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HomeMy WebLinkAboutFire Separation RequirementsGarfteld County BUILDING DEPARTMENT 108 E¡ghth Street, Suite 4O7, Glenwood Spr¡ngs, CO 87607 Tel: (97o) 94U8272 POLICY DIRECTIVE & INFORMATION SHEET August2ol9 Fire Separatíon Requ Írements at Two-Family Dwellings - lncludíng ADUs Two-Fomily Dwellings - includÍng Secondøry or Accessory Dwelling Units (ADU) Iocoted within the søme structure øs ø primary dwellíng unit- invoke certa¡n Building Code provisions requirÍng proper detailíng ol construction ossemblies by the designer, øs well øs proper execution dt the iob site by the builder. Building Code requirements for "two-family dwellings" include fire-rated construction assemblies at walls, floors and/or roofs, as well as penetrations occurring in these fire-resistant building elements. Fire separation requirements of two family dwellings are desribed in detail in Sections R302.3-R302.4 of the 2015 lnternational Residential Code. For more detailed information, refer to the attached requirements as excerpted from l.R.C. Code & Commentary - Volume 1. Garfield County residentiol projects with two or more dwelling unìts in the same structure require o Colorado licensed Archítect. The Architect shall specifically address key fire resistance provisions of the Building Code (as referenced above), and the Architect must wet seal/stamp drawings submitted along with the building permit application. Drawings prepared by the Architect and submitted to the Building Department shall include: 1. For All Proiects - Clearly identify location and extent of all fire-rated assemblies between adjacent dwelling units - as shown on floor plans, building sections, details - and including the following requirements: a. Construction assemblies of both vertical and/or horizontal separations are required to meet a one-hour fire-resistance rating (*Note: Fire sprinklers reduce fire-rating to 30 minutes). b. Floor/ceiling and wall assemblies shall extend to and be tight against exterior walls. Wall assemblies shall extend from foundation up to underside of roof sheathing. c. Where floor assemblies are required to be fire-resistance rated, supporting construction (walls, beams, posts) shall have an equal or greater fire-resistance rating. d. Penetrations (including electrical, recessed lights & mechanical ductwork) located within fire-rated assemblies shall comply with specific requirements. 2. For New Construction Proiects - Show detailed drawings or otherwise describe wall, floor, ceiling, and roof fire-rated assemblies. Reference numbers of approved construct¡on assemblies from nationally recognized agencies (for example, Underwriters' Laboratories, U.S. Gypsum Association, etc.) may be submitted, but descriptive specifications and/or illustrations must also be included. 3. For Retrof¡t/Remodel Pro¡ects - ln lieu of specific documentation for the original structure, the Building Department may accept installation of (2) layers of 5f 8" Type X drywall at one side of wall, floor/ceiling, or roof assemblies to provide the required one-hour fire rating between adjacent dwelling units. The Architect may otherwise provide alternative fire resistance rating for assembly components as per chapter 7 of the 2015 l.B.c. Attachments: . 'Two-Famity Dwettings - Fire Separotion Requirements" os excerpted from 2015 l.R.C. Code/Commentory Two-Family Dwellings: Fire Separation Requirements R.302"2.4 Structural independence. Each individtal town- /¿¿,¿rse shall be stluctulally independenl". Exceptionsr 1. Foundations supporting exterior yvalls or comlllon walls. 2. Structural roof and wall sheathing from each unit fasteneci to the common wall framing. 3. Nonstnrctural wall and roof coverings. 4. Flashing at termination of roof covering over com- mon wall. 5. Toyvnhouses separated by a common wall as pro- victed in Section R302.2,Item I or 2. "þ Each townhouse must be structurally independent and capable of being removed without affecting the adja- cent dwelling unit. This provision is applicable only to townhouses, not two-family dwellings. This indepen- dence is useful not only in the event of a fire in one unit, but also during any remodeling or alteration. The objective of this structural independence is that a com- plete burnout could occur on one side of the wall with- out causing the collapse of the adjacent townhouse, This condition occurs rarely. The provision also helps if there is ever a fire or other problem by creating a clear separation between the units. With separate owner- ship and each owner having a different insurance com- pany, the ability to gain access or get repairs made can be difficult and time consuming. By having clearly sep- arated units, it is much easier to determine who is responsible and to make any needed repairs. The code lists five exceptions that waive the struc- tural independence requirement. A quick review of the exceptions shows that they generally deal with items BUILDING PLAhINING that will not structurally affect townhouses should a problem develop in the adjacent dwelling unit. Excep- tion 1 is based on the norm within the industry for foun- dation construction. ln the code, Section R402 lists only wood and concrete within the foundation materi- als section, although Section R404 accepts masonry foundation walls. ln general, concrete and masonry are the most common types of foundations;wood foun- dations are viewed as unique. Given the performance of both masonry and concrete, and the fact that these foundation systems must sustain loads from both the structure and the adjacent soils, it is reasonable to assume that the foundation will not be the item that fails in most situations, Permitting a common founda- tion also helps solve other problems that would arise if the structural independence issue were taken as an absolute. An example where requiring separate foun- dations would probably create more problems or diffi- culty is in the dampproofing or waterproofing of below- grade foundation walls. lf a wood foundation is used between adjacent units, what is the level olfire protection that may be needed? Because concrete and masonry foundations are the norm, it would be easy to forget or overlook protecting the foundation when it is constructed of wood. ln these cases, it would seem appropriate to deal with the foun- dation as any other wall, and protect it on any exposed side. The levelof fire resistance should be equalto that of the wall or walls that the foundation supports. R302.3 't'wo-lhmily dwellings. Dwellíng units in two-family dwellings shall be separated from each other by wall and floor assemblies having not less than a l-hour fire-resistance rating wl'rer:e tcsted in accordauce with ASTM E1 19 ur UL 263. Firc-rcsistance-rated floor/ceiling and wall assemblies ROOF MORE. SLOPE THAN 2:THAN ROOF ROOF SLOPE OF 2:12 OR LESS 30 tN. MtN (ADJACENT ROOF NOT SHoWN FoR CLARITY) For Sl: 1 inch = 25.4 mm, 304.8 mm. Figure R302.2.3 PARPET REQUIREMENTS 2015 INTËRNATIONAL RESIDENTIAL CODEO COMMENTARY 3-47 shall extend to and be tight against the exterìor wall, andwall assemblies shall extcnd from the foundation ¡o the underside of the roof sheathing. Exceptions: BUILDING PLANNING 1. res occur particularly one- and two-familY dwellings. These fires account for more than B0 percent of all deaths from fire neighbor in the adjacent dwelling unit' To accomplish thiJ protection, the code addresses soparation between the units, structural support and any openings or penetrations of the seParation, Depending on the layout of the various. dwelling unlts, Sectlon R302.3 requires that the walls and/or floor assemblies that dívide one dwelling unit frorn the adjacent unit be at least 1-hour fire-resistancd rated' See Commentary Figure R302.3 for examples of the separalion. The separation rating is to be determined by'elther ASTM E119 or UL 263, which is tho normal test used for determining fire resistance. Many tested assemblies are available for use in these locations. The provisions of the sectlon also address the con- tinuity ôf the separation, so that one dwelllng unit ls comþletely divided from the other. The horizontal aspdct of the separation, which requires that the assemblies extend'to and be tight agaínst the exterior wall, is not difficult to comply with. lt is most likely the vertical aspect (continuing a wall assembly to the underside of tho roof sheathing) that will require some detailed planning, careful construction and careful inspection for the units to be separgted Exception 1 grants a reduction in the required sepa- ration fór thoselases in which the building is equipped with an automatic sprinkler system. ln these cases' â rating of 1/, hour is permitted vêrsus a 1-hour fire-resis- tance rattng. The sprlnkler sy$tem must be "installed ín accordance with NFPA 13," and is to be installed "throughouf'the building. The type of sprinkler system used ñust 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 sysiem be installed in all portions of both dwelling units and any + in residential uses (including hotels, and about two-thirds of apartments, dor- mitories, etc.) any type of building One- and two-familY also account for more than 80 percent of allfire fatalities in dwellings residential nrooertv losses and more than one'half of all property iosées irom fire. Despite this poor fire reôord, there is widespread resistance to mandating much in the way of fire protection systems or methods because of our society's belief thai people's homes are their castles' This viewpoint has límitéd the types of protection that are imposed on these private homes to the installation of smóke alarms and ihe more recent requirement of dwelling unit separation. Section R302.3 -provides a separaäon for pròtection of the occupants of one dwell- in j unit in a twó-family dwelling from the actions of their I,HR FLOOFÍCÊILING ASSEMBLY TO EXTEND TO ËrlÉRIOR WALL ISUPFORT PER SECTION RAO?.3,I ls REQUTRED) FI DWELLING UNIT SEPARA gurc R302.3 TIONS lN TWO-FAMILY DWELLINGS 2. Wall assemblieþ need not extend through øflic-spaces whcrc thc ccilirg ís protected by not leas than'/r-inch (15.9 mnÐ TYpe X Sypsum board, an ørtic draft stop constructed as specified in Section R302'12.1 is pro- yided above and along the wall assembly sepÂrating the r/u,elliq,r and the structutâl fiarning $upponing the ce,iliug i* p,ot""t"d by mrt lesn than r/r'inch (12'7 rnm) gypsum board or eqnivalent. ATTICATTIC DWELLING UNIT B DWELLING UNITA DWELLING UNIT B DWELLING UNITA DWELLING UNITA DWELLING UNIT B 3.48 201 5 INTERNATIONAL RESIDENTIAL CODEO GOMMENTAFY common spaces. The provisions of NFPA 13 that per- mit omrttlng sprinklêrs ln ceñaln areas, such as s¡tlall concealed spaceg, are applicable. Therefore, the pro- vlsion requires a complying sprinkler systom'Ïhrough' 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 ín 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 prasenl that megts the requirements in Sectlon R302.12.1,the 1-hourflre separation is per- mltted ts stop at a ceiling constructed of 5/s-inch {15.9 mm)Type X gypsum board. This may be beneficial as, in manycases, thetype of truss orattic rafterand rafter tie/collar tie configuration will prohibit continuing con- struction of the 1-hour separation wall allthe way up to the roof sheathing. R302.3.1 Supporting construction. W}¡ere floor assemblies are required to be fire-resistance rated by Section R302.3, the supporting construction of such assemblies shall have an equal or greater fire-resistance rating. ¡t This provision applios only to walls that support the fire-resistance-rated floor assemblies that form the separatlon between dwelling units in a two-family dwelling where the dwefling units are stacked vertl- cally. When either all or portions of a dwelling unit sep- aration are provided by a floor assembly, the code requiros that the structural supports for the separation have a rating equal to or higher than the floor, This is conceptually simílar to the garage separation of Sec- tion R302.6. Without the supporting constructign 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 ). DWELLING UNIT SEPARATION Figure R302.3.1 SUPPORT OF DWETLING UNIT SEPARATION R302.4 Drvelling unit rated peletrations, Penel¡arions ol' tvülì or fluur-cuílirrg asserubliuu requirctl to bu fìtp-rssistancc rnetl in accordanee rvith Scction Iì302,2 or R302.3 shall be protected in accordance with this section. $ l'his section addresses the specific requirements for Itnintaining the integrity of fire-resistance-rated EUILDINO PLANNING assemblies at penetrations. lf the penetration of a rutod assenrbly is trot pruperly uonstructed, tl¡c sssetrl- bly ltself is jeopardized and may not perform as intended. The provisions of this seclion apply to peno. trations of fire-resistance-rated walls and floor/ceiling assemblies that are a part of the dwelling unit separa- tion in either twô-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 requíres a specific method of protection, which ls based on the type of fire-resis- tance-rated assembly penetrated and the slze and type of lhe penetrating item. The first step in determin- ing the type of penetration protection required ls to identify whether a wall or floor/ceiling assembly is being 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 of fire-resistance-rated wall or floor assemblies shall comply with Section R302,4.L1 or R302.4.1.2. Exception: Where the penetrating items are steel, ferrous or copper pipes, tubes or conduits, the annular space shall be protected as follows: 1, In concrete or masoffy wall or floor assemblies, concrete, grout or mortar shall be permitted where installed to the full thickness of the wall or floor assembly or the thickness required to maintain the fire-reslstance rating, provided that both of the fol- lowing arê complied with: 1.1. The nominal diameter of the penetrating item 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 mmz). 2. The material used to fill the annula¡ space shall pre- vent the passage of flame and hot gases sufficient to ignite cotton waste wherç subjected to ASTM El19 or UL 263 timc temperature fire conditions under a positive pressure differential of not lcss than 0.01 inch of wáter (3 Pa) at the location of the penetratíon for the time period equivalent to the fire-resÍstancc rating of the construction penehated. * This section contains the general requirements for through penetrations, which are penetrations that pass through an entire assembly, A through penetration ís in contrast to a membrane penetratíon, which creates € penetration through only one síde of an assembly, Membrane penetrations are addressed lator in Section R302.4.2. See Commentary Figure R302.4.1 for an illustralíon of these two typos of penetrations. Through penetrations must be protected to maintain the fíre resistance of the penetrated assembly. The code states two methode, found in Sections R302.4.1.1 and R302.4.1.2, which can be used to t DWELLING UNIT B 2015 INTERNATIoNAL FEsIDENT|AL coDEo coMMENTARY 3-49 SUILDING PLANNING THROUGH PENETRATION sEc. R3024.1 sEc, Figure R302.4,1 TYPES Op penern¡TloNs tantassèmbl¡es ând psnetration proJection' Bgcause it il uerv ttf"tv that the irenetration in the actual I'ire will be "xpo,íeà icí á positive pressure,.this s€ct¡on speclfles Ûrå tne ts t-fiie exposuro ìncluda a positivê pressufe ãii,ôî ¡nCn P'as inm) or waler colu-mn.as â furthor meäne to verity the performance ol this. protootìon meihoO, Thus'tho proiaction will not be blown out or moved from its Place during a fire' R302.4,1.1 Flre-reslstnnce'rated assembly' Penetrations shall be installed as tested in the øpproved fire'resistance' rated asseurblY. $ This sectlon addresses situations in which the penetra- isn is têsted as q part of the regular full-scale test for iitã w"tt or noor/ce¡ilng assembly-. Tho ponotratlon and ðróooiào tvpe of proiãotion are-evaluated as a parl of [nãrouiaiÄsTM Er 19 test, which evaluates the wall or flooi/ceillng rating. This section and tho oplion it pro- vi¿"s áre noi usadfrequently because of thê cost of i*Orãi¡ng such full-sòale tests and the linritations 'oUcàO oñ tre application of the tested assembly' bÃ.aus" of these'ibsu6s, penêtrations are most often ãr"teðtø in accordance with sne of the exceptions in $"tiın R302.4.1 or the provisions of Section R902.4.1.2. R302.4,1,2 Penetration firestop sy$tem. Penetrations shall be prntecteil by an ¿Ipr¡t'overl penetration firestop system instalted as tesie<t ilr acc,r¡rdancè with ASTM E8l4 or UL i¿ZS, *itl, a positive pressure diff'erentiat of .not less than ô.0 f in"i, of wätcr (3 PÐ and shall have an F rating of not less rhan the required fire-resistance rating of the wall o¡ floor- ceiling assemblY Penetrated, tr Through-penetration firestop systems consist of spe- cific rñaÎårlals or an assembly of materials that are desigrred to restrict the pagsage of fire and.hot gases ior å"prescrl¡ed period cir timelhroug¡ openings made in niä-resistance'rated asssmblies. To dstsrmine the éffectiveneqs of a tlrrough-penetration líç9top,sysl9Íl in i"çtt¡"ting the passagã of fire,.and.to determine that tri" páneirãtion ñas nıt jeopardlzed the.original fíre- resiétant assembly, firestop systerns rnust be subjected tã iiie testing uslng the ÀsïM 8814 or UL 1479 test JtanoarO. Tdis is airnalþsoale test method developed iòãcif¡callv for the evaluation of a firestop system's abil- Ñ to resis:t the passage of flame and hot gases, wlth- "i"n¿ ttrermalsiresseı and restrict the transfer of heat if¡råugn the penetrated assembly. There are hundreds ¡f not-thousdnds of tesled through-penehation firestop sv.qlams available todav. The actual type of system uäã¿ *¡l depend on thé type ancl con'struction of the ärããrnniv oeing penetrateð, tne matorial makeup and ilzlot tne penıtiat¡ng ltem, and the slze of.the annular siãce ttrat'exiets betúeen the penetrating item and the elsemblv beinq penetrated' Bécause there are a multi- tu¿e ôt óio¿ucis'avallabls, and there ig no uone slze flts àti;sysiem available, it is helpful:if the methods of pro- tectidn are included on the construcllon documerits as covered bY Section R106.1.1'- The actúal rãtlng of thu through-ponetration firostop sysieinii g"neratãd trom the resufis of the lesting and 2OI 5 INTERNATIONAL RESIDENTIAL CODE6 COMMENTAHY assurethe adequaCy of the penetrallon proteclion' The ãner*nã" betwben inese two is the test methodology ö;d; ';"ì tnäv oottr provide essentiallv the samê r"*ufh. rn* cómmentàry for those seetions is addí- tional discussion of the dlfferences.--gãsed on the h¡story of theso provisions and on the weãifi-ðirne test daÍa that exists concerning items sucf, ãs condult, watet plplng and other simllar pene- iËii.;*, itre ãó.t'e provide's Ño e,xceRllons that permit öøiãdt¡äñ ¡y meinoOs other thaq those. generallv iáoulre¡. Thé first permits the use'of concrote, grout or ;ðrtä; It protàct iertain penelrations of concrête ând rã*ınrv wrll or floor ass-enrblies' The concrete' g,rgut ôi r*üår miisi'oe applied for the full thickness of the ãssémory unless ovidence can be produoed demon- ãirat¡,iıir'ut ihe required fire-resistance ratlng can be ããñiàväãwitn a lesderdepth. Concrete, groutand mor- taî f'ávã traaitionally been used âs protection. for the ;rnrd; ãpãð" in' penetrations of concrets and ."älä"* aisemblies"Experience has shown this form ;ööt"ä¡* tô 6e u¡aot¿. However, cautlon must be uråO any time something, such as awater pipe or con- ðui-t, Ë'ptãced in contrete or masonry Sections på6bs.g ãno paoog,s contain examples of protection of olumbinq svstoms.- Ë*"àot¡o-n á addresses the spâce betwoen the pen' etraiìnl¡tãt and the originãl ássembly construction' This gãp is called the annular space,.and this excep- tion Jtoi¡Oes a method to slmply evaluate the porfor- ;;;ã";iiñã material used to htitnat spaoe' lt is often ilìËtãr,"îlü oelievect that this êxception permits a vari- ätv àîuitísted iterns, but as can be sesn from the pro' iiJion-it*ãlr,-thã maìeriats need to meet a gpeqif¡c oãrriità'i"å level' This exception requires that the äoilifv ðitt" material to prevent thê passagê of flarne ;;d'ili fasos sufficieni to ignlte. cotton- when ¡gþ; Ë"i"ä to"tnu fime-temperatuie ctiteria of the ASTM Ëirs t"ãtàtãnouta oe prequalified, This requirement is ;"ril";i"-ilóuii¡ons fbunà ¡n both AsrM E11e and ÃêîM eer'¡, tl'e standards used to evaluate fire'resis- 3-50 is reported as an "F" (flame) rating and a "T" (tempera- lure) rating. The code requires only an F rating. The F ratlng indicatos the perlod of time, ln hours, that the through-penetration firestop system remained ln place without allowing the passage of ffre during the fire expo- sure test, or the passage of water during the hose stream portíon of thetest. The required F rating mustbs equal to the fire-resistance rating of the wall or floor/ceil- ing assembly that ls being penetratêd. Thls mesns either a 1- or 2-hour rating, depending on the dwelling unit seParation. Two of the most common materials used ln through- penelration flrestop systems are intumescent and endothermic materials. lntumescent materials expand approximately I to 10 times their original volume when exposed to temperatures exceeding 250'F (121'C). The expanslon of the materlalfllls the volds or openings within the penetration to resist the passage of flame, while the outer layer of the expanded intumescent materialforms an insulating chared layerthatassists in limiting 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 fíre, but they do not retard heat as well as endothermic materlals, lntumescent materials are typically used with combuslible penetrating items or whers 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 flll voids left by combustible penetrating items that burn away during a fire, Therefore, endothermic mate- rials are typically used with noncombuslible penetrating items and where a hígher T ratlng is required. R302.4,2 Membrane penetrations. Membrane penebations shall comply with Section R302.4.1 , Whcre walls are retluircd to have a fire-resistance rating, recc,ssod fixtures shirll be inslülled so that the rec¡uired fire-resistance rating will not be reduced, Exceptions: 1. Membrane penetrations of not more than 2-hour fire- resistançe-rated walls and partitions by steel electri- cal boxes that do ¡rot exceed 1 6 square inches (0.0103 m2¡ in area provided that the aggrðgate area of the openings through the membrane does not exceed 100 square iuches (0.0645 m2¡ in any 100 squrue feet (9 .29 m2) of wall a¡ea. The annular space betweer¡ the waII membrane and the box shall not exçccd l/u inch (3,1 mm). Such boxes on rrpposite sides ol'the wall shall be separated by trne of tlte fulluwing: 1.1. By n horizontal distnnce of not less tha¡24 inches (610 mm) where the wall or partition is co¡¡structed with individual noncommuni- cating stud cavitjes. BUILOING PLANNINO L.2. By a horizontal distance of not less than the depth of the wall cavity where the wall cav- ity is filled with cellulose loose-fiIl, rock- wool or slag mineral wool insulation. 1.3. tsy solid fireblocking in accordance with Spction R302.11. 1.4. By protecting both boxes with ,¡rt¿d putty pads. L.5. By other l¡',rferJ materials and methods. 2. Membrane penetrations by lßted electrical boxes of any materials provided that the boxes have been tcstcd fr:r use iu firs-¡osistaluc-lalud asuor¡ilrlics a¡rd are iustalled in accordance with the instructions included in the listing.The annulal space between the wall membrane and the box shall not exceed r/, inch (3.1 mm) unless /¡'sf¿d otherwise. Such boxes on opposite sides ofthe wall shall be separated by one of the following: 2.L. By the horizontal distance specified in the /rstlng of the electrical boxes. 2.2. By solid fireblocking in accordance with Section R302.11. 2.3. By protecting both boxes with /Ísrød putty pads, 2.4- By o|}ie¡ listedmaterials and methods. 3. The annular space created by the penebation of a fire sprinkler provided that it is covered by a metal escutcheon plate. S This section deals with instances whare only a single side of the fire-resÍstance-rated assenrbly is pene- trated. Thís would be the situatíon for items such as electrical outlet boxes or plumbing fixtures located on one side of thewallonly. Commentary Figure R302.41 shows this tyæ of penetratlon. For the most part, a membrane psnetration 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 materialin the annulâr space around them. These are addressed by the exceptions. This section also deals with the installation of recessed luminalres in flre-resis- tance-rated assemblies and states that their installation may not reduce the assembly's protêction. Although these fixtures âre cornmon, they do rêpr€sont a penê- tration of the assembly's pfotêction Bnd must be installed so that the assembly is not compromised. Exception '1 allows penetrations of etesl electrical outlet boxes under certain conditions. The criterla of thls section limit the size oJ the box to f 6 sguare lnches (0.01 03 m?) or loss in area and to an aggregate area not lo exceed 100 square inches (64 500 mm?) in each 100 qqqqro foot (0.t m?) area. Commcntary Figure R302.4.2(1) shows some of tho roquiroments of thls sgction. The area limitations are consistent with the cri- terla from fire tests, which have shown that wíthin these lirnilallons, these penetratlons wilf not advcrsely affect the fire-resistance ratlng of the assenrbly. However, the 2015 INTERNAT¡oNAL REstDENTtAL coDeo coMMENTAFy 3.51 boxes are assumed to bo instâlled as they were durlng tne Rre tests. ln general, the test requiremants match the limitations shówn by the code regardlng thelr size and the need to ba offiet. An additional rêquirement, one that does not appear in the code, regulates the size of the annular spacá created around the outlet boxes' goth thà Unden¡¡riters Laboratory's (UL) Fire-Rasís- tance Dlrectory and the Gypsum Association's Fle- ¡esisfance Deéign Manuat specifo a maxlmum.oler-cut of rL lnch (3 mm) br the annular space around the out- Ët o"oies. h¿¿tt¡ónallv, Article 314 of the Nationa/ E/ec- tricatCode (NEG) (aiso known as NFPA 70) includes the size limitàtlon-of tne over-cut. Thsrefors, the excsÞ- tion applies only when the boxes ars lnstalled as they wãr äürlng lhe original fire tests, including the limited ànnutàr spãce. Becãuse outtet boxes on both sldes of a wall creade penetrations of both layers-of a wall.assem- blv's proteótlon, the code provides flve methods to ãÚ¿r"iJir,¡" próblem' This'gives code users several ôóf¡onJaÀ¿ does not limit tñem to the usual 24-inch (610 mm) offset.' Exceoúon 2 permits using outlet boxes of nonmetallic materlais if thei have been specificallytested' Because many different types of nonmetallic boxes are available, it is important to determlne that the boxes belng used in the raied dwelling unit separation have been tested. Although the oxception applies to nonmetallicelectrical outþt 6oxes, the 'same concopt ulould apply to eteel boxes thal exceed the sizes specified in Exception 1' Exception 3 provides an alternalive to the annular space ¡irotection provisions for a f iro sprinklorthatpen- eirates a single membrans. This exception is avallable if the annulai space around the sprlnkler is completely covered by an escutcheon plate of noncombustible malarial. fhe naturs of the hazard posed by single- membrane penetratione of the sprlnkler ls llmìted by the size of the bpening, the potential number of openings present and ihe piósenie of a sprinkler system. The installation of a rioncombustible escutcheon provides protection against the free passågo of firo through the ännular spaie and allows for the movement of the sprinkler piping without breaking during a seismlc event ldee Commentary Figure R302'4.2(2)l' BUILOI¡¡G PLANNING CEILING MEMBRANC E8CUTOHEON PLAÍE PENDENT SPRINKLER Flgurt R302.4.2(2) EXCEPTION TO ANNULAR SPACE PROTECTION COMPLYING ELECTRICAL FIRE-RESISTANCE. RATED WALL MIN 24 lN, SEPARATION BOX SIZE: 5 16 SQ lN. WTH MÆ( OF l OO SQ IN, PER 1OO SQ FT OF WALL ,,rrrurr#8,ff8Jl?ËP5#8"'*''o' For Sl: 1 lnch = 26.4 mm, 1 square lnch = 645 mmz' 1 squaro foot = 0'0929 m¿' Flgure R302.¿l'2(l) I'EIJIBRANE PEÑETRATION BY OUTLET BOX 3'52 2015 INTERI.¡AIIONAL RESIDEINAL CODE. COÍIIMENTARV