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32C-212 2015irc_2 family separationBUILDING PLANNING 3-50 2015 INTERNATIONAL RESIDENTIAL CODE® COMMENTARY R302.3 Two-family dwellings. Dwelling units in two-familydwellings shall be separated from each other by wall andfloor assemblies having not less than a 1-hour fire-resistancerating where tested in accordance with ASTM E119 or UL263. Fire-resistance-rated floor/ceiling and wall assembliesshall extend to and be tight against the exterior wall, and wallassemblies shall extend from the foundation to the undersideof the roof sheathing. Exceptions: 1. A fire-resistance rating of 1/2 hour shall be permitted inbuildings equipped throughout with an automaticsprinkler system installed in accordance with NFPA13. 2. Wall assemblies need not extend through attic spaceswhere the ceiling is protected by not less than 5/8-inch(15.9 mm) Type X gypsum board, an attic draft stopconstructed as specified in Section R302.12.1 is pro-vided above and along the wall assembly separatingthe dwellings and the structural framing supportingthe ceiling is protected by not less than 1/2-inch (12.7mm) gypsum board or equivalent. ❖Most of the nation’s fires occur in residential buildings, particularly one- and two-family dwellings. These fires account for more than 80 percent of all deaths from fire in residential uses (including hotels, apartments, dor- mitories, etc.) and about two-thirds of all fire fatalities in any type of building. One- and two-family dwellings also account for more than 80 percent of residential property losses and more than one-half of all property losses from fire. Despite this poor fire record, there iswidespread resistance to mandating much in the way of fire protection systems or methods because of oursociety’s belief that people’s homes are their castles. This viewpoint has limited the types of protection that are imposed on these private homes to the installation of smoke alarms and the more recent requirement of dwelling unit separation. Section R302.3 provides a separation for protection of the occupants of one dwell- ing unit in a two-family dwelling from the actions of their neighbor in the adjacent dwelling unit. To accomplish this protection, the code addresses separation between the units, structural support and any openings or penetrations of the separation. Depending on the layout of the various dwelling units, Section R302.3 requires that the walls and/or floor assemblies that divide one dwelling unit from the adjacent unit be at least 1-hour fire-resistance rated. See Commentary Figure R302.3 for examples of the separation. The separation rating is to be determined by either ASTM E119 or UL 263, which is the normal test used for determining fire resistance. Many tested assemblies are available for use in these locations. The provisions of the section also address the con- tinuity of the separation, so that one dwelling unit is completely divided from the other. The horizontal aspect of the separation, which requires that the assemblies extend to and be tight against the exterior wall, is not difficult to comply with. It is most likely thevertical aspect (continuing a wall assembly to the underside of the roof sheathing) that will require somedetailed planning, careful construction and careful inspection for the units to be separated. Exception 1 grants a reduction in the required sepa- ration for those cases in which the building is equipped with an automatic sprinkler system. In these cases, a rating of 1/2 hour is permitted versus a 1-hour fire-resis-tance rating. The sprinkler system must be “installed in accordance with NFPA 13,” and is to be installed “throughout” the building. The type of sprinkler system Figure R302.3 DWELLING UNIT SEPARATIONS IN TWO-FAMILY DWELLINGS 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 3-51 used must meet NFPA 13 and may not be installed to either NFPA 13D or 13R, even though those two stan- dards do address certain types of residential uses. The word “throughout” requires that the sprinkler system be installed in all portions of both dwelling units and any common spaces. The provisions of NFPA 13 that per- mit omitting sprinklers in certain areas, such as small concealed spaces, are applicable. Therefore, the pro- vision requires a complying sprinkler system “through- out” the building (that is, in all areas of the building that must be protected according to the standard), and it does not accept any partial system, such as one installed in only one dwelling unit or only in the base- ment level of both units. Exception 2 addresses separation in the area of the attic of two-family dwellings or duplexes. As long as an attic draft stop is present that meets the requirements in Section R302.12.1, the 1-hour fire separation is per- mitted to stop at a ceiling constructed of 5/8-inch (15.9 mm) Type X gypsum board. This may be beneficial as, in many cases, the type of truss or attic rafter and rafter tie/collar tie configuration will prohibit continuing con- struction of the 1-hour separation wall all the way up to the roof sheathing. R302.3.1 Supporting construction. Where floor assembliesare required to be fire-resistance rated by Section R302.3, thesupporting construction of such assemblies shall have anequal or greater fire-resistance rating. ❖This provision applies only to walls that support the fire-resistance-rated floor assemblies that form theseparation between dwelling units in a two-family dwelling where the dwelling units are stacked verti-cally. When either all or portions of a dwelling unit sep- aration are provided by a floor assembly, the code requires that the structural supports for the separation have a rating equal to or higher than the floor. This is conceptually similar to the garage separation of Sec- tion R302.6. Without the supporting construction being protected, a fire on the lower level could lead to an early failure of the dwelling unit separation (see Com- mentary Figure R302.3.1). R302.4 Dwelling unit rated penetrations. Penetrations ofwall or floor-ceiling assemblies required to be fire-resistancerated in accordance with Section R302.2 or R302.3 shall beprotected in accordance with this section. ❖This section addresses the specific requirements for maintaining the integrity of fire-resistance-rated assemblies at penetrations. If the penetration of a rated assembly is not properly constructed, the assem- bly itself is jeopardized and may not perform as intended. The provisions of this section apply to pene- trations of fire-resistance-rated walls and floor/ceiling assemblies that are a part of the dwelling unit separa- tion in either two-family dwellings or townhouses. Pen- etrations of the rated assemblies range from combustible pipe and tubing to noncombustible wiring with combustible covering to noncombustible items, such as pipe, tube, conduit and ductwork. Each type of penetration requires a specific method of protection, which is based on the type of fire-resis- tance-rated assembly penetrated and the size and type of the penetrating item. The first step in determin-ing the type of penetration protection required is to identify whether a wall or floor/ceiling assembly isbeing penetrated. The next step is to determine the type of penetrating item and whether it is a membrane or through penetration. Once these factors are known,then the applicable section must be applied and the applicable method of protection must be decided upon. R302.4.1 Through penetrations. Through penetrations offire-resistance-rated wall or floor assemblies shall complywith Section R302.4.1.1 or R302.4.1.2. Exception: Where the penetrating items are steel, ferrousor copper pipes, tubes or conduits, the annular space shallbe protected as follows: 1. In concrete or masonry wall or floor assemblies,concrete, grout or mortar shall be permitted whereinstalled to the full thickness of the wall or floorassembly or the thickness required to maintain thefire-resistance rating, provided that both of the fol-lowing are complied with: 1.1. The nominal diameter of the penetratingitem is not more than 6 inches (152 mm). 1.2. The area of the opening through the wall does not exceed 144 square inches (92 900 mm2). 2. The material used to fill the annular space shall pre-vent the passage of flame and hot gases sufficient toignite cotton waste where subjected to ASTM E119or UL 263 time temperature fire conditions under apositive pressure differential of not less than 0.01inch of water (3 Pa) at the location of the penetrationfor the time period equivalent to the fire-resistancerating of the construction penetrated. ❖This section contains the general requirements for through penetrations, which are penetrations that pass through an entire assembly. A through penetration is in contrast to a membrane penetration, which creates a penetration through only one side of an assembly. Figure R302.3.1 SUPPORT OF DWELLING UNIT 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 3-52 2015 INTERNATIONAL RESIDENTIAL CODE® COMMENTARY Membrane penetrations are addressed later in Section R302.4.2. See Commentary Figure R302.4.1 for an illustration of these two types of penetrations. Through penetrations must be protected to maintain the fire resistance of the penetrated assembly. The code states two methods, found in Sections R302.4.1.1 and R302.4.1.2, which can be used to assure the adequacy of the penetration protection. The difference between these two is the test methodology used, but they both provide essentially the same results. The commentary for those sections is addi- tional discussion of the differences. Based on the history of these provisions and on the wealth of fire test data that exists concerning items such as conduit, water piping and other similar pene- trations, the code provides two exceptions that permit protection by methods other than those generally required. The first permits the use of concrete, grout or mortar to protect certain penetrations of concrete and masonry wall or floor assemblies. The concrete, grout or mortar must be applied for the full thickness of the assembly unless evidence can be produced demon- strating that the required fire-resistance rating can be achieved with a lesser depth. Concrete, grout and mor- tar have traditionally been used as protection for the annular space in penetrations of concrete andmasonry assemblies. Experience has shown this form of protection to be viable. However, caution must beused any time something, such as a water pipe or con- duit, is placed in concrete or masonry. Sections P2603.3 and P2603.5 contain examples of protection of plumbing systems. Exception 2 addresses the space between the pen- etrating item and the original assembly construction. This gap is called the annular space, and this excep- tion provides a method to simply evaluate the perfor- mance of the material used to fill that space. It is often mistakenly believed that this exception permits a vari- ety of untested items, but as can be seen from the pro- vision itself, the materials need to meet a specific performance level. This exception requires that the ability of the material to prevent the passage of flame and hot gases sufficient to ignite cotton when sub- jected to the time-temperature criteria of the ASTM E119 test standard be prequalified. This requirement is similar to provisions found in both ASTM E119 and ASTM E814, the standards used to evaluate fire-resis- tant assemblies and penetration protection. Because it is very likely that the penetration in the actual fire will be exposed to a positive pressure, this section specifies that the test-fire exposure include a positive pressure of 0.01 inch (0.25 mm) of water column as a further means to verify the performance of this protection method. Thus the protection will not be blown out or moved from its place during a fire. R302.4.1.1 Fire-resistance-rated assembly. Penetrationsshall be installed as tested in the approved fire-resistance-rated assembly. ❖This section addresses situations in which the penetra- tion is tested as a part of the regular full-scale test for the wall or floor/ceiling assembly. The penetration and proposed type of protection are evaluated as a part of the regular ASTM E119 test, which evaluates the wall or floor/ceiling rating. This section and the option it pro- vides are not used frequently because of the cost of conducting such full-scale tests and the limitations placed on the application of the tested assembly. Because of these issues, penetrations are most often protected in accordance with one of the exceptions in Section R302.4.1 or the provisions of Section R302.4.1.2. R302.4.1.2 Penetration firestop system. Penetrations shallbe protected by an approved penetration firestop systeminstalled as tested in accordance with ASTM E814 or UL1479, with a positive pressure differential of not less than0.01 inch of water (3 Pa) and shall have an F rating of not lessthan the required fire-resistance rating of the wall or floor-ceiling assembly penetrated. ❖Through-penetration firestop systems consist of spe- cific materials or an assembly of materials that are designed to restrict the passage of fire and hot gases for a prescribed period of time through openings made in fire-resistance-rated assemblies. To determine the effectiveness of a through-penetration firestop system in restricting the passage of fire, and to determine that the penetration has not jeopardized the original fire- resistant assembly, firestop systems must be subjected to fire testing using the ASTM E814 or UL 1479 test standard. This is a small-scale test method developed specifically for the evaluation of a firestop system’s abil- ity to resist the passage of flame and hot gases, with- stand thermal stresses and restrict the transfer of heat through the penetrated assembly. There are hundreds if not thousands of tested through-penetration firestop systems available today. The actual type of system used will depend on the type and construction of the assembly being penetrated, the material makeup and size of the penetrating item, and the size of the annular Figure R302.4.1 TYPES OF PENETRATIONS 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 3-53 space that exists between the penetrating item and the assembly being penetrated. Because there are a multi- tude of products available, and there is no “one size fits all” system available, it is helpful if the methods of pro- tection are included on the construction documents as covered by Section R106.1.1. The actual rating of the through-penetration firestop system is generated from the results of the testing and is reported as an “F” (flame) rating and a “T” (tempera- ture) rating. The code requires only an F rating. The F rating indicates the period of time, in hours, that the through-penetration firestop system remained in place without allowing the passage of fire during the fire expo- sure test, or the passage of water during the hose stream portion of the test. The required F rating must be equal to the fire-resistance rating of the wall or floor/ceil- ing assembly that is being penetrated. This means either a 1- or 2-hour rating, depending on the dwelling unit separation. Two of the most common materials used in through- penetration firestop systems are intumescent and endothermic materials. Intumescent materials expand approximately 8 to 10 times their original volume when exposed to temperatures exceeding 250°F (121°C). The expansion of the material fills the voids or openings within the penetration to resist the passage of flame,while the outer layer of the expanded intumescent material forms an insulating charred layer that assists inlimiting the transfer of heat. The expansion properties of intumescent materials allow them to seal openings left by combustible penetrating items that burn away during a fire, but they do not retard heat as well as endothermic materials. Intumescent materials are typically used with combustible penetrating items or where a higher T rat- ing is not required. Endothermic materials provide protection through chemically bound water released in the form of steam when exposed to temperatures exceeding 600°F (316°C). This released water cools the penetration and retards heat transfer through the penetration. Endother- mic materials tend to be superior in heat-transfer resis- tance and have higher T ratings, but they do not expand to fill voids left by combustible penetrating items that burn away during a fire. Therefore, endothermic mate- rials are typically used with noncombustible penetrating items and where a higher T rating is required. R302.4.2 Membrane penetrations. Membrane penetrationsshall comply with Section R302.4.1. Where walls are requiredto have a fire-resistance rating, recessed fixtures shall beinstalled so that the required fire-resistance rating will not bereduced. Exceptions: 1. Membrane penetrations of not more than 2-hour fire-resistance-rated walls and partitions by steel electri-cal boxes that do not exceed 16 square inches (0.0103m2) in area provided that the aggregate area of theopenings through the membrane does not exceed 100square inches (0.0645 m2) in any 100 square feet(9.29 m2) of wall area. The annular space between the wall membrane and the box shall not exceed 1/8 inch(3.1 mm). Such boxes on opposite sides of the wallshall be separated by one of the following: 1.1. By a horizontal distance of not less than 24inches (610 mm) where the wall or partitionis constructed with individual noncommuni-cating stud cavities. 1.2. By a horizontal distance of not less than thedepth of the wall cavity where the wall cav-ity is filled with cellulose loose-fill, rock-wool or slag mineral wool insulation. 1.3. By solid fireblocking in accordance withSection R302.11. 1.4. By protecting both boxes with listed puttypads. 1.5. By other listed materials and methods. 2. Membrane penetrations by listed electrical boxes ofany materials provided that the boxes have beentested for use in fire-resistance-rated assemblies andare installed in accordance with the instructionsincluded in the listing. The annular space between thewall membrane and the box shall not exceed 1/8 inch(3.1 mm) unless listed otherwise. Such boxes onopposite sides of the wall shall be separated by one ofthe following: 2.1. By the horizontal distance specified in thelisting of the electrical boxes. 2.2. By solid fireblocking in accordance withSection R302.11. 2.3. By protecting both boxes with listed puttypads. 2.4. By other listed materials and methods. 3. The annular space created by the penetration of afire sprinkler provided that it is covered by a metalescutcheon plate. ❖This section deals with instances where only a single side of the fire-resistance-rated assembly is pene- trated. This would be the situation for items such as electrical outlet boxes or plumbing fixtures located on one side of the wall only. Commentary Figure R302.4.1 shows this type of penetration. For the most part, a membrane penetration is to be protected by one of the previously described methods established for through penetrations. However, there are some penetrations that are allowed without a specific firestopping material in the annular space around them. These are addressed by the exceptions. This section also deals with the installation of recessed luminaires in fire-resis- tance-rated assemblies and states that their installation may not reduce the assembly’s protection. Although these fixtures are common, they do represent a pene- tration of the assembly’s protection and must be installed so that the assembly is not compromised. Exception 1 allows penetrations of steel electrical outlet boxes under certain conditions. The criteria of this section limit the size of the box to 16 square inches 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 3-54 2015 INTERNATIONAL RESIDENTIAL CODE® COMMENTARY (0.0103 m2) or less in area and to an aggregate area not to exceed 100 square inches (64 500 mm2) in each 100 square foot (9.3 m2) area. Commentary Figure R302.4.2(1) shows some of the requirements of this section. The area limitations are consistent with the cri- teria from fire tests, which have shown that within these limitations, these penetrations will not adversely affect the fire-resistance rating of the assembly. However, the boxes are assumed to be installed as they were during the fire tests. In general, the test requirements match the limitations shown by the code regarding their size and the need to be offset. An additional requirement, one that does not appear in the code, regulates the size of the annular space created around the outlet boxes. Both the Underwriters Laboratory’s (UL) Fire-Resis- tance Directory and the Gypsum Association’s Fire- resistance Design Manual specify a maximum over-cut of 1/8 inch (3 mm) for the annular space around the out- let boxes. Additionally, Article 314 of the National Elec- trical Code (NEC) (also known as NFPA 70) includes the size limitation of the over-cut. Therefore, the excep- tion applies only when the boxes are installed as they were during the original fire tests, including the limited annular space. Because outlet boxes on both sides of a wall create penetrations of both layers of a wall assem- bly’s protection, the code provides five methods to address this problem. This gives code users several options and does not limit them to the usual 24-inch(610 mm) offset. Exception 2 permits using outlet boxes of nonmetallicmaterials if they have been specifically tested. Because many different types of nonmetallic boxes are available, it is important to determine that the boxes being used in the rated dwelling unit separation have been tested. Although the exception applies to nonmetallic electrical outlet boxes, the same concept would apply to steel boxes that exceed the sizes specified in Exception 1. Exception 3 provides an alternative to the annular space protection provisions for a fire sprinkler that pen- etrates a single membrane. This exception is available if the annular space around the sprinkler is completely covered by an escutcheon plate of noncombustible material. The nature of the hazard posed by single- membrane penetrations of the sprinkler is limited by the size of the opening, the potential number of openings present and the presence of a sprinkler system. The installation of a noncombustible escutcheon provides protection against the free passage of fire through the annular space and allows for the movement of the sprinkler piping without breaking during a seismic event [see Commentary Figure R302.4.2(2)]. R302.5 Dwelling-garage opening and penetration protec-tion. Openings and penetrations through the walls or ceilingsseparating the dwelling from the garage shall be in accor-dance with Sections R302.5.1 through R302.5.3. ❖Openings to sleeping rooms from garages are not allowed because a person might not wake up in time if there was a hazard from CO fumes or smoke from the garage. The three subsections address doors, ducts and pipes. For wall and ceiling separation require- ments, see Section R302.6 and Table R302.6. R302.5.1 Opening protection. Openings from a privategarage directly into a room used for sleeping purposes shall not be permitted. Other openings between the garage and res-idence shall be equipped with solid wood doors not less than13/8 inches (35 mm) in thickness, solid or honeycomb-coresteel doors not less than 13/8 inches (35 mm) thick, or 20-min-ute fire-rated doors, equipped with a self-closing device. ❖Openings from the garage are permitted only into rooms that are not used for sleeping. These openings must be protected by the installation of a door comply- ing with the provisions of this section. The most com-mon situation is the door between the garage and the inside of the home. Solid wood doors 13/8-inches (35mm) thick, solid or honeycomb steel doors and 20-min- ute fire-rated doors are required for use in the opening between the garage and dwelling unit. A self-closing device must be installed on these doors as a safeguard to limit free flow of carbon monoxide or other products of combustion into the living area. For SI: 1 inch = 25.4 mm, 1 square inch = 645 mm 2, 1 square foot = 0.0929 m2. Figure R302.4.2(1) MEMBRANE PENETRATION BY OUTLET BOX 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.