Answers & Opinions

The Council's Policies and Procedures, in WAC 51-04-060, allows the Council to issue opinions (interpretations) relating to the codes at the request of a local or state official, or their designee, responsible for implementation and enforcement of the specific code provision on which the opinion (interpretation) is requested. For the Council to provide a formal opinion (interpretation), a letter requesting the opinion (interpretation) needs to be submitted by a code official. The final opinions (interpretations) of the Council are advisory only. Opinions (interpretations) that have been finalized are provided through the links to the left.

Some of the opinions (interpretations) refer to illustrations, diagrams, and attached documentation. These supporting documents are not posted on the Web. If you would like a copy of a supporting document please request it from Council Staff.

Year Interpretation Number Code Section Number Code Edition
2020 20-09 C403.1.3, Data Centers WA State Energy Code-Commercial 2018
2020 20-08 601.2, Air movement in corridors International Mechanical Code 2015
2020 20-08 1020.5 International Building Code 2015
2020 20-07 2018 IRC 506.2.3; AF103.3 International Residential Code 2018
2020 20-06 403.4 International Mechanical Code 2018
2020 20-05 C406 WA State Energy Code-Commercial 2018
2020 20-04 C403.1.1 WA State Energy Code-Commercial 2018
2020 20-03 C405.2.5 WA State Energy Code-Commercial 2015
2020 20-03 1008 International Building Code 2015
2020 20-02 IRC 1307.3 International Residential Code 2015
2020 20-02 UPC 507.13 Uniform Plumbing Code 2015
2020 20-02 WSEC C404.5 and R403.5.5 WA State Energy Code-Residential 2015
2020 20-01 Chapter 4 International Mechanical Code 2015
2020 20-01 1109 International Building Code 2015
2020 19-06 907.2.9, manual fire alarm systems International Fire Code 2015
2020 19-05 427, Electric vehicle charging infrastructure International Building Code 2015
2019 19-07 1705 Mass Timber Special Inspections International Building Code 2015
2019 19-04 Table R406.2, Additional efficiency credits WA State Energy Code-Residential 2015
2019 19-03 703 Mass Timber Fire Resistance Rating International Building Code 2015
2019 19-02 1104, Access to Mezzanines International Building Code 2015
2019 19-01 C402.5.6, Loading dock weatherseals WA State Energy Code-Commercial 2018
2018 18-14 WAC 51-50-007 International Fire Code 2015
2018 18-13 WSEC C407. 5.1 Tables 2&3 WA State Energy Code-Commercial 2015
2018 18-12 WSEC 404.9 WA State Energy Code-Commercial 2015
2018 18-11 WSEC C405.7 WA State Energy Code-Commercial 2015
2018 18-10 404.4/502.14 Automobile Repair Facilities International Mechanical Code 2015
2018 18-09 Table R406.2, Energy Credits - EF vs. UEF WA State Energy Code-Commercial 2015
2018 18-08 C403.2.7.1/C403.2.6 / IMC 507 Kitchen hoods International Mechanical Code, WA State Energy Code-Commercial 2015
2018 18-08 C403.2.7.1/C403.2.6 / IMC 507 Kitchen hoods International Mechanical Code, WA State Energy Code-Commercial 2015
2018 18-08 IMC 507 / WSEC C403.2.6, C403.2.7.1 International Mechanical Code 2015
2018 18-07 ANSI A117.1, 405, Ramps International Building Code 2015
2018 18-07 Ch. 11/ANSI A117.1 405, Ramps International Building Code 2015 IBC (2009 A117.1)
2018 18-06 C403.6, DOAS / IMC 403 WA State Energy Code-Commercial 2015
2018 18-06 WSEC C403.6, IMC 403, DOAS systems International Mechanical Code 2015
2018 18-05 C403.6, DOAS WA State Energy Code-Commercial 2015
2018 18-04 R403.7.1, Electric resistance heat WA State Energy Code-Residential 2015
2018 18-03 2902.1 Min. Required Plumbing Fixtures at Storage Occupancy International Building Code 2015
2018 18-02 1010, Door Locks & Hardware International Building Code 2015
2018 18-01 503.1 Fire walls International Building Code 2015
2017 17-25 C403.2.6.3/C403.6 Ventilation controls & DOAS WA State Energy Code-Commercial 2015
2017 17-24 R310 Emergency escape & rescue openings International Residential Code 2015
2017 17-23 504 Stairway pressurization in Type VA bldgs. International Building Code 2015
2017 17-22 IEBC 705.1.9, Toilet rooms International Building Code 2015
2017 17-21 R202, Def. of Residential in relation to accessory bldgs. WA State Energy Code-Residential 2015
2017 17-20 1020/3006 Hoistway venting in residential rated corridors International Building Code
2017 17-19 R202 Habitable attic International Residential Code
2017 17-18 3006.2 Hoistway opening protection International Building Code
2017 17-17 510.2 Height increase for I-1, Cond. 2 occupancies International Building Code
2017 17-16 304/2902 Toilet facilities in car wash International Building Code
2017 17-15 M1507 Ventilation openings International Residential Code
2017 17-14 312 Occupancy classification / Greenhouse International Building Code
2017 17-13 IEBC/IFC 1104.1, Means of egress in existing bldgs. International Fire Code
2017 17-13 IEBC/IFC 1104.1 Means of egress in existing bldgs. International Building Code
2017 17-12 R311 Means of Egress International Residential Code
2017 17-11 IFC 105.7.3, 105.6.9 International Fire Code
2017 17-10 504.3 Building Height & Number of Stories/CLT International Building Code
2017 17-09 C403.6, DOAS WA State Energy Code-Commercial
2017 17-08 C404.7.1, Circulation systems WA State Energy Code-Commercial
2017 17-07 C404, C503.5, Service water heating WA State Energy Code-Commercial
2017 17-06 C406.7, Service water heating WA State Energy Code-Commercial
2017 17-05 C406.7, Service water heating WA State Energy Code-Commercial
2017 17-04 C406.4, Lighting controls WA State Energy Code-Commercial
2017 17-03 C406.1.1, Tenant spaces WA State Energy Code-Commercial
2017 17-02 C406, Additional efficiency package options WA State Energy Code-Commercial
2017 17-01 105 Permits International Building Code
2016 16-14 Table R406.2 WA State Energy Code-Residential
2016 16-13 Table R406.2 WA State Energy Code-Residential
2016 16-12 IBC  1107.3 Accessible Spaces; 1110.2 Facilities serving Group R-2 International Building Code
2016 16-11 Table R301.5 Minimum Uniformly Distributed Live Loads International Residential Code
2016 16-10 IBC 427.1/Scope; 427.4/Electric Vehicle charging Infrastructure International Building Code
2016 16-09 IBC 427.1/Scope; 427.2 Electrical vehicle charging infrastructure International Building Code
2016 16-08 R402.2.7, Floor insulation WA State Energy Code-Residential
2016 16-07 R302.3  Wall continuity International Residential Code
2016 16-06 IFC 916/Alerting Systems International Fire Code
2016 16-05  IEBC IEBC Chapter 13/Moved Buildings International Building Code 2015
2016 16-04 M1505  Exhaust hoods International Residential Code 2015
2016 16-03 Table 2902.1/Minimum number of fixtures International Building Code 2015
2016 16-02 R309.2  Carports International Residential Code 2012
2016 16-01 2909.2.1 International Building Code 2012
2015 15-12 IBC 310.4/420.6/1018.6/Smoke barriers in assisted living International Building Code
2015 15-11 IBC 2902.3.1 Access to toilet rooms International Building Code
2015 15-10 IFC 3800 Marijuana processing/extraction facilities (emergency rule) International Fire Code
2015 15-09 IFC 5606.4/Black powder; 5604.2 Smokeless propellants; International Fire Code
2015 15-07 IFC Chapter 2/ Section 307.5--Sky lanterns International Fire Code
2015 15-06 IBC 504.3 Stair enclosure pressurization increase International Building Code
2015 15-05 IBC/308.3.3/IRC R325 - Adult Family Homes International Building Code
2015 15-04 IBC - WAC 51-50-007 Temporary Growing Structures International Building Code
2015 15-03 IBC 311.2/IFC 903.2.9 Fire sprinklers in S-1 mini storage International Building Code
2015 15-03 IBC 311.2/IFC 903.2.9 Fire sprinklers in S-1 mini storage International Fire Code
2015 15-02 IBC 503, 508.4.2 Area limitation in mixed use bldgs. International Building Code
2015 15-01 IBC 3109.4/IRC AG105.2 Pool barriers International Residential Code
2015 15-01 IBC 3109.4/IRC AG105.2 Pool barriers International Building Code
2014 14-23 C402.4.7 Vestibules WA State Energy Code-Commercial
2014 14-22 IBC 1208.3 Room area; 1208.4 Efficiency Dwelling Units International Building Code
2014 14-21 IBC 1013.6 Mechanical equipment; [B]304.11 Guards International Building Code
2014 14-20 IFC 605.11.3, Access and Pathways International Fire Code
2014 14-19 C403.3.1 Economizers WA State Energy Code-Commercial
2014 14-18 C402.4.5.2, C403.2.4.4 Dampers WA State Energy Code-Commercial
2014 14-17 C402.4.5.2 Dampers WA State Energy Code-Commercial
2014 14-16 C402.4.1.2.3 Air leakage WA State Energy Code-Commercial
2014 14-15 C405.2.3 Lighting controls WA State Energy Code-Commercial
2014 14-14 Refrigerated space definition WA State Energy Code-Commercial
2014 14-13 C402.3.1.3 Window limit WA State Energy Code-Commercial
2014 14-12 C409 Metering WA State Energy Code-Commercial
2014 14-11 C407.5.1 On site renewable energy WA State Energy Code-Commercial
2014 14-10 R102.7.2 Moved Buildings International Residential Code
2014 14-09 IFC 1103.7, 1103.7.1, Table 1103.1 Emergency Voice Alarm International Fire Code
2014 14-08 Tables A105.1 Default U-factors for floors WA State Energy Code-Commercial
2014 14-07 Semi-heated building definition WA State Energy Code-Commercial
2014 14-06 C101.5.2 Low energy buildings WA State Energy Code-Commercial
2014 14-05 C402.4.7 Vestibules WA State Energy Code-Commercial
2014 14-04 C402.5, C402.6 Coolers/freezers WA State Energy Code-Commercial
2014 14-03 C403.2.10.3 Fan motors WA State Energy Code-Commercial
2014 14-02 C101.4.3.2, C403.2.10 Fan motor efficiency WA State Energy Code-Commercial
2014 14-01 C101.4.3, C402.4.1.2.3 Air leakage WA State Energy Code-Commercial
2013 13-16 C402.4.7 Vestibules WA State Energy Code-Commercial
2013 13-15 R403.4.2 Pipe insulation WA State Energy Code-Residential
2013 13-14 IFC/IBC 903.2.3 Portable school classrooms International Building Code
2013 13-14 IBC/IBC 903.2.3 Portable school classrooms International Fire Code
2013 13-13 IBC 2902.1 Plumbing fixture count International Building Code
2013 13-12 IBC 1204.1 Temperature control International Building Code
2013 13-11 C409.3  End use metering WA State Energy Code-Commercial
2013 13-10 IBC 3002.4 Elevator requirements International Building Code
2013 13-09 C403.2.2  HVAC sizing WA State Energy Code-Commercial 2012
2013 13-08 IFC/IBC 908.7 Carbon Monoxide Alarms International Building Code 2012
2013 13-08 IFC/IBC 908.7 Carbon monoxide alarms International Fire Code 2012
2013 13-07 IBC 308.2/310.1 Classification of assisted living facilities International Building Code 2009
2013 13-07 IBC 308.2/310.1 Classification of assisted living facilities International Fire Code 2009
2013 13-06 R101.2 Mixed occupancy scoping International Residential Code 2009
2013 13-06 IBC/IRC 101.2 Mixed occupancy building scoping International Building Code 2009
2013 13-05 R101.2 Sprinkler requirements International Residential Code 2012
2013 13-04 IBC 1509.7 PV panel fire classification International Building Code 2012
2013 13-03 IFC 404.3.3 Lockdown plans/IFC 915 Alerting systems International Fire Code 2009
2013 13-02 R403 Footings International Residential Code 2009
2013 13-01 404.4, Automotive repair facilities International Mechanical Code 2009
2012 12-02 IRC 315.2 and IFC 4603.8 - Existing dwellings - deadline for compliance International Fire Code
2012 12-02 R315.2  Existing Dwellings - Deadline for compliance International Residential Code
2012 12-01 IBC/IFC 908.7 Carbon Monoxide Alarms International Building Code
2012 12-01 IFC/IBC 908.7 Carbon Monoxide Alarms International Fire Code
2012 12-01 R315.2 Carbon Monoxide Alarms in Dormitories International Residential Code
2011 11-20 IBC 3410.1 Moved Buildings International Building Code
2011 11-20 R102.7.2 Moved Buildings International Residential Code
2011 11-19 503.8.1, Ductless Heat Pump Thermostatic Controls WA State Energy Code-Residential
2011 11-18 Chapter 45, Marinas International Fire Code
2011 11-16 1202, Whole Building Energy Metering WA State Energy Code-Commercial
2011 11-15 Table 12-1, Metering Thresholds WA State Energy Code-Commercial
2011 11-14 1132, 1203 Energy Metering, existing building WA State Energy Code-Commercial
2011 11-13 1203, Energy Metering, existing building WA State Energy Code-Commercial
2011 11-12 Chapter 12, Energy Metering WA State Energy Code-Commercial
2011 11-11 Chapter 12, Energy Metering WA State Energy Code-Commercial
2011 11-10 1203, Energy Metering, core & shell bldg. WA State Energy Code-Commercial
2011 11-08 IFC 907.2.9, Carbon Monoxide Alarms International Fire Code
2011 11-07 Tables 13-1/13-2, 1009 Mass Walls WA State Energy Code-Commercial
2011 11-06 1132.2 Existing Building Mechanical Systems WA State Energy Code-Commercial
2011 11-05 IBC 903.2.3 Group E sprinklers International Building Code
2011 11-05 903.2.3 Group E Sprinklers International Fire Code
2011 11-04 503.10.1 Ducts WA State Energy Code-Commercial
2011 11-03 502.4.5 Building Air Leakage Testing WA State Energy Code-Commercial
2011 11-02 505.1 Interior Lighting WA State Energy Code-Commercial
2011 11-01 R403.1.3 Lap Splices International Residential Code
2010 10-05 IRC Table M1508.3, IMC Table 403.8.5.1 International Residential Code
2010 10-05 IMC Table 403.8.5.1, IRC Table 1508.3 International Mechanical Code
2010 10-03 IFC 907.2.9, Carbon Monoxide Alarms International Fire Code
2010 10-02 IBC 101.2, 310.1, IRC 101.2, Transient Housing R-1 status International Building Code
2010 10-01 IRC AS107.1, Fire Sprinklers International Residential Code
2009 09-03 IFC 3301, Explosives International Fire Code
2009 09-02 IBC 903.2.1.6, IFC 903.6.2 International Building Code
2009 09-02 IBC 903.2.1.6, IFC 903.6.2 International Fire Code
2009 09-01 IRC R307, UPC 407.6, 411.7 International Residential Code
2009 09-01 IRC R307, UPC 407.6, 411.7 Uniform Plumbing Code
2008 08-09 IBC/IFC 202, 903.2.1.6  Nightclubs International Fire Code
2008 08-09 IBC/IFC 202, 903.2.1.6  Nightclubs International Building Code
2008 08-08 IFC 2206.7  Ethanol fuel dispensing stations International Fire Code
2008 08-07 IBC 2902.3.1, 2903.4.1, Plumbing fixture calc International Building Code
2008 08-06 M1307, G2408, Elevation of ignition source International Residential Code
2008 08-05 Table 11-1, Economizer Options for Existing Buildings WA State Energy Code-Commercial
2008 08-04 608.7, Vaccuum relief valves Uniform Plumbing Code
2008 08-03 R403.1.6, Foundation anchorage International Residential Code
2008 08-02 R602.10.11.1, Braced wall lines International Residential Code
2008 08-01 3409, Existing Buildings International Building Code
2008 08-01 IBC 2902.2.1, 3409.7, Plumbing fixture calculation International Building Code
2007 07-08 2006 IRC Section R403.1.6.1, Foundation anchorage International Residential Code
2007 07-07 2006 IRC Appendix F/VIAQ, Hierarchy of codes re: radon International Residential Code
2007 07-06 2006 IRC Appendix F, Radon mitigation International Residential Code
2007 07-05 IBC/IFC 903.2.2, Portable classrooms International Fire Code
2007 07-05 IBC/IFC 903.2.2, Portable classrooms International Building Code
2007 07-04 2006 IRC Section M1501.1, Exhaust fans International Residential Code
2007 07-04 International Mechanical Code
2007 07-03 1423, Economizers WA State Energy Code-Commercial
2007 07-02 2006 IRC Appendix F, Radon mitigation International Residential Code
2007 07-01 2006 IRC Section R703.1, Water resistive barrier International Residential Code
2006 06-04 1120 and 1310  Outdoor heaters WA State Energy Code-Commercial
2006 06-03 2003 IBC Section 3408.1 / IRC Section R102.7.2 moved bldgs International Residential Code
2006 06-03 IBC 3408.1 / IRC R102.7.2 moved bldgs (2003) International Building Code
2006 06-02 IFC 903.2.2 / IBC 3403, 3406 and 903.2.2 International Fire Code
2006 06-02 IFC 903.2.2/IBC 3403, 3406 and 903.2.2 (2003) International Building Code
2006 06-01 2003 VIAQ 502.1.2 / 2003 IRC 408.2 Crawlspace ventilation International Residential Code
2005 05-01 IBC 3403.1 / IFC 903.2.1.2 Sprinklers in existing bldgs International Fire Code
2005 05-01 IBC 3403.1 / IFC 903.2.1.2 sprinklers in existing bldgs (2003) International Building Code
2004 04-05 Group A Occupancies, Section 1103.1.2.1 (Religious facilities) International Building Code
2004 04-04 Applicability of previous interpretations Uniform Plumbing Code
2004 04-01 IBC 313.8.2.1, Fire sprinkler systems in LC Occupancies (2003) International Building Code
2003 03-02 603.3.3, Backflow Assembly Testing Uniform Plumbing Code
2003 03-01 1104.1, Areas of Evacuation Assistance International Building Code
2002 02-14 WA State Energy Code-Commercial
2002 02-12 1433, Economizers, Mechanical Room Exception (2001 Code) WA State Energy Code-Commercial
2002 02-11 1413.4, Humidification (2001 Code) WA State Energy Code-Commercial
2002 02-10 1413, Economizers (2001 Code) WA State Energy Code-Commercial
2002 02-09 1452, Pool Water Heaters (2001 Code) WA State Energy Code-Commercial
2002 02-08 1412.4.1, Motorized Dampers (2001 Code) WA State Energy Code-Commercial
2002 02-07 1411.1, Definition of Furnace (‘01 Code) WA State Energy Code-Commercial
2002 02-06 1301, Applicability to ATM enclosures (2000 Code) WA State Energy Code-Commercial
2002 02-05 1103.2.2, Accessible Route of Travel International Building Code
2002 02-04 1107.3, Signs International Building Code
2002 02-03 Interps Applicable to the 2001 WSEC WA State Energy Code-Commercial
2002 02-02 Interps Applicable to the 2000 WSEC WA State Energy Code-Commercial
2002 02-01 Sections 1111 and 1112, Additions and Alterations International Building Code
2001 01-10 1105.4.9  Alarms International Building Code
2001 01-09 1105.4.9, Exception 3  Alarms International Building Code
2001 01-08 UBC 310.6.1 ex. 3 and 313.6.1 ex. 3, Ceiling heights (1997) International Building Code
2001 01-06 1997 UMC 1104.3.2, Ventilated Spaces International Mechanical Code
2001 01-05 UBC 313, LC Occupancies (1997) International Building Code
2001 01-04 1411.4, Packaged Electric Heating & Cooling Equipment WA State Energy Code-Commercial
2001 01-03 1109, Accessibility of Existing Buildings International Building Code
2001 01-02 1103.1.1, Exception 1, Accessibility of Equipment Shelters International Building Code
2001 01-01 1106.11, Fixtures for Use by Children International Building Code
2000 00-17 1111, 1112, Alteration of Existing Facilities International Building Code
2000 00-16 1107.2.5, "Firm and Stable" surface International Building Code
2000 00-15 Chapter 11, Labeling of Refrigerant Piping International Mechanical Code
2000 00-13 Table 14-5, Insulation of Return Air Ducts WA State Energy Code-Commercial
2000 00-12 1107.1.4, Parking for Group R International Building Code
2000 00-11 1104, Areas of Evacuation Assistance, Garages International Building Code
2000 00-10 1109, Existing Buildings International Building Code
2000 00-09 1106.11, Bathroom Facilities International Building Code
2000 00-07 1103.2.2, 3000 sq ft Exemption International Building Code
2000 00-06 301, Standards and Alternates Uniform Plumbing Code
2000 00-05 1106.11.10, 1106.27,  Shower Stalls International Building Code
2000 00-04 1104.2.1, Areas of Evacuation Assistance International Building Code
2000 00-03 Applicability of Previous Interpretations International Building Code
2000 00-03 Applicability of Previous Interpretations International Building Code
2000 00-02 1105.4.9, Audible and Visible Alarms International Building Code
2000 00-01 901.4, Unvented Decorative Gas Logs International Mechanical Code
1999 99-15 1106.15 and UFC 1007.2.12.10, Visible Alarms International Building Code
1999 99-15 UFC 1007.2.12.10, Visible Alarms International Fire Code
1999 99-14 1102, Path of Travel International Building Code
1999 99-13 UBC Chapter 29 and Table 29-A, Minimum Plumbing Fixtures International Building Code
1999 99-12 WA State Energy Code-Commercial
1999 99-11 Chapter 11, Applicability to Amusement Parks International Building Code
1999 99-09 Applicability of Previous Interpretations International Mechanical Code
1999 99-08 1412.2 and 1412.5, Heat Pumps WA State Energy Code-Commercial
1999 99-07 Applicability of Previous Interpretations Uniform Plumbing Code
1999 99-06 1103.1.2.1, Religious Facilities International Building Code
1999 99-05 1107.7, Parking International Building Code
1999 99-04 UBC 313, LC Occupancies International Building Code
1999 99-03 1106.15, Visible Alarms International Building Code
1999 99-02 UBC Chapter 29 and Table 29-A, Minimum Plumbing Fixtures International Building Code
1999 99-01 201, Definition of Small Business WA State Energy Code-Commercial
1998 98-17 UBC Chapter 29, Table 29-A, Minimum Plumbing Fixtures International Building Code
1998 98-16 Chapter 51-04 WAC, Adoption of Code Appendices International Fire Code
1998 98-16 Chapter 51-04 WAC, Adoption of Appendices International Mechanical Code
1998 98-16 Chapter 51-04 WAC, Adoption of Code Appendices Uniform Plumbing Code
1998 98-13 UBC 1004.3.4.5. Exception 4 International Building Code
1998 98-12 608.5 Exception, Relief Valve Drains Uniform Plumbing Code
1998 98-11 UBC 313, LC Occupancies International Building Code
1998 98-10 1105.4.8 and 1106.3 International Building Code
1998 98-08 5201.1, Fleet Fueling International Fire Code
1998 98-07 1312.18, Fuel Gas Pipe Labeling International Mechanical Code
1998 98-06 1002.2, Using Water for Space Heating International Mechanical Code
1998 98-05 UBC 304.2.2.1, Laboratories and vocational shops International Building Code
1998 98-04 1106.4.7.7, Curb Ramp Orientation International Building Code
1998 98-03 1111 and 1103.1.2.1 International Building Code
1998 98-02 1103, Building Accessibility International Building Code
1998 98-01 1103.2.2, 1112, and 2902.3 International Building Code
NO YEAR SET 20-01 1307.3 IRC / 507.13 UPC International Residential Code, Uniform Plumbing Code
NO YEAR SET 20-01 1307.3 IRC / 507.13 UPC International Residential Code, Uniform Plumbing Code