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24D-174 2015irc_garage separationBUILDING PLANNING 2015 INTERNATIONAL RESIDENTIAL CODE® COMMENTARY 3-55 R302.5.2 Duct penetration. Ducts in the garage and ductspenetrating the walls or ceilings separating the dwelling fromthe garage shall be constructed of a minimum No. 26 gage(0.48 mm) sheet steel or other approved material and shallnot have openings into the garage. ❖Ducts are permitted to penetrate the required separa- tion (see Section R302.6) between the garage and dwelling unit when the ducts within the garage and the portion of the duct penetrating the wall are of No. 26 gage (0.48 mm) sheet steel or other materials accept-able to the building official. Steel ducts are required to help prevent the passage of an undetected fire withinthe garage to the dwelling unit (see Commentary Fig- ure R302.5.2). The opening limitation in the garage is to limit the path for smoke to enter the dwelling unit. R302.5.3 Other penetrations. Penetrations through the sepa-ration required in Section R302.6 shall be protected asrequired by Section R302.11, Item 4. ❖This section addresses the annular space that results from a penetration of the common wall by pipes, con- duits or ductwork. It is important that the building offi- cial verify that these spaces are properly filled and do not compromise the protection offered by the common wall between the residence and garage against the free passage of smoke, fire, noxious gases and odors. R302.6 Dwelling-garage fire separation. The garage shall beseparated as required by Table R302.6. Openings in garagewalls shall comply with Section R302.5. Attachment of gyp-sum board shall comply with Table R702.3.5. The wall sepa-ration provisions of Table R302.6 shall not apply to garagewalls that are perpendicular to the adjacent dwelling unit wall. ❖Numerous potential hazards exist within garages because occupants of dwelling units tend to store a variety of hazardous materials there. Along with this and the potential for CO build-up within the garage, the code requires that the garage be separated from the dwelling unit and attic as indicated in Table R302.6. Garage walls and ceilings that do not form a separationfrom the dwelling unit are not required to be rated unless they are an extension of a rated assembly. TABLE R302.6. See page 3-57. ❖This table specifies when and how the garage must beseparated from the dwelling unit and any attic space. Walls between the residence and the attached garage, or ceilings between the garage and an attic space, must have at least 1/2-inch (12.7 mm) gypsum board on thegarage side. If a habitable room is above the garage, the ceiling must be at least 5/8-inch (15.9 mm) Type X gyp-sum board on the garage side. Additionally, the exterior walls of the garage are required to have 1/2-inch (12.7 mm) gypsum board on the interior face where they sup- port floors separating all or part of a dwelling unit above the garage. Detached garages located less than 3 feet (305 mm) from an adjacent dwelling unit must be protected with at least 1/2-inch (12.7 mm) gypsum board applied to the interior side of the garage. The close proximity to adja- cent dwellings requires the additional protection. This 1/2-inch (12.7 mm) gypsum board is required even when the exterior walls are exempted by Section R302.1. The term “or equivalent” under each option allows for alternative means consistent with Section R104.11. There are two primary reasons for the enhanced fire endurance of a garage ceiling located beneath a hab- itable room. First, a fire occurring in a garage may well go undetected for an extended period prior to activa- tion of a detector or other visual alerting. Second, the inherent fire load and hazardous household activities associated with a garage neces- sitate this additional level of protection if fire suppres- sion forces are to have a reasonable opportunity to contain a garage fire to the area of origin. Figure R302.4.2(2) EXCEPTION TO ANNULAR SPACE PROTECTION Copyright © 2015 ICC. ALL RIGHTS RESERVED. Accessed by Louis Hasbrouck on Apr 2, 2018 10:20:26 AM pursuant to License Agreement with ICC. No further reproduction or distribution authorized. ANY UNAUTHORIZED REPRODUCTION OR DISTRIBUTION IS A VIOLATION OF THE FEDERAL COPYRIGHT ACT AND THE LICENSEAGREEMENT, AND SUBJECT TO CIVIL AND CRIMINAL PENALTIES THEREUNDER. BUILDING PLANNING 3-56 2015 INTERNATIONAL RESIDENTIAL CODE® COMMENTARY The single layer of 5/8-inch (15.9 mm) Type X gyp- sum board at the garage ceiling increases the fire endurance of the assembly considerably, from 15 minutes for a 1/2-inch (12.7 mm) layer, to at least 40 minutes, or a 167-percent increase in endurance. When added to the rating for floor joists and certain subflooring combinations, the final endurance is close to 1 hour. Commentary Figure R302.6 shows two locations of gypsum wallboard; each achieves the protection required by the code. R302.7 Under-stair protection. Enclosed accessible spaceunder stairs shall have walls, under-stair surface and any sof- fits protected on the enclosed side with 1/2-inch (12.7 mm)gypsum board. ❖Often times the space under a stairway is used for stor- age because this space is often of little use for other purposes. The code permits the use of an open space beneath a stair without the need for any additional pro- tection. Additionally, if the space is walled off and there is no access to the area, the code is also not con- cerned. If, however, the area beneath the stairway is enclosed and any type of access is provided into the space, the walls, soffits and ceilings of the enclosed space must be protected on the enclosed side with at least 1/2-inch (12.7 mm) gypsum board. For SI: 1 inch = 25.4 mm. Figure R302.5.2 GARAGE/DWELLING SEPARATION Copyright © 2015 ICC. ALL RIGHTS RESERVED. Accessed by Louis Hasbrouck on Apr 2, 2018 10:20:26 AM pursuant to License Agreement with ICC. No further reproduction or distribution authorized. ANY UNAUTHORIZED REPRODUCTION OR DISTRIBUTION IS A VIOLATION OF THE FEDERAL COPYRIGHT ACT AND THE LICENSEAGREEMENT, AND SUBJECT TO CIVIL AND CRIMINAL PENALTIES THEREUNDER. BUILDING PLANNING 2015 INTERNATIONAL RESIDENTIAL CODE® COMMENTARY 3-57 R302.8 Foam plastics. For requirements for foam plastics,see Section R316. ❖This section provides a cross reference to the foam plastic fire-resistant requirements for when this prod- uct is used within a home. Foam plastics are most commonly used in applications where their thermal qualities can be a cost savings for the home owner over time. R302.9 Flame spread index and smoke-developed indexfor wall and ceiling finishes. Flame spread and smoke devel-oped indexes for wall and ceiling finishes shall be in accor-dance with Sections R302.9.1 through R302.9.4. ❖Wall and ceiling finishes have requirements for flame spread and smoke-developed indexes, and testing, which are addressed in the following subsections. TABLE R302.6DWELLING-GARAGE SEPARATION For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm. SEPARATION MATERIAL From the residence and attics Not less than 1/2-inch gypsum board or equivalent applied to the garage side From habitable rooms above the garage Not less than 5/8-inch Type X gypsum board or equivalent Structure(s) supporting floor/ceiling assemblies used for separation required by this section Not less than 1/2-inch gypsum board or equivalent Garages located less than 3 feet from a dwelling unit on the same lot Not less than 1/2-inch gypsum board or equivalent applied to the inte-rior side of exterior walls that are within this area For SI: 1 inch = 25.4 mm. Figure R302.6 SEPARATION BETWEEN ATTACHED GARAGES AND DWELLING UNITS Copyright © 2015 ICC. ALL RIGHTS RESERVED. Accessed by Louis Hasbrouck on Apr 2, 2018 10:20:26 AM pursuant to License Agreement with ICC. No further reproduction or distribution authorized. ANY UNAUTHORIZED REPRODUCTION OR DISTRIBUTION IS A VIOLATION OF THE FEDERAL COPYRIGHT ACT AND THE LICENSEAGREEMENT, AND SUBJECT TO CIVIL AND CRIMINAL PENALTIES THEREUNDER.