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13120166 - AMMR , ;.i.1c 14l � Irvme,CA9261[�, . _� _ 714.369.1890 D E S I G N A N D A R C H I T E C T U R E 24 January 2017 � . . . . ... :, v�a'Li� i 1�� :<;...; �;::;!r�ir,� 7�r,�<^,trn�nt Albert Salvador � Building Official �- . . ;; ., ,. �;. : City of Cupertino, Building Division : i � 10300 Torre Avenue � Cupertino, CA, 95014 �_� ;; ,-;�. '. : �K t;;;!J� GOiv1�L'IA/�JCE Re: Roof Insulation at Main Street Cupertino Lofts, ��� ''" " ' '�j� ��" Permit# 13120166 Main Street Cupertino Loft Residences, Cupertino, CA Dear Albert, We have been working with South Bay Construction and Sand Hill Construction Management to explore an alternate to insulating the unvented flat roof/ceiling assembly on MSC Lofts. These efforts include approval to waive attic ventilation per CBC Section 1203 by way of"Alternate Materials & Methods/ Modification Form"dated 01/12/2017. Also,we have reviewed the project's roof/ceiling assembly and insulation types and configuration, relative to the requirements of 2016 CBC Section 1203.3 for"Unvented Attic& Unvented Enclosed Rafter Assemblies". We have revised roof/ceiling assembly detailing to convey how conformance to Section 1203.3 will be achieved at the Lofts. Please refer to Exhibit SK-A36.1 (attached). Please indicate by signing below, that our proposed approach to insulating MSC Loft's unvented roof/ceiling is acceptable to the City of Cupertino. � Best regards, Rocky Shen �,r��,1^�tUNITY L'E�.���C'�'�1E C�PERTINOEN _ A Best regards, Bu�L��NGqppROVED � `��; set of plans and specificalions(v1UST be kept at the � ��� � s'�.te d�uing corstr.:ction. It is unia�.�:ful to make any � , ,,.arges or al�,,-,a^io�saoff same. °�.d�,tlOffiaiae. = =,t•�m wd�r,u ��P ; HqLL NCT � Rocky Shen ��- ,,�n and s,c�� ' S Principal, AIA �� , " ,� ,, �r t.� be an '�,� r^ .� , �he ��o�at��on � .I � c� ;. L3';:. DNA Design And Architecture �it ���+, . �� r z `Y ,,r�as,crs ��Y Y — -.��^=��r��Y__ �''� _ /_-_r� r � -- " -_ ��6l�__ __ -- �<� iT � _._/31�- Albert Salvador Building Official � � � � � � ���� City of Cupertino, Building Division „� attachment Page 1 CHAPTER12 INTERIOR ENVIRONMENT SECTION 1201 I2031.1 Openings into attic. Exterior openings into the GENERAL attis space of any buifding intended for human occupancy 1201.1 Scope. The provisions of this chapter shall govem shall be protected to prevent the entry of birds, squir[els, ventilation, temperature control, lighting, yatds and coutls, rodents, snakes and other similar creatures. Openings for sound transmission, room dimensions, surrounding materials �'entilation having a least dimension of not less than '/16 and rodent proofing associated �vith the interior spaces of ���h(I.6 mm)and not more than '/a inch(6.4 mm)shall be buildings. permitted. Openings for ventilation having a least dimen- sion larger ihan '/� inch (6.4 mm) shall be provided with corrosiomresistant wire cloth ssreening, hardware clolh, SECTION 1202 perforated vinyl or similar material�vith openings having a DEFINITIONS least dimension oC not less than '/16 inch (1.6 mm)and not 1202.1 General. The follo���ing terms are deGned in Chapter more than '/� inch (6.4 mm). Where combustion air is z: obtained from an attrc area, it shall be in aeco�dance with Chapter 7 otihe C�liJornin Mechnnicn!Code. SUNROOM. 12033 Unvented attic and um�ented enclosed rafter THERMAL ISOLATION. assemblies. Unvented attics and unvented enclosed roof framing assemblies created by ceilings applied directly to the underside of the roof framing members/rafters and the struc- SECTION 1203 �ural roof sheathing at the top of[he roof framing members VENTILATION shall be permitted where all the following conditions are met 1203.1 General. Buildings shall be provided with natural �. The unven�ed attic space is complelely within the ventilatio�i�accocdance with Sectioo 1203.4,or mechanical building thermal em•elope. ventilatio� in accurdance with the Cn(rjornin Mechnnicn! Code. 2. No interior Class I vapor reta�decs are i�s[alled on the � ceiling side (attic tloor)of the unvented attic assembly � 1203.2 Ventilation required. Eoclosed attics and e�closed or on the ceili�g side of the unvented enclosed roof rafter spaces formed where ceilings are applied directly to the framing assembly. underside of roof framing members shall have cross ventila- tion for each separate space by ventilation openings protected 3. 1Vhere wood shingles or shakes are used,a minimum '�',- against the entwnce of rain and snow. Bfocking and bridging inch (6A mm) vented airspace separates the shingles or shall be arranged so as not to interfere�eith the movement of shakes and the roofing underlayment above the stn�o- aic An airspace of not less[han 1 inch(25 mm)shall be pra Wral sheathing. ���,� �j 4 vided belween the insulation and the roof sheathing. The net �R free ventilating area shall be not less than '/isu of the area of 4, ln Climate Zones 14 and/6, any air-impermeable insu- I lation shall be a Class II vapor retarder or shall have a ihe space ventilnted. Ventilators shall be installed in accoo- Class IIl vapor retarder coating or covering in direct dance with manufacturer's installation instructions. contac[with the underside of ihe insulation. Exception: The net &ee cross-ventilation area shall be permitted to be reduced to '/;oo provided both of the fol- See !he Cnlijornin Energy Code, Figure l00.!-A — lowing conditions are met - Calrfornia Clinmte Zones. I I. In Climate Zones 14 aid /6, a Class I or II vapor 4.1. (HCD 7& HCD 1)!n Climate Zones!4 nnd retarder is instalfed on the warm-in-�vinter side of �6, a Class!or Class!/vnpor retarder shnl! [he ceiling. be Fns'talled on the indii'ec!]r ronditioner( spnce side of n!/ insuln�ion in nn anvenle�l 2. At least 40 percent and not more Ihan 50 percent of attic ivi�h an�-permeaGle insulalion, for con- the cequired venti�g area is provided by ventilators densatimi conh�ol. bcated in the upper portion of the attic or raRer space. Upper ventilators shall be located �ot more 5. Insulation shall be located in accordance with the fol- than 3 feet (914 mm) below the ridge or highest �o�ving: point of the space, measured vertically, with the bal- 5.1. Item �.Ll, 5.12, 5.13 or S.IA shall be met, ance of the ventilation provided by eave or comice depending on the air penneability of Ihe insula- vents. Where the location of wall or roof framing tion directly under the stmctural roof sheathing. members conflicts n�itl� the i�stallation of upper A�o insu/ntiun.rha/1 Ge reqriired n�hen roof�iles, I ventilators, installation more than 3 feet (914 mm) �vood shi»gles or �vood shakes, or any olher below the ridge or highest point of ihe space shall be roofing syslem asing batteiis and no continuous � permitted. tur�ler7ayme�n is insta(led. A cailint�otes under- 2016 CALIFORNIA BUILDING CODE 631 � � I � " ' Cup�ri6M1��:L105C.ALLRI4HT>RfSF.R\'ED..1:ce,sedF�)u•znP'ivloxonNorEs.ioi5n�.ec�nATlpmamnuol.i¢nxT6�eemrn�MitM1UBSC.No(mhneepreEu:uun oe d6tribmion awM1o�izat ANl'UNAUTH0R12ED REPRO�CITIOV Op OISTAIBGTION IS il\'IOLATIOV UF THE FEDERdLCOPYRIGHT,\CT AND THE pCESSF A4REE V EVT,A\D SUP�EQ TOCIVIL:V O CRI`.I6AL PE6ALTIEF TMEREUYDE0. INTERIOR ENVIRONMENT I lnpmenl shnl( be cansirlered�o e.rist i(shenth- 7naLE 7203.3 ing, raafing paper or any conlinuous layer �NSULATION FOR CONDENSATION CONTROL �]aVing CIIJPI"m I"n(P ojno more rhan one penn CLIMATEZONE MINIMUM R-VALUE OFAIR- 11nf�El'(l1e[�ly'Cf(/J M27�tOCf IS/Jl'2S2n7. IMPERMEABLE INSULATION' G-IS tile rootonty 0(none required) S.I.L Where only air-impermeable insula- tion is provided, it shall be applied 3-�5 R-5 in direct contact �i�ith Ihe underside /&2 R-10 of the structural roof shea�hing. /6 R-15 5.12. Where ai�-PelmOab�e insu�a[iOtl is a. Convibutes to, but does not supersede, fhermal resistance requiremenis provided inside the building thermal for aVic and mof assemblies in�he Culi(ornio Enei'g��Code. < envelope, it shall be installed in 1203.4 Undervtloor ventilatioa Thc space between the bot- accordance with Item 5.1. In addi- tom of the floorjoists and the earth under any building except tion to the air-permeable insula�ion spaces occupied by basements or cellars shall be provided installed directly below the stnic- u,]th ventilztion openings through foundation walls or exte- tural sheathing, rigid board or sheet rior walls. Such openings shall be placed so as to provide insulation shall be installed directly cross ventilation of the under-floor space. above the structural roof sheathing in accordance with the R-values in 1203.4.1 Openings tor under-floor ventilatiom The net Table 1203.3 for condensation con- area of ventilation openings shall be not less than l square trol. foot for each 150 square feet (0.67 m'- for each 100 m�)of cra�vl-space area. Ventilation openings shall be covered �J.3. Where both air-impermeable and for their heigh� and width with any of�he following mate- aio-pemieable insulation ace pro- riats, provided that the least dimension of the coveri�g vided, the air-impermeable insula- shall be not greater than '/� inch(6.4 mm): tion shall be applied in direct contact with the underside of the s�ructural �� Perfora�ed sheet metal plates not less Ihan 0.070 > roof shea�hing and shall be in accor- inch(L8 mm)thick. dance witl� the R-values in Table 2. Expanded sheet metal plates not less Ihan 0.047 inch 12033 for co�densation controL (L2 mm)thick. The aio-permeable insulatio� shall 3, Cast-iron grilles or gratings. be installed directly uoder the air- impermeable insulation. 4. Exiruded load-bearing vents. 5.1.4. Altemafively, sufticient rigid board 5. Hardware cloth of 0.035-inch (0.89 mm) wire or or shee[ insula�ion shall be installed heavier. directly above the struch�ral roof 6. Corrosion-resistant wire mesh,with the least dimen- sheathing to maintain the monlhly sion not greater than '/g inch(3.2 mm). average temperature of the undeo- I I side of the structural roof sheathing 1203.4.l.1 /SPCBJ Opening.s for ande�'Jlom' ventila- above 45°F (7°C). For calculation �ia�shrd!be not less thon / /z s�¢�rve feet (0./35 m=J purposes, an interior air temperature %m� each 15 linear J'ee! (7620 /inenr mm) oJ e.rterior of 68°F (20°C) is assumed and the �vnlL They shol! be covered vith con-osion-resistanl �vire mesh n�ith mesh openings no�less�Han�/�inch 6.4 exterior air temperature is assumed rttrnJ nor�ittore than �/,inch(13 mm)in any dimensiore. to be the monthly average outside air temperature of the three coldest 1203.4.2 Exceptions. The following are exceptions to months. Sections 1203.4 and 1203.4.1: 5.2. N'here pre(ormed insulation board is used as the L Where warranted by climatic conditions,ventilation I air-impeivneable insulation layer, it shall be openings to the outdoors are not required if ventila- sealed at Ihe perimeter of each individuai sheet tion openings to ihe interior are provided. interior surface to form a continuous layer. 2. The total area of ventilation openings is permitted to Exceptions: be reduced lo'/����of ihe undervfloor area where the ground sur(ace is covered with a Class I vapor L Section ]203.3 does not apply to special use stmc- retarder material and the required openings are hues or enclosures such as swimming pool enclo- placed so as ro provide cross ventilation of the sures, data processing ce�te�s, hospitals or art space. The installation of opewble louvers shall not galleries. be prohibited. 2. Sec[ion 1203.3 does not apply to enclosures in Cli- 3. Ventilation openings a�e not requi�ed where contin- I mate Zones 14 nnd/61hat are humidified beyond 35 uously operated mechanical ventilation is provided perce�t during the three coldest months. at a rate of I.0 cubic foot per minute(efm) for each 632 2016 CALIFORNIA BUIL�ING CODE , � I � I I I � 1 fM1 'UPSC .II.R�GHT>RFiERVED. iaaessedp " :- t" ..lo�.on¢ � eien::pANpursuammC.rn�zAgreememn"tM1CTPSC.pofunAerreprWun:on E .bu[oneu�h zai :\VYF\'AUTHORI2FOREPRODLCIlO\pROI5TftI0lTl0\ISA\'IOL1TbYOFTHE�EDE0.,ILCOPIH�GHTACTT\pTHELICE\iF :1GRFFMFNT.AYp N6�FCT TO CICIL.1YD C0.1MI!.:1L pEp'ALTIES THEREUkpER. . ALTERNATE MATERIALS ANQ METMODS / MODIFICATION FORM � COMIJ�UNI7Y DEVELOPNiENT DEPARTAIENT•BUILDING DIVISION � 703D0 TORRE AVENUE• CUPERTINO,CA 95074-3255 �'"z''� (408)777-3228• FAX (4D8) 777-3333• buiitlinq(a�cuDertino.oro CUPERTINO ❑ REQUEST FOR MODIFICATION OF CODE (CBC '104.10,CPC 104.8) � REQUEST FOR ALTERNATE MATERIAL, DESIGN OR METHO�OF CONSTRUCTION(CBC 104.1'I, CFC 104.9) O RE�UEST FOR HARDSHIP EXEMPTION OR EQUIVALENT FACILITATION(HEALTH AND SAFETY CDDE 19957) To apDl !or thi=_requesL comDlele seclionS t 2,8 3�ink or t e SITE q ADDRESS I "t S�� �w �K , I!G%'rS) APN DATE ! _!�_/„7 � ` Owner�ll��.Sr�'/++/v��Q/�[U��.���-I..�nt?'F.lw.l...+-"'��.'. PC#. . . ..q.. .. . . . TYDe .�t . p�.. . Atltlress . ....... .... ...._ . .__... .,._ ... , . ... Pertril#�I..��Y. ����.,_._ Stodes: "�.p���SI+��.YI�..T_ -. I � EmaJ . ...... . . . .... . .,.... Phone. ... . . ... .._... PLN# . .,y. )..... j�n..�.7._ OccupancY:F ��$ .F!..._.. � DepL/Drv. Vk��/ .4?'.Y_: FloorAree�16�J�6�..�f.). - ApplicaN ......_._.. ._...__........ ......._._.._..Tille......._.. ...___ . ��7 n .. ... ___.... , JobSUWs- 1'1:T����y� Occ. Load . . . Address . __. . . . ..._ ........_. ..__ _...... . ....... .... r.� n .{ Email.. .. .. .. Phone. ........ ._.,..... Use of Bltlg��.!. . f:_./..�.. . 'z I RE�UEST: For co0e mo.'fi:a6ons.p'sase sla1=Ii�e app:ica0le rotle repuiremenl ara ine exlenl o�reliel aesirea. For allemale reqoesls.slale t�s lype ol rystem � m osed an0 Eesi n n��e�lwds. Su�mil lens il nece=_sary w inislrsle re ues�. h��9im:al sheels or tlxla ma be aHachetl. . � .. t _ . . w - - � - '� �- . . . . . . ' ' ' ' ' �_ -'--'�� `��, r� 7 ' � "'i _ ' " C L � 1 �1'il.l � !/ . . . . � JUSTIFICATION/FINOINGSOPE�UIVALENCY: �orcotlemotliGca�ions,epplicanishallEamonz�ro�elhal CodeSection(s): � �i special,Intl�vvJual reasons e.lsl�hat make comp�2nro wltn�ne s�nc1 letler ol�he erdinarr.:e imprankai antl tMl � f�� �'+ _r q j equiv;lemy is provitleJ. Por altemete req��ests.a09�aN shel!tlemmslrale sui�abiii�y.slrergV,,epe:.Gve�ess,fre I � � i 7�,(�rl`l�V �`.p�•v t . � esislance.tlura�iiil ,szkl-am sanitalion Ina�is e uivmem io t�e cotle for a simJar�se. � Aflech addiGonal sheats if necessary. � �'-�'E /��-�� - { � , ; r 'I V Peiilion x ���/C`T� �( � ,?,I Rehev,•e �/ G ,`/1n/ � � /� Si nature. ........ ........__ .__. Posii . . ..« ! . Dat .._..4_.( -. B _....... 0� � .__....._ _.._. .Date 1 .�'` __ _._.. , ,.r �_ _ _ The Request is: GRANTED ❑ DEMED Depl Commenis: ��/ � �y� � � �� CCN01710N5 OF APPRCVAL� No.of tlems: ......_!._.........._.... -. Fee Due�.S._..__.._._............. I � � — j DafePaid: __._..._.... ...._ _.. � ReceiFl No.:_____.___........... — - Processetl qc__._. _____._..... ;� p.�. ! 1�� -_:'� / /�- ^ ,(' A / � /..../.� . ._ .Aaie�._.._. �( Bui:di�a OKcial:.. . •t! ...♦ -'.. *^. __...... PnM !'Lr/�C"' �..J(i L'V r%'11�L �/i� / �/! 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