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Home My WebLink About13120166 - AMMR24 January 2017 Albert Salvador Building Official City of Cupertino, Building Division 10300 Torre Avenue Cupertino, CA, 95014 Re: Roof Insulation at Main Street Cupertino Lofts, Permit # 13120166 Main Street Cupertino Loft Residences, Cupertino, CA Dear Albert, J, D E S IGN Suite 140 `I 2062 Business Center Drive Irvine, CA 92612 714.389.1890 AND ARCHITECTURE Cilf'ER INO jig v4 •'i Suilr!inq 0coartnent JAN 2 r tui% REVIEvv'E` r.)R Reviewed CODE COMPLIXNCE By , 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 Best regards, 71�1� Rocky Shen Principal, AIA DNA Design And Architecture Albert Salvador Building Official City of Cupertino, Building Division attachment Page 1 COMMUNITY DEVELOPMENT DEPARTMENT BUILDING DIVISION - CUPERTINO gPPROVED atihe This set of plans and specifications MUST be kept lob site es during alterations It is same forunlawul to make any to deviate Chang therefrom,lwithf ut s plan and sped h 3'r�ur'sdSHAOLLINOT The StarnG n 5''a1 of the violation ba held to Per—T"'. or to be an at VO'- , or State L3.4. of any provisions of any Gty 01"I BY bra...—_-- /� — DATE �'� PERMIT # OFFICE C®PN y CHAPTER12 INTERIOR ENVIRONMENT SECTION 1201 GENERAL 1201.1 Scope. The provisions of this chapter shall govern ventilation, temperature control, lighting, yards and courts, sound transmission, room dimensions, surrounding materials and rodent proofing associated with the interior spaces of buildings. SECTION 1202 DEFINITIONS 1202.1 General. The following terms are defined in Chapter 2: SUNROOM. THERMAL ISOLATION. SECTION 1203 VENTILATION 1203.1 General. Buildings shall be provided with natural ventilation in accordance with Section 1203.4, or mechanical ventilation in accordance with the California Mechanical Code. 1203.2 Ventilation required. Enclosed attics and enclosed rafter spaces formed where ceilings are applied directly to the underside of roof framing members shall have cross ventila- tion for each separate space by ventilation openings protected against the entrance of rain and snow. Blocking and bridging shall be arranged so as not to interfere with the movement of air. An airspace of not less than I inch (25 mm) shall be pro- vided between the insulation and the roof sheathing. The net free ventilating area shall be not less than I/Iw of the area of the space ventilated. Ventilators shall be installed in accor- dance with manufacturer's installation instructions. Exception: The net free cross -ventilation area shall be permitted to be reduced to I/3w provided both of the fol- lowing conditions are met: 1. In Climate Zones 14 and 16, a Class I or II vapor retarder is installed on the warm -in -winter side of the ceiling. 2. At least 40 percent and not more than 50 percent of the required venting area is provided by ventilators located in the upper portion of the attic or rafter space. Upper ventilators shall be located not more than 3 feet (914 mm) below the ridge or highest point of the space, measured vertically, with the bal- ance of the ventilation provided by cave or cornice vents. Where the location of wall or roof framing members conflicts with the installation of upper ventilators, installation more than 3 feet (914 mm) below the ridge or highest point of the space shall be permitted. 1203.2.1 Openings into attic. Exterior openings into the attic space of any building intended for human occupancy shall be protected to prevent the entry of birds, squirrels, rodents, snakes and other similar creatures. Openings for ventilation having a least dimension of not less than '/I6 inch (1.6 mm) and not more than 1/, inch (6.4 mm) shall be permitted. Openings for ventilation having a least dimen- sion larger than 1/4 inch (6.4 mm) shall be provided with corrosion -resistant wire cloth screening, hardware cloth, perforated vinyl or similar material with openings having a least dimension of not less than VD, inch (1.6 mm) and not more than I/, inch (6.4 mm). Where combustion air is obtained from an attic area, it shall be in accordance with Chapter 7 of the California Mechanical Code. 1203.3 Unvented attic and unvented enclosed rafter 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- tural roof sheathing at the top of the roof framing members shall be permitted where all the following conditions are met: 1. The unvented attic space is completely within the building thermal envelope. 2. No interior Class I vapor retarders are installed on the ceiling side (attic floor) of the unvented attic assembly or on the ceiling side of the invented enclosed roof framing assembly. 3. Where wood shingles or shakes are used, a minimum I/,- inch /,inch (6.4 mm) vented airspace separates the shingles or shakes and the roofing underlayment above the struc- tural sheathing. Col e1 t A4 4. In Climate Zones 14 and 16, any air -impermeable insu- lation shall be a Class II vapor retarder or shall have a Class III vapor retarder coating or covering in direct contact with the underside of the insulation. See the California Energy Code, Figure 100.1-A — California Climate Zones. 4.1. (HCD 1 & HCD 2) In Climate Zones 14 and 16, a Class I or Class 7I vapor retarder shall be installed on the indirectly conditioned space side of all insulation in an unvented attic with air permeable insulation, for con- densation control. 5. Insulation shall be located in accordance with the fol- lowing: 5.1. Item 5.1.1, 5.1.2, 5.1.3 or 5.1.4 shall be met, depending on the air permeability of the insula- tion directly under the structural roof sheathing. No insulation shall be required when roof tiles, wood shingles or wood shakes, or any other roofing SYstem using battens and no continuous underlayment is installed. A continuous under - 2016 CALIFORNIA BUILDING CODE 631 or dirigbu ti CA BSC. ALL RIGHTS R T]IO IZED REPROD Su ONORow DISiRMITTION IS A VIOILATI pu OFT E FEDERAL COPYR GD CA AND f iE LICF md„nion AGRE distribution . AND SUB ANT UNAUFN NDCRIRENR L PIRIA ONOR VEREUBUTION IS A VIOLATION OF THE NEDERALCOPVRIGHT qCf AND THE LICENSE AGREEMENT, AND 6UB1ECr TD CI VIL AND CRIMINAL PENALTIES THEREUNDE0. INTERIOR ENVIRONMENT layment shall be considered to exist if sheath- ing, roofing paper or any continuous layer having a perm rate of no more than one perm under the dry cup method is present. 5.1.1. Where only air -impermeable insula- tion is provided, it shall be applied in direct contact with the underside of the structural roof sheathing. 5.1.2. Where air -permeable insulation is provided inside the building thermal envelope, it shall be installed in accordance with Item 5.1. In addi- tion to the air -permeable insulation installed directly below the struc- tural sheathing, rigid board or sheet insulation shall be installed directly above the structural roof sheathing in accordance with the R -values in Table 1203.3 for condensation con- trol. 5.1.3. Where both air -impermeable and air -permeable insulation are pro- vided, the air -impermeable insula- tion shall be applied in direct contact with the underside of the structural roof sheathing and shall be in accor- dance with the R -values in Table 1203.3 for condensation control. The air -permeable insulation shall be installed directly under the air - impermeable insulation. 5.1.4. Alternatively, sufficient rigid board or sheet insulation shall be installed directly above the structural roof sheathing to maintain the monthly average temperature of the under- side of the structural roof sheathing above 45°F (7°C). For calculation purposes, an interior air temperature of 680F (200C) is assumed and the exterior air temperature is assumed to be the monthly average outside air temperature of the three coldest months. 5.2. Where preformed insulation board is used as the air -impermeable insulation layer, it shall be sealed at the perimeter of each individual sheet interior surface to form a continuous layer. Exceptions: 1. Section 1203.3 does not apply to special use struc- tures or enclosures such as swimming pool enclo- sures, data processing centers, hospitals or art galleries. 2. Section 1203.3 does not apply to enclosures in Cli- mate Zones 14 and 16 that are humidified beyond 35 percent during the three coldest months. TABLE 1203.3 INSULATION FOR CONDENSATION CONTROL CLIMATE ZONE MINIMUM R -VALUE OF AIR - IMPERMEABLE INSULATION' 6-15 tile roof only 0 (none required) 3-15 R-5 1&2 R-10 16 R-15 a. Contributes to, but does not supersede, thermal resistance requirements for attic and roof assemblies in the California Energy Code. 1203.4 Under -floor ventilation. The space between the bot- tom of the floorjoists and the earth under any building except spaces occupied by basements or cellars shall be provided with ventilation openings through foundation walls or exte- rior walls. Such openings shall be placed so as to provide cross ventilation of the under -floor space. 1203.4.1 Openings for under -floor ventilation. The net area of ventilation openings shall be not less than 1 square foot for each 150 square feet (0.67 mr for each 100 in) of crawl -space area. Ventilation openings shall be covered for their height and width with any of the following mate- rials, provided that the least dimension of the covering shall be not greater than 1/A inch (6.4 mm): 1. Perforated sheet metal plates not less than 0.070 inch (1.8 mm) thick. 2. Expanded sheet metal plates not less than 0.047 inch (1.2 mm) thick. 3. Cast-iron grilles or gratings 4. Extruded load-bearing vents. 5. Hardware cloth of 0.035 -inch (0.89 mm) wire or heavier. 6. Corrosion -resistant wire mesh, with the least dimen- sion not greater than r/B inch (3.2 mm). 1203.4.1.7 /SPCB/ Openings for under floor ventila- tion shall be not less than 1 r/z square feet (0.135 in) for each 25 linear feet (7620 linear mm) of exterior wall They shall be covered with corrosion -resistant wire mesh with mesh openings not less than r/T inch (6.4 mm) nor more than/, inch (13 mm) in any dimension. 1203.4.2 Exceptions. The following are exceptions to Sections 1203.4 and 1203.4.1: 1. Where warranted by climatic conditions, ventilation openings to the outdoors are not required if ventila- tion openings to the interior are provided. 2. The total area of ventilation openings is permitted to be reduced to Yl. of the under -floor area where the ground surface is covered with a Class I vapor retarder material and the required openings are placed so as to provide cross ventilation of the space. The installation of operable louvers shall not be prohibited. 3. Ventilation openings are not required where contin- uously operated mechanical ventilation is provided at a rate of 1.0 cubic foot per minute (cfm) for each 632 2016 CALIFORNIA BUILDING CODE IliCop ". CA BSC. ALL RIGNTS RESERVED. Aa BYSoun Windowon N"29,0016 u:nwo AM pummtm Uccm Agramentwith CA BSG No (unhertrymducaon ard'uuibuwnauihoriuf. ANYUNAUTHORIZEDREPRODUCTIONORDIMIBt ONISAVIOI nONOFMEFEDEMLMPTRIGMACr ANDTNELICENSE AGRF.EMEM. ANDSUBIECFTOCIVIL ANDCMMINAL PENALTIES mEREUNDER a N ALTERNATE MATERIALS AND METHODS / MODIFICATION FORM COMMUNITY DEVELOPMENT DEPARTMENT •BUILDING DIVISION 10300 TORRE AVENUE • CUPERTINO, CA 95014-3255 (408) 777-3228 • FAX (408) 777-3333 • building0cuoerlino.lb CUPERTINO ❑ REQUEST FOR MODIFICATION OF CODE (CBC 104.10, CFC 104.8) (i REQUEST FOR ALTERNATE MATERIAL, DESIGN OR METHOD OF CONSTRUCTION (CBC 104.11, CFC 104.9) ❑ REQUEST FOR HARDSHIP EXEMPTION OR EQUIVALENT FACILITATION (HEALTH AND SAFETY CODE 19957) ,v aPW u, vuo ra4ue SITE ppl K O�i,y APN DATE If _,Z_I� ADDRESS -1 SSo OwnertlJ=.tryrFJ.V.r. ./'fU�..n. �f.'l. Ld M..!•...l..f.'f-^v PC#: .......................... ........... Type: .......................... .....p..C. Address._..............._....................................._...._........_._........................................... Permit#: �.[.�.K..Q.l L..l2....... Stories: 4..�o.. .. (+��:.Y.A{ Email. ............................... ....... .......... Phone.................... I..................... PLN #:........))..//..�l........r�..fftt..f�..II... Occupancy: �1.,...Y...... Dept./DIv..A..It.V. .JAN.Y.' Floor Area:l.�'3l... Applicant......... _......................._............................. Title ........................... ................... '�,n,.� l� Job Status: _�'i.M.711 D. Occ. Load: ............................ Address.... ......... ..._..........................................................................._............... ......... Email ............................ ........ Use of BId9�L �....i �.. ......................................... Phone...................................... 2 1 REQUEST: For cols motluications, please `tate ere applicable code requirement and me extent of relief desired. For allemale requests. slate me type of sycem m osed and desi n methods. Submil Ions ii nacessarM illuslrale reuael. Additional sheels w data my be attached. 3 JUSTIFICATIONIFINDING$ OF EQUIVALENCY: Fwcode modificasore, appacard shalldemonstrate that spacial. Intlivitlual reasans exist that make mrnpliance with ft skid letter of the Ordinance im reckrel and Ihat ,?gWvelerYy b provided. For aaernate requests, applicant shell demonstrate suitability, strength, eflecrveness, fire reslstenca. dureblle , sa!ty are sanialbn That is eqoivaleffi to the code for a similar use. Code Section(s): �y -fl on P10 CVt' tj �� v Attach additional shyee-llss if necessary. i Petttio y yam. }� Si nature: ......... Post :.. 8( w! ,.,�.•Dat� , '� Revie I/1�/ �.......—Dater:..l.....j.'.1..I........ AI jm'nr_7015doc reldsed 07/OI715 22 SLOPE 3/8" PER F7, MIN I I I � II III I I I l i II NOTE: PROVIDE "L" MET. TRIM & FIRESTOP AT LOCATIONS WHERE DRAIN LEADERS PENETRATE ROOF/CLG. MEMBRANE. REFER TO 8/G303 FOR ADDITIONAL INFORMATION FOR THE PRIMARY 1 -HR. ROOF/CEILING ASSEMBLY (UNVENTED). tV *PER DET. 7, THIS SHEET. I 11 2'-6" MAX. SEE G.N. 06 /A106a & STRL. DWGs. IF GREATER THAN 30 -IN. SECTION DETAIL: INSULATION REVISION AT ROOF DRAINS (DET. 10/A811 REVISED) ROOF INSULATION LAYERS ARE REVISED IN CONFORMANCE WITH THE REQUIREMENTS OF 2016 CBC SECTION 1203.3 UNVENTED ATTIC & UNVENTED ENCLOSED RAFTER ASSEMBLIES. UNVENTED ROOF JOISTS OCCUR WITHIN THE BUILDING THERMAL ENVELOPE. NO CLASS I VAPOR RETARDERS WILL BE INSTALLED ON THE CEILING SIDE. THE PROJECT IS WITHIN CLIMATE ZONE 4. MONTHLY AVERAGE OUTSIDE AIR TEMPERATURE OF THE THREE COLDEST MONTHS IS 50.3 DEGREES F. OVERFLOW DRAIN ASSEMBLY (22.07): 2" HIGH RING OCCURS O/FLOW DRAIN ONLY. PRIMARY DRAIN ASSEMBLY. SLOPE DRAIN PAN PER DET. 7, THIS SHEET. HOT-AIR WELD PER MFR. SINGLE PLY ROOFING SYSTEM (07.04). F.R. RATED GYPSUM ROOF BOARD (07.06). TAPERED POLYISO ROOF INSULATION (07.03); >R-5 / 1 -IN. THICKNESS; AIR -IMPERMEABLE MFR. FASTENERS & STRESS PLATES PER MFR. REQ. NON -REINFORCED MEMBRANE I I I I I I FLASHING 0/ FIELD TAPERED INSULATION (ATTACHED PER ROOF MEMBRANE MFR. REQ.) I TO PROVIDE GRADUAL \ TRANSITION AT SUMP w/ SLOPE UNDER DECK CLAMPS w/ BLOCKING AS REQ. ENCLOSED ATTIC / VOID SPACE 8B: 1 -HR. RF./CLG. (UNVENTED) w/ ENCLOSED SPACE ABV. (SEE BLW. FOR NOTES NOT IDENTIFIED HERE) i J1(_/I`y BA: 1 -HR. ROOF/CLG. (UNVENTED) AT EXT. ROOFING SYSTEM METAL DRAIN ASSEMBLY PAN WITH SIDE OUTLET. INFILL JOIST CAVITY AROUND DRAINS & LEADERS w/ CLOSED CELL SPRAY FOAM INSULATION (07.02); AIR -IMPERMEABLE; R-30 AT 6 -IN. INFILL REMAINING w/ UNFACED G.F.B. INSULATION (07.01); AIR -PERMEABLE. WOOD FRMG. PER STRL. DWGs; PERPENDICULAR LADDER FRMG. MAY OCCUR (SHOWN DASHED). DOUBLE WOOD FLOOR OF A TYPE & THICKNESS THAT CONFORMS TO THE CODE SECTION LISTED UNDER "F.R. RATING" BELOW & CONFORMS TO STRL. DWGs; ONLY OCCURS WHERE ENCLOSED SPACE ABOVE IS USABLE OR WHERE EXT. CEMENT PLASTER SYSTEM (09.01) OCCURS IN LIEU OF LAYERS OF GYP. SHTG. SINGLE PLY ROOFING SYSTEM (07.04). GYPSUM ROOF BOARD (07.06). TAPERED POLYISO ROOF INSULATION (07.03); AIR - IMPERMEABLE* WOOD NAILERS / BLKG.: ATTACHED AT 250 LBS/FT.; T.O. NAILERS TO FOLLOW ADJACENT ROOF SLOPES. / 1 ; EXT. GRADE WD. ROOF SHTG. (06.02) ��` --- G.F.B. ACOUSTICAL INSULATION (07. MIN. APPLY AIR - PERMEABLE E INSULATION TO UNDERSIDE OF ROOF SHTG. F.R. RATING = 1 -HR. 8A: GA FILE NO. RC2601 (SIM.) 8B: 2010 CBC TABLE 720.1(3)13-1.2 (FOOTNOTES M & N). *NOTE: THIS PROJECT IS IN CLIMATE ZONE 4. WHERE PREFORMED INSULATION BD. IS USED AS THE AIR - IMPERMEABLE INSULATION LAYER, IT SHALL BE SEALED AT THE PERIMETER OF EACH INDIVIDUAL SHEET INTERIOR SURFACE TO FORM A CONTINUOUS LAYER. ROOF FRAMING: 2x10 MIN. CONVENTIONAL WOOD FRMG. (06.01) AT 16" O.C. (TYP.). (2) LAYERS 5/8" F.R. RATED GYP. BD. (09.08) AT INTERIOR CONDITIONS, OR GYP. SHTG. (09.07) AT EXT. CONDITIONS. NO INTERIOR CLASS I VAPOR RETARDERS ON CLG. SIDE. SECTION DETAIL: INSULATION REVISION AT PRIMARY ROOFS (DET. 8/G303 REVISED) MAIN STREET CUPERTINO LOFTS RESIDENCES 19550 VALLCO PARKWAY, CUPERTINO, CA 95014 TITLE: SECTION DETAILS: PROPOSED INSULATION REVISION FOR UNVENTED FLAT ROOF/ CEILING ASSEMBLY SCALE: N.T.S. CITY PERMIT NO: 13120166 2062 Business Center Drive Suite 140 , Irvine, CA 92612 714.389.1890 [) DESIaN AND ARCHITECTURE OWNER: MAIN STREET CUPERTINO AGGRIGATOR, LLC. 288 SAND HILL ROAD SUITE 241 MENLO PARK, CA 94025 TAKEN FROM DRAWING: 6303, A811. 06.22.15 CONSTRUCTION SET PART OF REVISION / DELTA:Q DATE SK- ISSUED: 01.24.2017 BY: D.JENKINS SK- PAGE: SK -A36.1 DQA ONA DESIGN AND ARCHRECNRE EXPRESSLY RESEM M COUNDN UW COPYIMM AND MER PRO M RGNR COMMD IN MSE DOCUQNIS. THEY DRN&NR AAE NOR TO K &TEAR URCOUCED OR DS TMD N MN FORM OR MW[R WMISIfIER NOR NS R TO K ASSAID TO ANY THIRD Po . WIIHOUI FIRST WANING EXIN&SS MEN CONSENT OF DNA DESIGN AND ARCHITECTURE.