(2)(k) and (3) in 1959, which included the following criteria: "The . . . live load requirements shall be considered only as a minimum. In every case where the loading is greater than this minimum, the design of the building or structure, or part thereof, shall be for the actual load and loading conditions." For this analysis, application of the criteria currently in chapters Comm 61 to 65 is recommended - but is not required, such as where an alternate recognized engineering method is used. If compliance with those previous code standards will occur, no alteration of the lower roof is required, regardless of whether Comm 61 to 65 now has more restrictive snow-load requirements. However, if compliance with those previous code standards will not occur, alteration of the lower roof is required. That alteration (such as a new beam and any support for it) must comply with all of the applicable criteria in Comm 61 to 65, including snow-load requirements and materials-of-construction requirements. Example 2a - Imposed live and dead loads. A lean-to addition is proposed for a building that was constructed in compliance with Comm 50 to 64, as they existed immediately prior to July 1, 2002. The existing building has a simple, two-sided gable roof, and the lean-to will be partially supported by one of the existing sidewalls. Analysis of any wind-driven snow from the lean-to side of the building onto the opposite side of the building is not required (and no corresponding alteration of that downwind side is required), because the structural criteria in Comm 53 did not require that analysis. In this circumstance, the lean-to addition will not place the existing, opposite side of the building in violation of a previous code standard. However, an analysis is required for the existing sidewall that will partially support the lean-to. First, Comm 53 is used to determine the loading from the existing construction onto the sidewall, and Comm 61 to 65 is used to determine the loading from the proposed lean-to onto the sidewall. If the combination of these two loads will not be supported by the sidewall in compliance with Comm 61 to 65, alteration of the sidewall is required. That alteration must comply with all of the applicable criteria in Comm 61 to 65, including use of Comm 61 to 65 to then determine the loading onto the sidewall from the existing construction. For example, this determination will include analysis of the wind-driven snow from the opposite side of the building onto the existing roof on the lean-to side of the building. (This determination is not required to include analysis of whether the tributary area of the existing roof complies with the Comm 61 to 65 snow-load requirements, because no alterations are either planned or required in that area. And, in some cases, use of Comm 61 to 65 to determine the loading onto the sidewall from the existing construction may show that no alteration is needed for the sidewall.) Example 2b - Imposed live and dead loads, under older codes. The same addition is proposed as in Example 2a, except the existing building was constructed in 1979 under the earlier, general structural standards cited in Example 1, rather than the more specific Comm 53 requirements cited in Example 2a. Consequently, analysis of any wind-driven snow from the lean-to side of the building onto the opposite side of the building is required, along with analyzing the wind-driven effects from the opposite direction, and alterations corresponding to that analysis may be required. As in Examples 1 and 2a, any such alterations must comply with all of the applicable criteria in Comm 61 to 65. Example 3 - Imposed egress loads. An addition is proposed for a building that was constructed in compliance with Comm 50 to 64 and 69, as they existed immediately prior to July 1, 2002. An occupancy in the addition will be served by an existing path of egress travel through the remainder of the building. The features of that path of travel which are occupancy-sensitive under the current code must be evaluated to see if they comply with today's Comm 61 to 65. These features include the width and length of the path, the door-opening directions, and panic hardware on doors. If this compliance will not occur, alterations must then be made to achieve it. As an exception, however, any fire-resistive ratings of enclosures along the path, that are occupancy-sensitive, can be left in compliance with the code in effect at the time of construction of the enclosure, rather than changed to comply with the current construction requirements. Any features of the existing path that are independent of the size of the occupant load and the type of occupancy - such as emergency lighting, minimum headroom heights, windowless floor levels, use of open stairways, egress through storage areas, and stair rise and run - can continue to be used and can be left in compliance with the code in effect at the time of their construction, rather than changed to comply with the current rules. Example 4a - Open spaces for unlimited-area buildings. A lateral, factory addition with unrated exterior walls is proposed along one side of a one-story, fully sprinklered, unlimited-area factory building that was constructed in compliance with Comm 50 to 64, as they existed immediately prior to July 1, 2002. The existing building sides that are not being expanded are adjoined by public ways or open spaces which are more than 30 but less than 60 feet in width, and which provide all of the street access required under Comm 54. To accommodate desired expansion of the factory's production lines into the factory addition, the owner wants to avoid putting a firewall or having any other separation between the existing building and the addition. The building addition must comply with all of the applicable requirements in Comm 61 to 65. For example, to retain the unlimited-area designation and avoid providing a firewall between the existing building and the addition, IBC 507.2 requires that a 60-foot-wide public way or open space adjoin and extend completely along the exterior walls of the addition. However, Comm 61 to 65 does not apply retroactively to the rest of the building exterior (because no alterations are planned there), so the public ways or open spaces along that part of the exterior are not required to increase to 60 feet in width, provided they are kept in compliance with the Comm 54 requirements which they were constructed under. Example 4b - Displaced open space. The same circumstances apply as in Example 4a, except the addition will displace part of the street access that had been required under Comm 50 to 64 for the preceding construction. That Comm 50 to 64 access must be reestablished elsewhere for the existing building, unless the 60-foot-wide public way or open space is provided around the entire perimeter of the combined building area. (May 7, 2003) The Department of Commerce Safety and Buildings Division is an equal opportunity service provider and employer. If you need assistance to access services or need material in an alternate format, please contact us, 608-266-3151, TTY 608-264-8777, or ttaylor@commerce.state.wi.us Links -- County Web sites || City/Town/Village Web sites || State Portal || Licensing and Permitting || Build Your Business Email this page's manager, Todd Taylor, ttaylor@commerce.state.wi.us or 608-267-3606 The Department of Commerce Safety and Buildings Division is an equal opportunity service provider and employer. If you need assistance to access services or need material in an alternate format, please contact us, 608-266-3151, TTY 608-264-8777, or ttaylor@commerce.state.wi.us |
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