WSR 20-02-057
PROPOSED RULES
BUILDING CODE COUNCIL
[Filed December 24, 2019, 8:57 a.m.]
Original Notice.
Preproposal statement of inquiry was filed as WSR 19-06-073.
Title of Rule and Other Identifying Information: Chapter 51-51 WAC, Amendments of the 2018 International Residential Code.
Hearing Location(s): On March 13, 2020, at 10:00 a.m., at the Department of Enterprise Services, Presentation Room (1213), 1500 Jefferson Street, Olympia, WA 98504.
Date of Intended Adoption: April 10, 2020.
Submit Written Comments to: Doug Orth, 1500 Jefferson Street S.E., Olympia, WA 98504, email SBCC@des.wa.gov, by March 6, 2020.
Assistance for Persons with Disabilities: Contact Carrie Toebbe, phone 360-407-9255, email carrie.toebbe@des.wa.gov, by March 6, 2020.
Purpose of the Proposal and Its Anticipated Effects, Including Any Changes in Existing Rules: The proposed rules address proposed state amendments to the 2018 edition of the International Residential Code (IRC), published by the International Code Council, as adopted by the Washington state building code council (SBCC). The rules will provide increased clarity and life safety measures for building construction in Washington state.
Summary of Proposed Changes:
2018 IRC
Amendments to WAC 51-51*
| WAC | Section | Changes in 2018 | Discussion |
1 | 51-51-020 | Definitions | Deleted definition for Air-Impermeable Insulation | |
2 | | | Defined Balanced Whole House Ventilation | New |
3 | | | Defined Battery System, Stationary Storage | Clerical - This was an approved definition but is included here because this definition had an effective date of July 1, 2020, and only one group of modifications to a WAC can have the same effective date. |
4 | | | Defined Building, Existing | Clerical - This was an approved definition but is included here because this definition had an effective date of July 1, 2020, and only one group of modifications to a WAC can have the same effective date. |
5 | | | Defined Building | Clerical - This was an approved definition but is included here because this definition had an effective date of July 1, 2020, and only one group of modifications to a WAC can have the same effective date. |
6 | | | Defined Distributed Whole House Ventilation | New |
7 | | | Modified the definition for Dwelling Unit | Clerical - This was an approved change but is included here because this change had an effective date of July 1, 2020, and only one group of modifications to a WAC can have the same effective date. |
8 | | | Defined Egress Roof Access Window | Clerical - This was an approved definition but is included here because this definition had an effective date of July 1, 2020, and only one group of modifications to a WAC can have the same effective date. |
9 | | | Defined Energy Storage Systems (ESS) | Clerical - This was an approved definition but is included here because this definition had an effective date of July 1, 2020, and only one group of modifications to a WAC can have the same effective date. |
10 | | | Defined Floor Area | Clerical - This was an approved definition but is included here because this definition had an effective date of July 1, 2020, and only one group of modifications to a WAC can have the same effective date. |
11 | | | Defined Landing Platform | Clerical - This was an approved definition but is included here because this definition had an effective date of July 1, 2020, and only one group of modifications to a WAC can have the same effective date. |
12 | | | Defined Local Exhaust | New |
13 | | | Defined Lot | Clerical - This was an approved definition but is included here because this definition had an effective date of July 1, 2020, and only one group of modifications to a WAC can have the same effective date. |
14 | | | Defined Lot Line | Clerical - This was an approved definition but is included here because this definition had an effective date of July 1, 2020, and only one group of modifications to a WAC can have the same effective date. |
15 | | | Defined Sleeping Loft | Clerical - This was an approved definition but is included here because this definition had an effective date of July 1, 2020, and only one group of modifications to a WAC can have the same effective date. |
16 | | | Defined Townhouse | Modification addressing exposure to yard or public way. |
17 | | | Defined Townhouse Unit | Clerical - This was an approved definition but is included here because this definition had an effective date of July 1, 2020, and only one group of modifications to a WAC can have the same effective date. |
18 | 51-51-1505 | 1505 Mechanical ventilation | Amendment renumbered from M1505.1 to M1503.2.1 | Clerical |
19 | | M1505.4.1 System design | Addresses ERV/HRVs. Requires ducted outdoor air | Modified model code language |
20 | | M1505.4.1.1 Whole house system component requirements | Addresses efficiency and sound rating requirements with exceptions | New text |
21 | | M1505.4.1.2 Exhaust fans | Addresses requirements including ducting directly to the outside | New text |
22 | | M1505.4.1.3 Supply fans. | Addresses requirements | New text |
23 | | M1505.4.1.4 Balanced whole house ventilation system | Addresses requirements | New text |
24 | | M1505.4.1.5 Furnace integrated supply | Prohibits space heating and/or cooling air handler fans for outdoor air supply distribution with an exception | New text |
25 | | M1505.4.1.6 Testing | Addresses requirements. Allows building official to require testing by a third party | New text |
26 | | M1505.4.1.7 Certificate | Requires a posted permanent compliance certificate | New text |
27 | | M1505.4.2 System controls | Addresses control requirements | Modified model code language |
28 | | M1505.4.3 Mechanical ventilation rate | Gives a minimum CFM per dwelling unit | Modified model code language |
29 | | Table M1505.4.3(1) Whole House mechanical ventilation airflow rate | Modifies ranges and airflow requirements | Modified model code table |
30 | | M1505.4.3.1 Ventilation quality adjustment | Addresses minimum whole house ventilation rate formula adjustments | New text |
31 | | Table M1505.4.3(2) System coefficient | Addresses balanced and not balanced | New table |
32 | | M1505.4.3.2 Intermittent off operation | Controls must provide for intermittent off operation | New text |
33 | | Table M1505.4.3(3) Intermittent off whole house mechanical ventilation rate factors | Modifies segments | Modified model code table |
34 | | M1505.4.4 Local exhaust rates | Clarifies reference | Clarification |
35 | | M1505.4.4.1 Local exhaust | Addresses bathrooms, toilet rooms and kitchens | Modified model code language |
36 | | M1505.4.4.2 Whole house exhaust controls | Addresses combining local exhaust with whole house ventilation system | New text |
37 | | Table M1505.4.4(1) Minimum local exhaust rates | Addresses bathrooms, toilet rooms and kitchens | Modified model code language |
38 | | M1505.4.4.3 Local exhaust fans | Addresses requirements | New text |
39 | | Table M1505.4.4(2) Prescriptive exhaust duct sizing | Addresses exhaust duct sizing | New table |
40 | 51-51-1507 | Section - Mechanical ventilation | Reserved | Section renumbered in model code Moved to 1505. |
41 | | M1507.1 General | Deleted | See Section 1505 |
42 | | M1507.2 Recirculation of air | Deleted | See Section 1505 |
43 | | M1507.3 Whole house mechanical ventilation system | Deleted | See Section 1505 |
44 | | M1507.4 Local exhaust | Moved to M1505.5 | Move |
45 | | Table M1507.4 Minimum required local exhaust rates | Moved to Table M1505.5 | Moved |
46 | | M1507.4.1 Local exhaust fans | Moved to M1505.5.1 | Moved |
47 | | M1507.4.2 Local exhaust controls | Moved to M1505.5.2 | Moved |
48 | | P2904.1.1 Required sprinkler locations | Addresses Uninhabitable attics | Changes "attic" to "uninhabitable attics." |
Reasons Supporting Proposal: To coordinate sections of the IRC with adopted amendments to the International Mechanical Code to avoid conflicting regulations as well as to make additional modifications to coordinate adopted amendments in the IRC.
Rule is not necessitated by federal law, federal or state court decision.
Name of Proponent: SBCC, governmental.
Name of Agency Personnel Responsible for Drafting and Implementation: Richard Brown, 1500 Jefferson Street S.E., Olympia, WA 98504, 360-407-9277; and Enforcement: Local jurisdictions having authority.
A school district fiscal impact statement is not required under RCW
28A.305.135.
A cost-benefit analysis is required under RCW
34.05.328. A preliminary cost-benefit analysis may be obtained by contacting Richard Brown, 1500 Jefferson Street S.E., Olympia, WA 98504, phone 360-407-9277, email
Richard.brown@des.wa.gov.
The proposed rule does impose more-than-minor costs on businesses. There are costs imposed by the proposed rules but the costs do not fall disproportionately on small businesses. These rules will not affect the distribution of impacted work, whether by small businesses or not, doing the work. The rules do not affect employment, reporting or record keeping.
Small Business Economic Impact Statement(RCW 19.85.040) Description: SBCC is filing a proposed rule to adopt the updated 2018 edition of the IRC (chapter 51-51 WAC). Since 1985, the SBCC has been responsible to update to new editions of the building code per RCW
19.27.074. The IRC is updated every three years by the International Code Council (ICC). The code development process conducted by the model code organization is open to all interest groups within the design and construction industry and from governmental organizations. See
www.iccsafe.org for more information about the model code development process.
The administrative compliance requirements are under the authority of the local government. RCW
19.27.050. Compliance activities including permit issuance, plan review and approval, and inspections occur at the local level. Requirements for construction document submittal and other reporting requirements are determined by the local jurisdiction and are consistent with previously established policies. The proposed amendments to chapter 51-51 WAC include specific technical requirements for building construction to be consistent with national standards.
Professional Services: Washington has had a statewide building code in effect since 1974. The local enforcement authority having jurisdiction administers the codes through the building and/or fire departments. Administrative procedures for state building code compliance are established and will not be changed by the adoption of the update to the current building codes. Small businesses will employ the same types of professional services for the design and construction of buildings and systems to comply with the state building code.
The proposed rule updates the state building code and does not require additional equipment, supplies, labor or other services. Services needed to comply with the building code are existing within the construction industry as required by the local authority having jurisdiction.
Costs of Compliance for Businesses: The cost of compliance incurred by Washington businesses includes training and educational materials. The IRC 2018 model code costs $99 + tax, shipping and handling. This publication is also available online at http://codes.iccsafe.org/I-Codes.html. The ICC chapters offer training for continuing education credits to architects, engineers and building inspectors for $285 (in 2016).
The building code technical advisory group (TAG) determined there is a cost for compliance on businesses for the following proposed state amendments.
1. All proposed changes to section M1505 will result in an estimated $1.20/square foot ($950/dwelling unit - multifamily only) with an anticipated full system payback in 11.2 years.
Loss of Sales or Revenue: Businesses with new products or updated test or design standards are recognized in the updated building code.
The update will result in some cost outlay for some small businesses for specific building projects, for a transition period. Other small businesses would see an increase in revenue. The amendments to all the building codes affect over twenty-five thousand (in 2012) small businesses in the state, where construction activity occurs. The primary intent of these amendments are to improve energy eficiency [efficiency] in buildings and provide consistency and fairness across the state, for a predictable business environment. The amendments should result in enhanced value in buildings.
Cost of Compliance for Small Businesses (Determine whether the proposed rule will have a disproportionate cost impact on small businesses, compare the cost of compliance for small business with the cost of compliance for the ten percent of businesses that are the largest businesses.): The majority of businesses affected by the updates to the building codes are small businesses; over ninety-five percent of those listed in the construction and related industries have under fifty employees. The costs per employee are comparable between the largest businesses and the majority of small businesses. The cost to comply with the updated codes is not a disproportionate impact on small business. Where the council found the cost of compliance for small businesses to be disproportionate, the proposed rule mitigates the cost. The proposed rules include a definition of small business and provide exceptions for compliance with the updated rule.
Reducing the Costs of the Rule on Small Businesses: The SBCC conducted a detailed review process, including participation at the national code development hearings, to document significant economic impacts of the proposed code amendments.
Small Businesses Involved in the Development of the Rule: For the IRC, the SBCC conducted ten open public meetings of the building code technical advisory group, available via telephone conference bridge and over the internet, and allowed comment on every item on every agenda. For the IRC TAG the SBCC appointed six representatives of all segments of the business and construction community to serve on the technical advisory groups.
List of Industries: Below is a list of industries required to comply with the building code:
North American Industry Classifica-tion System (NAICS) Code | NAICS Code Definition | Number of Establish-ments in Washington State | TOTAL Annual Payroll | TOTAL Annual Revenue | AVG Annual Payroll | AVG Annual Revenue | 1% of Avg Annual Payroll | 0.3% of Avg Annual Revenue |
236115 | New single-family housing construction (except for-sale builders) | 1261 | $186,272,000 | --- | $147,718 | --- | $1,477 | --- |
236116 | New multifamily housing construction (except for-sale builders) | 45 | $54,622,000 | --- | $1,213,822 | --- | $12,138 | --- |
236118 | Residential remodelers | 2777 | $318,180,000 | $1,536,217,000 | $114,577 | $553,193 | $1,146 | $1,660 |
236210 | Industrial building construction | 53(s) | $99,790,000 | --- | --- | --- | --- | --- |
236220 | Commercial and institutional building construction | 862 | $772,473,000 | $6,925,925,000 | $896,140 | $8,034,716 | $8,961 | $24,104 |
238110 | Poured concrete foundation and structure contractors | 511 | $144,643,000 | $479,256,000 | $283,059 | $937,879 | $2,831 | $2,814 |
238120 | Structural steel and precast concrete contractors | 68 | $93,454,000 | $336,100,000 | $1,374,324 | $4,942,647 | $13,743 | $14,828 |
238130 | Framing contractors | 417 | $79,196,000 | $279,226,000 | $189,918 | $669,607 | $1,899 | $2,009 |
238140 | Masonry contractors | 293 | $74,067,000 | $215,274,000 | $252,788 | $734,724 | $2,528 | $2,204 |
238150 | Glass and glazing contractors | 141 | $67,626,000 | $237,985,000 | $479,617 | $1,687,837 | $4,796 | $5,064 |
238160 | Roofing contractors | 537 | $179,942,000 | $660,911,000 | $335,088 | $1,230,747 | $3,351 | $3,692 |
238170 | Siding contractors | 327 | $58,557,000 | $286,471,000 | $179,073 | $876,058 | $1,791 | $2,628 |
238190 | Other foundation, structure, and building exterior contractors | 113 | $37,585,000 | $123,771,000 | $332,611 | $1,095,319 | $3,326 | $3,286 |
238210 | Electrical contractors and other wiring installation contractors | 1847 | $940,854,000 | $3,026,762,000 | $509,396 | $1,638,745 | $5,094 | $4,916 |
238220 | Plumbing, heating, and air-conditioning contractors | 1664 | $959,976,000 | $3,169,548,000 | $576,909 | $1,904,776 | $5,769 | $5,714 |
238290 | Other building equipment contractors | 81 | $117,696,000 | --- | $1,453,037 | --- | $14,530 | --- |
238310 | Drywall and insulation contractors | 653 | $282,929,000 | $723,945,000 | $433,276 | $1,108,644 | $4,333 | $3,325 |
238990 | All other specialty trade contractors | 547 | $182,710,000 | $573,308,000 | $334,022 | $1,048,095 | $3,340 | $3,144 |
321213 | Engineered wood member (except truss) manufacturing | 11 | $14,216,000 | $79,051,000 | $1,292,364 | $7,186,455 | $12,924 | $21,559 |
321214 | Truss manufacturing | 22 | --- | --- | --- | --- | --- | --- |
321219 | Reconstituted wood product manufacturing | 3 | --- | --- | --- | --- | --- | --- |
321911 | Wood window and door manufacturing | 39 | $37,814,000 | $145,137,000 | $969,590 | $3,721,462 | $9,696 | $11,164 |
321992 | Prefabricated wood building manufacturing | 18 | $6,891,000 | --- | $382,833 | --- | $382,833 | --- |
327310 | Cement manufacturing | 7 | --- | --- | --- | --- | --- | --- |
327320 | Ready-mix concrete manufacturing | 93 | $74,457,000 | --- | $800,613 | --- | $8,006 | --- |
327331 | Concrete block and brick manufacturing | 18 | $11,218,000 | --- | $623,222 | --- | $6,232 | --- |
332311 | Prefabricated metal building and component manufacturing | 9 | $3,564,000 | --- | $396,000 | --- | $3,960 | --- |
332312 | Fabricated structural metal manufacturing | 94 | $125,755,000 | --- | $1,337,819 | --- | $13,378 | --- |
332321 | Metal window and door manufacturing | 16 | $23,776,000 | --- | $1,486,000 | --- | $14,860 | --- |
332322 | Sheet metal work manufacturing | 122 | $122,956,000 | $573,443,000 | $1,007,836 | $4,700,352 | $10,078 | $14,101 |
335121 | Residential electric lighting fixture manufacturing | 9 | --- | --- | --- | --- | --- | --- |
335122 | Commercial, industrial, and institutional electric lighting fixture manufacturing | 8 | $2,625,000 | --- | $328,125 | --- | $3,281 | --- |
335129 | Other lighting equipment manufacturing | 4 | --- | --- | --- | --- | --- | --- |
423720 | Plumbing and heating equipment and supplies (hydronics) merchant wholesalers | 168 | $82,225,000 | $897,748,000 | $489,435 | $5,343,738 | $4,894 | $16,031 |
541310 | Architectural services | 635 | $326,798,000 | $921,033,000 | $514,643 | $1,450,446 | $5,146 | $4,351 |
541330 | Engineering services | 1599 | $1,758,825,000 | $3,946,553,000 | $1,099,953 | $2,468,138 | $11,000 | $7,404 |
541350 | Building inspection services | 154 | $9,724,000 | $28,297,000 | $63,143 | $183,747 | $631 | $551 |
561621 | Security systems services (except locksmiths) | 109 | $86,072,000 | $233,388,000 | $789,651 | $2,141,174 | $7,897 | $6,424 |
Note: | Data is blank in some fields to protect data source. |
Data Source: | Economic Census of the United States |
Estimate of the Number of Jobs That Will Be Created or Lost: The adoption of these amendments is not expected to significantly impact the number of jobs in the construction industry. These rules are likely to be job neutral overall, i.e., they will not result in any job gains or losses. The scheduled effective date of amendments is July 1, 2020. Building permits issued prior to that date will be vested under the 2015 building code. Permits issued for projects under the 2018 code edition will generally start with the 2021 construction season.
A copy of the statement may be obtained by contacting Richard Brown, 1500 Jefferson Street S.E., Olympia, WA 98504, phone 360-407-9277, email Richard.brown@des.wa.gov.
December 24, 2019
Doug Orth
Council Chair
AMENDATORY SECTION(Amending WSR 16-03-025, filed 1/11/16, effective 7/1/16)
WAC 51-51-0202Section R202—Definitions.
ADULT FAMILY HOME means a dwelling in which a person or persons provide personal care, special care, room and board to more than one but not more than six adults who are not related by blood or marriage to the person or persons providing the services.
((AIR-IMPERMEABLE INSULATION. An insulation having an air permeance equal to or less than 0.02 L/s-m2 at 75 Pa pressure differential tested in accordance with ASTM E2178 or ASTM E283.))
ATTIC, HABITABLE. A conditioned area complying with all of the following requirements:
1. The occupiable floor area is at least 70 square feet (6.5 m2), in accordance with Section R304.
2. The occupiable floor area has a ceiling height in accordance with Section R305.
3. The occupiable space is entirely enclosed by the roof assembly above, knee walls (if applicable) on the sides, and the floor-ceiling assembly below.
A habitable attic is not considered a story.
BALANCED WHOLE HOUSE VENTILATION. Balanced whole house ventilation is defined as any combination of concurrently operating residential unit mechanical exhaust and mechanical supply whereby the total mechanical exhaust airflow rate is within 10 percent or 5 cfm, whichever is greater, of the total mechanical supply airflow rate. Intermittent dryer exhaust, intermittent range hood exhaust, and intermittent toilet room exhaust airflow rates above the residential dwelling or sleeping unit minimum ventilation rate are exempt from the balanced airflow calculation.
BATTERY SYSTEM, STATIONARY STORAGE. This definition is not adopted.
BUILDING, EXISTING. A building or structure erected prior to the adoption of this code, or one that has passed a final inspection.
BUILDING. Any one- or two-family dwelling or townhouse, or portion thereof used or intended to be used for human habitation, for living, sleeping, cooking or eating purposes, or any combination thereof, or any accessory structure.
CHILD CARE, FAMILY HOME. A child care facility, licensed by Washington state, located in the dwelling of the person or persons under whose direct care and supervision the child is placed, for the care of twelve or fewer children, including children who reside at the home.
CHILD DAY CARE, shall, for the purposes of these regulations, mean the care of children during any period of a 24 hour day.
CONDITIONED SPACE. An area, room or space that is enclosed within the building thermal envelope and that is directly or indirectly heated or cooled. Spaces are indirectly heated or cooled where they communicate through openings with conditioned spaces, where they are separated from conditioned spaces by uninsulated walls, floors or ceilings, or where they contain uninsulated ducts, piping or other sources of heating or cooling.
DISTRIBUTED WHOLE HOUSE VENTILATION. A whole house ventilation system shall be considered distributed when it supplies outdoor air directly (not transfer air) to each dwelling or sleeping unit habitable space (living room, den, office, interior adjoining spaces, or bedroom), and exhausts air from all kitchens and bathrooms directly outside.
DWELLING UNIT. A single unit providing complete independent living facilities for one or more persons, including permanent provisions for living, sleeping, eating, cooking and sanitation. Dwelling units may also include the following uses:
1. Adult family homes, foster family care homes and family day care homes licensed by the Washington state department of social and health services.
2. Offices, mercantile, food preparation for off-site consumption, personal care salons or similar uses which are conducted primarily by the occupants of the dwelling unit and are secondary to the use of the unit for dwelling purposes, and which do not exceed 500 square feet (46.4 m2).
((3. One accessory dwelling unit, which need not be considered a separated dwelling unit, provided:
a. The accessory dwelling unit is constructed within an existing dwelling unit.
b. Either the accessory dwelling unit or primary dwelling unit is owner-occupied.
c. All required smoke alarms in the accessory dwelling unit and the primary dwelling unit are interconnected in such a manner that the actuation of one alarm will activate all alarms in both the primary dwelling unit and the accessory dwelling unit.))
EGRESS ROOF ACCESS WINDOW. A skylight or roof window designed and installed to satisfy the emergency escape and rescue opening requirements of Section R310.2.
ENERGY STORAGE SYSTEMS (ESS). One or more devices, assembled together, capable of storing energy in order to supply electrical energy at a future time.
FIRE SEPARATION DISTANCE. The distance measured from the foundation wall or face of the wall framing, whichever is closer, to one of the following:
1. To the closest interior lot line; or
2. To the centerline of a street, an alley or public way; or
3. To an imaginary line between two buildings on the lot.
The distance shall be measured at a right angle from the wall.
FLOOR AREA. The area within the inside perimeter of exterior walls of the building. The floor area of a building, or portion thereof, not provided with surrounding exterior walls shall be the usable area under the horizontal projection of the roof or floor above.
LANDING PLATFORM. A landing provided as the top step of a stairway accessing a sleeping loft.
LOCAL EXHAUST. An exhaust system that uses one or more fans to exhaust air from a specific room or rooms within a residential dwelling or sleeping unit.
LOT. A measured portion or parcel of land considered as a unit having fixed boundaries.
LOT LINE. The line which bounds a plot of ground described as a lot in the title to the property.
MEZZANINE, LOFT. An intermediate level or levels between the floor and ceiling of any story.
SALT WATER COASTAL AREA. Those areas designated as salt water coastal areas by the local jurisdiction.
SLEEPING LOFT. A sleeping space on a floor level located more than 30 inches (726 mm) above the main floor and open to the main floor one or more sides with a ceiling height of less than 6 feet 8 inches (2032 mm).
SMALL BUSINESS. Any business entity (including a sole proprietorship, corporation, partnership or other legal entity) which is owned and operated independently from all other businesses, which has the purpose of making a profit, and which has fifty or fewer employees.
TOWNHOUSE. A building that contains three or more attached townhouse units in which each unit extends from foundation to roof. Each single-family dwelling unit shall have a yard or public way on not less than two sides that extends at least 50 percent of the length of each of these two sides.
TOWNHOUSE UNIT. A single-family dwelling unit in a townhouse that extends from foundation to roof and that has a yard or public way on not less than two sides that extends at least 50 percent of the length of each of these two sides.
WHOLE HOUSE VENTILATION SYSTEM. A mechanical ventilation system, including fans, controls, and ducts, which replaces, by direct ((or indirect)) means, air from the habitable rooms with outdoor air.
AMENDATORY SECTION(Amending WSR 16-03-025, filed 1/11/16, effective 7/1/16)
WAC 51-51-1505Section M1505—((Overhead exhaust hoods))Mechanical ventilation.
((M1505.1 General. Domestic open-top broiler units shall have a metal exhaust hood, having a minimum thickness of 0.0157-inch (0.3950 mm) (No. 28 gage) with 1/4 inch (6.4 mm) clearance between the hood and the underside of combustible material or cabinets. A clearance of not less than 24 inches (610 mm) shall be maintained between the cooking surface and the combustible material or cabinet. The hood shall be not less than the width of the broiler unit, extend over the entire unit, and when located inside the building envelope, shall discharge to the outdoors and be equipped with a backdraft damper or other means to control infiltration/exfiltration when not in operation. Broiler units incorporating an integral exhaust system, and listed and labeled for use without an exhaust hood, or broiler units permanently installed outside the building envelope and having the cooking surface at least 5'0" below a 1-hour fire resistance rated ceiling, need not have an exhaust hood.))M1505.4 Whole-house mechanical ventilation system. Each dwelling unit shall be equipped with a ventilation system. The whole-house mechanical ventilation systems shall be designed in accordance with Sections M1505.4.1 through M1505.4.4.
M1505.4.1 System design. The whole house ventilation system shall consist of one or more supply fans, one or more exhaust fans, or an ERV/HRV with integral fans, associated ducts and controls. Whole-house mechanical ventilation system with supply and exhaust fans per Sections M1505.4.1.2, M1505.4.1.3, M1505.4.1.4, and M1505.4.1.5. Local exhaust fans are permitted to serve as part of the whole house ventilation system when provided with the proper controls per Section M1505.4.2. The systems shall be designed and installed to supply and exhaust the minimum outdoor airflow rates per Section M1505.4.3 as corrected by the balanced and/or distributed whole house ventilation system coefficients per Section M1504.5.3.1 where applicable. The whole house ventilation system shall operate continuously at the minimum ventilation rate determined per Section M1505.4.2 unless configured with intermittent off controls per Section M1505.4.3.2.
M1505.4.1.1 Whole house system component requirements. Whole house ventilation supply and exhaust fans specified in this section shall have a minimum efficacy as prescribed in the Washington State Energy Code. Design and installation of the system or equipment shall be carried out in accordance with manufacturers' installation instructions. Whole house ventilation fans shall be rated for sound at no less than the minimum airflow rate required by Section M1505.4.3.1. Ventilation fans shall be rated for sound at a maximum of 1.0 sone. This sound rating shall be at a minimum of 0.1 in. w.c. (25 Pa) static pressure in accordance with HVI procedures specified in Sections M1505.4.1.2 and M1505.4.1.3.
EXCEPTION: | HVAC air handlers, ERV/HRV units, and remote mounted fans need not meet the sound requirements. To be considered for this exception, a remote mounted fan must be mounted outside the habitable spaces, bathrooms, toilets, and hallways, and there must be at least 4 ft (1 m) of ductwork between the fan and the intake grille. |
The whole house supply fan shall provide ducted outdoor ventilation air to each habitable space within the residential unit.
EXCEPTION: | Interior joining spaces provided with a 30 cfm whole house transfer fan or a permanent opening with an area of not less than 8 percent of the floor area of the interior adjoining space but not less than 25 square feet do not require ducted outdoor ventilation air to be supplied directly to the space. Whole house transfer fans shall meet the sone rating of Section M1505.4.1.1 and shall have whole house ventilation controls that comply with Section M1505.4.2. |
M1505.4.1.2 Exhaust fans. Exhaust fans required shall be ducted directly to the outside. Exhaust air outlets shall be designed to limit the pressure difference to the outside to limiting the outlet free area maximum velocity to 500 ft per min and equipped with backdraft dampers or motorized dampers in accordance with Washington State Energy Code. Exhaust fans shall be tested and rated in accordance with the airflow and sound rating procedures of the Home Ventilating Institute (HVI 915, HVI Loudness Testing and Rating Procedure, HVI 916, HVI Airflow Test Procedure, and HVI 920, HVI Product Performance Certification Procedure). Exhaust fans required in this section may be used to provide local ventilation. Exhaust fans that are designed for intermittent exhaust airflow rates higher than the continuous exhaust airflow rates in Table 403.8.3 shall be provided with occupancy sensors or humidity sensors to automatically override the fan to the high speed airflow rate. The exhaust fans shall be tested and the testing results shall be submitted and posted in accordance with Section 403.8.6.7.
M1505.4.1.3 Supply fans. Supply fans used in meeting the requirements of this section shall supply outdoor air from intake openings in accordance with IMC Sections 401.4 and 401.5. Intake air openings shall be designed to limit the pressure difference to the outside to limiting the intlet free area maximum velocity to 500 ft per min and when designed for intermittent off operation shall be equipped with motorized dampers in accordance with Washington State Energy Code. Supply fans shall be tested and rated in accordance with the airflow and sound rating procedures of the Home Ventilating Institute (HVI 915, HVI Loudness Testing and Rating Procedure, HVI 916, HVI Airflow Test Procedure, and HVI 920, HVI Product Performance Certification Procedure). Where outdoor air is provided to each habitable dwelling unit or sleeping unit by supply fan systems the outdoor air shall be filtered. The filter shall be accessible for regular maintenance and replacement. The filter shall have a Minimum Efficiency Rating Value (MERV) of at least 8.
M1505.4.1.4 Balanced whole house ventilation system. A balanced whole house ventilation system shall include both supply and exhaust fans. The supply and exhaust fans shall have airflow that is within 10 percent of each other. The tested and balanced total mechanical exhaust airflow rate is within 10 percent or 5 cfm, whichever is greater, of the total mechanical supply airflow rate. The flow rate test results shall be submitted and posted in accordance with Section M1505.4.1.7. The exhaust fan shall meet the requirements of Section M1505.4.1.2. The supply fan shall meet the requirements of Section M1505.4.1.3. For dwelling units required by the Washington State Energy Code to have a balanced system, the system is required to have balanced whole house ventilation but is not required to have distributed whole house ventilation where the distributed system coefficient from Table 403.8.2 is utilized to correct the whole-house mechanical ventilation rate. Intermittent dryer exhaust, intermittent range hood exhaust, and intermittent toilet room exhaust airflow rates above the residential dwelling or sleeping unit minimum ventilation rate are exempt from the balanced airflow calculation.
M1505.4.1.5 Furnace integrated supply. Systems using space heating and/or cooling air handler fans for outdoor air supply distribution are not permitted.
EXCEPTION: | Air handler fans shall have multispeed or variable speed supply airflow control capability with a low speed operation not greater than 25 percent of the rated supply airflow capacity during ventilation only operation. Outdoor air intake openings must meet the provisions of Sections R303.5 and R303.6 and must include a motorized damper that is activated by the whole house ventilation system controller. The motorized damper must be controlled to maintain the outdoor airflow intake airflow within 10 percent of the whole house mechanical exhaust airflow rate. The flow rate for the outdoor air intake must be tested and verified at the minimum ventilation fan speed and the maximum heating or cooling fan speed. The results of the test shall be submitted and posted in accordance with Section M1505.4.1.7. |
M1505.4.1.6 Testing. Whole-house mechanical ventilation systems shall be tested, balanced and verified to provide a flow rate not less than the minimum required by Sections M1505.4.3 and M1505.4.4. Testing shall be performed according to the ventilation equipment manufacturer's instructions, or by using a flow hood, flow grid, or other airflow measuring device at the mechanical ventilation fan's inlet terminals, outlet terminals or grilles or in the connected ventilation ducts. Where required by the building official, testing shall be conducted by an approved third party. A written report of the results of the test shall be signed by the party conducting the test and provided to the building official and be posted in the dwelling unit per Section M1505.4.1.7.
M1505.4.1.7 Certificate. A permanent certificate shall be completed by the mechanical contractor, test and balance contractor or other approved party and posted on a wall in the space where the furnace is located, a utility room, or an approved location inside the building. When located on an electrical panel, the certificate shall not cover or obstruct the visibility of the circuit directory label, service disconnect label, or other required labels. The certificate shall list the flow rate determined from the delivered airflow of the whole-house mechanical ventilation system as installed and the type of mechanical whole house ventilation system used to comply with Section M1505.4.3.1.
M1505.4.2 System controls. The whole-house mechanical ventilation system shall be provided with controls that comply with the following:
1. The whole house ventilation system shall be controlled with manual switches, timers or other means that provide for automatic operation of the ventilation system that are readily accessible by the occupant;
2. Whole-house mechanical ventilation system shall be provided with controls that enable manual override off of the system by the occupant during periods of poor outdoor air quality. Controls shall include permanent text or a symbol indicating their function. Recommended control permanent labeling to include text similar to the following: "Leave on unless outdoor air quality is very poor." Manual controls shall be readily accessible by the occupant;
3. Whole house ventilation systems shall be configured to operate continuously except where intermittent off controls and sizing are provided per Section M1505.4.3.2.
M1505.4.3 Mechanical ventilation rate. The whole-house mechanical ventilation system shall provide outdoor air at a continuous rate as determined in accordance with Table M1505.4.3(1) or Equation 15-1.
Equation 15-1
Ventilation rate in cubic feet per minute = (0.01 × total square foot area of house) + [7.5 × (number of bedrooms + 1)] but not less than 30 cfm for each dwelling unit
Table M1505.4.3(1)
Whole-House Mechanical Ventilation Airflow Rate
| Number of Bedrooms |
Dwelling Unit Floor Area (square feet) | 0 - 1 | 2 | 3 | 4 | 5 or more |
| Airflow in cfm |
< 500 | 30 | 30 | 35 | 45 | 50 |
501 - 1,000 | 30 | 35 | 40 | 50 | 55 |
1,001 - 1,500 | 30 | 40 | 45 | 55 | 60 |
1,501 - 2,000 | 35 | 45 | 50 | 60 | 65 |
2,001 - 2,500 | 40 | 50 | 55 | 65 | 70 |
2,501 - 3,000 | 45 | 55 | 60 | 70 | 75 |
3,001 - 3,500 | 50 | 60 | 65 | 75 | 80 |
3,501 - 4,000 | 55 | 65 | 70 | 80 | 85 |
4,001 - 4,500 | 60 | 70 | 75 | 85 | 90 |
4,501 - 5,000 | 65 | 75 | 80 | 90 | 95 |
M1505.4.3.1 Ventilation quality adjustment. The minimum whole house ventilation rate from Section 1505.4.3 shall be adjusted by the system coefficient in Table M1505.4.3(2) based on the system type not meeting the definition of a balanced whole house ventilation system and/or not meeting the definition of a distributed whole house ventilation system.
Qv = Qr * Csystem
(Equation 15-2)
Where: | | |
Qv | = | Quality-adjusted ventilation airflow rate in cubic feet per minute (cfm). |
Qr | = | Ventilation airflow rate, cubic feet per minute (cfm) from 15-1 or Table M1505.4.3(1). |
Csystem | = | System coefficient from Table 1505.4.3(2). |
Table M1505.4.3(2)
System Coefficient (Csystem)
System Type | Distributed | Not Distributed |
Balanced | 1.0 | 1.25 |
Not balanced | 1.25 | 1.5 |
M1505.4.3.2 Intermittent off operation. Whole-house mechanical ventilation systems shall be provided with advanced controls that are configured to operate the system with intermittent off operation shall operate for a least two hours in each four-hour segment. The whole house ventilation airflow rate determined in accordance with Section M1505.4.3 as corrected by Section M1505.4.3.1 is multiplied by the factor determined in accordance with Table M1505.4.3(3).
Table M1505.4.3(3)
Intermittent Off Whole House-Mechanical Ventilation Rate Factorsa,b
Run-time % in Each 4-hour Segment | 50% | 66% | 75% | 100% |
Factora | 2 | 1.5 | 1.3 | 1.0 |
a. For ventilation system run-time values between those given, the factors are permitted to be determined by interpolation.
b. Extrapolation beyond the table is prohibited.
M1505.4.4 Local exhaust rates. Local exhaust systems shall be designed to have the capacity to exhaust the minimum airflow rate determined in accordance with Table M1505.4.4(1). If the local exhaust fan is included in the whole house ventilation system, in accordance with Section 1505.4.1, then the exhaust fan shall be controlled to operate as specified in Section M1505.4.2.
M1505.4.4.1 Local exhaust. Bathrooms, toilet rooms, and kitchens shall include a local exhaust system. Such local exhaust systems shall have the capacity to exhaust the minimum airflow rate in accordance with Table M1505.4.4(1). Fans required by this section shall be provided with controls that enable manual override or automatic occupancy sensor, humidity sensor or pollutant sensor controls. An "on/off" switch shall meet this requirement for manual controls. Manual fan controls shall be readily accessible in the room served by the fan.
Table M1505.4.4(1)
Minimum Local Exhaust Rates
Area to Be Exhausted | Exhaust Rates |
Intermittent | Continuous |
Kitchens | 100 cfm | 30 cfm |
Bathrooms - Toilet rooms | 50 cfm | 20 cfm |
M1505.4.4.2 Local exhaust fans. Exhaust fans shall meet the following criteria:
1. Exhaust fans shall be tested and rated in accordance with the airflow and sound rating procedures of the Home Ventilating Institute (HVI 915, HVI Loudness Testing and Rating Procedure, HVI 916, HVI Airflow Test Procedure, and HVI 920, HVI Product Performance Certification Procedure).
EXCEPTION: | Where a range hood or down draft exhaust fan is used for local exhaust for a kitchen, the device is not required to be rated per these standards. |
2. Fan airflow rating and duct system shall be designed and installed to deliver at least the exhaust airflow required by Table M1505.4.4(1). The airflows required refer to the delivered airflow of the system as installed and tested using a flow hood, flow grid, or other airflow measurement device. Local exhaust systems shall be tested, balanced, and verified to provide a flow rate not less than the minimum required by this section.
3. Design and installation of the system or equipment shall be carried out in accordance with manufacturers' installation instructions.
4. Fan airflow rating and duct system shall be designed and installed to deliver at least the exhaust airflow required by Table M1505.4.4(1).
EXCEPTIONS: | 1. An exhaust airflow rating at a pressure of 0.25 in. w.g. may be used, provided the duct sizing meets the prescriptive requirements of Table M1505.4.4(2). |
| 2. Where a range hood or down draft exhaust fan is used to satisfy the local ventilation requirements for kitchens, the range hood or down draft exhaust shall not be less than 100 cfm at 0.10 in. w.g. |
Table M1505.4.4(2)
Prescriptive Exhaust Duct Sizing
Fan Tested cfm at 0.25 inches w.g. | Minimum Flex Diameter | Maximum Length in Feet | Minimum Smooth Diameter | Maximum Length in Feet | Maximum Elbowsa |
50 | 4 inches | 25 | 4 inches | 70 | 3 |
50 | 5 inches | 90 | 5 inches | 100 | 3 |
50 | 6 inches | No Limit | 6 inches | No Limit | 3 |
80 | 4 inchesb | NA | 4 inches | 20 | 3 |
80 | 5 inches | 15 | 5 inches | 100 | 3 |
80 | 6 inches | 90 | 6 inches | No Limit | 3 |
100 | 5 inchesb | NA | 5 inches | 50 | 3 |
100 | 6 inches | 45 | 6 inches | No Limit | 3 |
125 | 6 inches | 15 | 6 inches | No Limit | 3 |
125 | 7 inches | 70 | 7 inches | No Limit | 3 |
a. For each additional elbow, subtract 10 feet from length.
b. Flex ducts of this diameter are not permitted with fans of this size.
Reviser's note: The brackets and enclosed material in the text of the above section occurred in the copy filed by the agency and appear in the Register pursuant to the requirements of RCW
34.08.040.
AMENDATORY SECTION(Amending WSR 16-03-025, filed 1/11/16, effective 7/1/16)
WAC 51-51-1507((Section M1507—Mechanical ventilation.))Reserved.
((M1507.1 General. Local exhaust and whole-house mechanical ventilation systems and equipment shall be designed in accordance with this section.
M1507.2 Recirculation of air. Exhaust air from bathrooms and toilet rooms shall not be recirculated within a residence or to another dwelling unit and shall be exhausted directly to the outdoors. Exhaust air from bathrooms and toilet rooms shall not discharge into an attic, crawl space or other areas of the building.
M1507.3 Whole-house mechanical ventilation system. Whole-house mechanical ventilation systems shall be designed in accordance with Sections M1507.3.1 through M1507.3.3.
M1507.3.1 System design. Each dwelling unit or guestroom shall be equipped with a ventilation system complying with Section M1507.3.4, M1507.3.5, M1507.3.6 or M1507.3.7. Compliance is also permitted to be demonstrated through compliance with the International Mechanical Code or ASHRAE Standard 62.2.
M1507.3.2 Control and operation.
1. Location of controls. Controls for all ventilation systems shall be readily accessible by the occupant.
2. Instructions. Operating instructions for whole-house ventilation systems shall be provided to the occupant by the installer of the system.
3. Local exhaust systems. Local exhaust systems shall be controlled by manual switches, dehumidistats, timers, or other approved means.
4. Continuous whole-house ventilation systems. Continuous whole-house ventilation systems shall operate continuously and be equipped with an override control. A "fan on" switch shall be permitted as an override control. Controls shall be capable of operating the ventilation system without energizing other energy-consuming appliances. A clearly visible label shall be affixed to the controls that reads "Whole House Ventilation (see operating instructions)."
5. Intermittent whole-house ventilation systems. Intermittent whole-house ventilation systems shall comply with the following:
5.1. They shall be capable of operating intermittently and continuously.
5.2. They shall have controls capable of operating the exhaust fans, forced-air system fans, or supply fans without energizing other energy-consuming appliances.
5.3. The ventilation rate shall be adjusted according to the exception in Section 403.8.5.1.
5.4. The system shall be designed so that it can operate automatically based on the type of control timer installed.
5.5. The intermittent mechanical ventilation system shall operate at least one hour out of every four.
5.6. The system shall have a manual control and automatic control, such as a 24-hour clock timer.
5.7. At the time of final inspection, the automatic control shall be set to operate the whole-house fan according to the schedule used to calculate the whole-house fan sizing.
5.8. A label shall be affixed to the control that reads "Whole House Ventilation (see operating instructions)."
M1507.3.2.1 Operating instructions. Installers shall provide the manufacturer's installation, operating instructions, and a whole-house ventilation system operation description.
M1507.3.3 Mechanical ventilation rate. The whole-house mechanical ventilation system shall provide outdoor air to each dwelling unit at a continuous rate of not less than that determined in accordance with Table M1507.3.3(1).
EXCEPTION: | The whole-house mechanical ventilation system is permitted to operate intermittently where the system has controls that enable operation for not less than 25 percent of each 4-hour segment and the ventilation rate prescribed in Table M1507.3.3(1) is multiplied by the factor determined in accordance with Table M1507.3.3(2). |
Table M1507.3.3(1)
Continuous Whole-House Mechanical Ventilation System Airflow Rate Requirements
| NUMBER OF BEDROOMS |
Dwelling Unit Floor Area (square feet) | 0 - 1 | 2 - 3 | 4 - 5 | 6 - 7 | ˃ 7 |
| Airflow in CFM |
< 1,500 | 30 | 45 | 60 | 75 | 90 |
1,501 - 3,000 | 45 | 60 | 75 | 90 | 105 |
3,001 - 4,500 | 60 | 75 | 90 | 105 | 120 |
4,501 - 6,000 | 75 | 90 | 105 | 120 | 135 |
6,001 - 7,500 | 90 | 105 | 120 | 135 | 150 |
˃ 7,501 | 105 | 120 | 135 | 150 | 165 |
For SI: 1 square foot = 0.0929 m2, 1 cubic foot per minute = 0.0004719 m3/S.
Table M1507.3.3(2)
Intermittent Whole-House Mechanical Ventilation Rate Factorsa, b
Run-Time Percentage in Each 4-Hour Segment | 25% | 33% | 50% | 66% | 75% | 100% |
Factora | 4 | 3 | 2 | 1.5 | 1.3 | 1.0 |
a | For ventilation system run time values between those given, the factors are permitted to be determined by interpolation. |
b | Extrapolation beyond the table is prohibited. |
M1507.3.4 Whole-house ventilation using exhaust fans. This section establishes minimum prescriptive requirements for whole-house ventilation systems using exhaust fans. A system which meets all the requirements of this section shall be deemed to satisfy the requirements for a whole-house ventilation system.
M1507.3.4.1 Whole-house ventilation fans. Exhaust fans providing whole-house ventilation shall have a flow rating at 0.25 inches water gauge as specified in Table M1507.3.3(1). Manufacturers' fan flow ratings shall be determined according to HVI 916 or AMCA 210.
M1507.3.4.2 Fan noise. Whole-house fans located 4 feet or less from the interior grille shall have a sone rating of 1.0 or less measured at 0.1 inches water gauge. Manufacturer's noise ratings shall be determined as per HVI 915 (March 2009). Remotely mounted fans shall be acoustically isolated from the structural elements of the building and from attached duct work using insulated flexible duct or other approved material.
M1507.3.4.3 Fan controls. The whole-house ventilation fan shall meet the requirements of Section M1507.3.2 and M1507.3.2.1.
M1507.3.4.4Ventilation openings. Each habitable space shall be provided with outdoor air inlets or operable windows with an openable area not less than 4 square inches of net free area of opening for each 10 cfm of outdoor air required by Table M1507.3.3(1). Where outdoor air supplies are separated from exhaust points by doors, provisions shall be made to ensure air flow by installation of distribution ducts, undercutting doors, installation of grilles, transoms, or similar means. Doors shall be undercut to a minimum of 1/2 inch above the surface of the finish floor covering.
Individual room outdoor air inlets shall:
1. Have controllable and secure openings;
2. Be sleeved or otherwise designed so as not to compromise the thermal properties of the wall or window in which they are placed;
3. Any inlet or combination of inlets which provide 10 cfm at 10 Pascals are deemed equivalent to 4 square inches net free area.
Ventilation opening shall be screened or otherwise protected from entry by leaves or other material. Openings shall be controllable, securable and shall be designed to not compromise the thermal properties of the building envelope. Ventilation openings shall be located so as not to take air from the following areas:
1. Closer than 10 feet from an appliance vent outlet, unless such vent outlet is 3 feet above the outdoor air inlet.
2. Where it will pick up objectionable odors, fumes or flammable vapors.
3. A hazardous or unsanitary location.
4. A room or space having any fuel-burning appliances therein.
5. Closer than 10 feet from a vent opening of a plumbing drainage system unless the vent opening is at least 3 feet above the air inlet.
6. Attic, crawl spaces, or garages.
7. Asphalt roofs unless it is shown that no other location is permissible. In such cases the inlet opening shall be located a minimum of 2 feet from the nearest surface of the asphalt roofing, measured from the intake opening.
M1507.3.5 Whole-house ventilation integrated with a forced-air system. This section establishes minimum prescriptive requirements for whole-house ventilation systems integrated with forced-air ventilation systems. A system which meets all the requirements of this section shall be deemed to satisfy the requirements for a whole-house ventilation system.
M1507.3.5.1 Integrated whole-house ventilation systems. Integrated whole-house ventilation systems shall provide outdoor air at the rate calculated using Section M1507.3.3. Integrated forced-air ventilation systems shall distribute outdoor air to each habitable space through the forced-air system ducts. Integrated forced-air ventilation systems shall have an outdoor air inlet duct connecting a terminal element on the outside of the building to the return air plenum of the forced-air system, at a point within 4 feet upstream of the air handler. The outdoor air inlet duct connection to the return air stream shall be located upstream of the forced-air system blower and shall not be connected directly into a furnace cabinet to prevent thermal shock to the heat exchanger. The system will be equipped with a motorized damper connected to the automatic ventilation control as specified in Section M1507.3.2. The required flow rate shall be verified by field testing with a flow hood or a flow measuring station.
M1507.3.5.2 Ventilation duct insulation. All supply ducts in the conditioned space shall be insulated to a minimum of R-4.
M1507.3.5.3 Outdoor air inlets. Inlets shall be screened or otherwise protected from entry by leaves or other material. Outdoor air inlets shall be located so as not to take air from the following areas:
1. Closer than 10 feet from an appliance vent outlet, unless such vent outlet is 3 feet above the outdoor air inlet.
2. Where it will pick up objectionable odors, fumes or flammable vapors.
3. A hazardous or unsanitary location.
4. A room or space having any fuel-burning appliances therein.
5. Closer than 10 feet from a vent opening of a plumbing drainage system unless the vent opening is at least 3 feet above the air inlet.
6. Attic, crawl spaces, or garages.
M1507.3.6 Whole-house ventilation using a supply fan. This section establishes minimum prescriptive requirements for whole-house ventilation systems using an inline supply fan. A system which meets all the requirements of this section shall be deemed to satisfy the requirements for a whole-house ventilation system.
M1507.3.6.1 Outdoor air. Supply fan ventilation systems shall distribute outdoor air to each habitable space through the forced-air system ducts or through dedicated ducts to each habitable space. Supply fans shall have the capacity to provide the amount of outdoor air specified in Table M1507.3.3(1) at 0.40 inches water gauge as per HVI 916. The outdoor air must be filtered before it is delivered to habitable spaces. The filter may be located at the intake device, in line with the fan, or, in the case of a connection to the return plenum of the air handler, using the furnace filter. An outdoor air inlet shall be connected to either the supply or return air stream.
M1507.3.6.2 Ducts. An outdoor air inlet duct connection to the supply air stream shall be located downstream of the forced-air system blower. An outdoor air inlet duct connection to the return air stream shall be located at least 4 feet upstream of the forced-air system blower and its filter. Neither type of duct shall be connected directly into a furnace cabinet to prevent thermal shock to the heat exchanger. The outdoor air inlet duct shall be prescriptively sized in accordance with Table M1507.3.6.2. The terminal element on the outside of the building shall be sized 2 inches in diameter larger than the outdoor air inlet duct.
Table M1507.3.6.2
Prescriptive Supply Fan Duct Sizing
Supply Fan Tested cfm at 0.40" wg |
Specified Volume from Table 1507.3.3(1) | Minimum Smooth Duct Diameter | Minimum Flexible Duct Diameter |
50 - 90 cfm | 4 inch | 5 inch |
90 - 150 cfm | 5 inch | 6 inch |
150 - 250 cfm | 6 inch | 7 inch |
250 - 400 cfm | 7 inch | 8 inch |
M1507.3.6.3 Dampers. The system shall be equipped with a back-draft damper and one of the following:
1. A calibrated manual volume damper installed and set to meet the measured flow rates specified in Table M1507.3.3(1) by field testing with a pressure gauge and/or following manufacturer's installation instructions; or
2. A manual volume damper installed and set to meet the measured flow rates specified in Table M1507.3.3(1) by field testing with a flow hood or a flow measuring station; or
3. An automatic flow-regulating device sized to the specified flow rates in Table M1507.3.3(1) which provides constant flow over a pressure range of 0.20 to 0.60 inches water gauge.
M1507.3.6.4 Ventilation duct insulation. All supply ducts in the conditioned space shall be insulated to a minimum of R-4.
M1507.3.6.5 Outdoor air inlets. Inlets shall be screened or otherwise protected from entry by leaves or other material. Outdoor air inlets shall be located so as not to take air from the following areas:
1. Closer than 10 feet from an appliance vent outlet, unless such vent outlet is 3 feet above the outdoor air inlet.
2. Where it will pick up objectionable odors, fumes or flammable vapors.
3. A hazardous or unsanitary location.
4. A room or space having any fuel-burning appliances therein.
5. Closer than 10 feet from a vent opening of a plumbing drainage system unless the vent opening is at least 3 feet above the air inlet.
6. Attic, crawl spaces, or garages.
M1507.3.7 Whole-house ventilation using a heat recovery ventilation system. This section establishes minimum prescriptive requirements for whole-house ventilation using a heat recovery ventilation system.
M1507.3.7.1 Heat recovery ventilation systems. All duct work in heat recovery systems shall be sized and installed per the manufacturer's instructions. System minimum flow rating shall be not less than that specified in Table M1507.3.3(1). Heat recovery ventilation systems shall have a filter on the upstream side of the heat exchanger in both the intake and exhaust airstreams with a minimum efficiency rating value (MERV) of 6.
M1507.3.7.2 Ventilation duct insulation. All supply ducts in the conditioned space installed upstream of the heat exchanger shall be insulated to a minimum of R-4.
M1507.3.7.3 Outdoor air inlets. Inlets shall be screened or otherwise protected from entry by leaves or other material. Outdoor air inlets shall be located so as not to take air from the following areas:
1. Closer than 10 feet from an appliance vent outlet, unless such vent outlet is 3 feet above the outdoor air inlet.
2. Where it will pick up objectionable odors, fumes or flammable vapors.
3. A hazardous or unsanitary location.
4. A room or space having any fuel-burning appliances therein.
5. Closer than 10 feet from a vent opening of a plumbing drainage system unless the vent opening is at least 3 feet above the air inlet.
6. Attic, crawl spaces, or garages.
M1507.4 Local exhaust. Local exhaust shall be provided in each kitchen, bathroom, water closet, laundry room, indoor swimming pool, spa, and other rooms where water vapor or cooking odor is produced. Local exhaust systems shall be designed to have the capacity to exhaust the minimum air flow rate determined in accordance with Table M1507.4.
Table M1507.4
Minimum Required Local Exhaust Rates
For One- and Two-Family Dwellings
Area to Be Exhausted | Exhaust Rates |
Kitchens | 100 cfm intermittent or 25 cfm continuous |
Bathrooms - Toilet rooms Laundry rooms, indoor swimming pools, and spas | Mechanical exhaust capacity of 50 cfm intermittent or 20 cfm continuous |
For SI: | 1 cubic foot per minute = 0.0004719 m3/s. |
M1507.4.1 Local exhaust fans. Exhaust fans providing local exhaust shall have a minimum fan flow rating not less than 50 cfm at 0.25 inches water gauge for bathrooms, laundries, or similar rooms and 100 cfm at 0.25 inches water gauge for kitchens. Manufacturers' fan flow ratings shall be determined as per HVI 916 (April 1995) or AMCA 210.
EXCEPTION: | Where a range hood or down draft exhaust fan is used to satisfy the local exhaust requirements for kitchens, the range hood or down draft exhaust shall not be less than 100 cfm at 0.10 inches water gauge. |
M1507.4.2 Local exhaust controls. Local exhaust systems shall be controlled by manual switches, dehumidistats, timers, or other approved means. Local exhaust system controls shall be readily accessible.))
NEW SECTION
WAC 51-51-2904Section 2904—Dwelling unit fire-sprinkler systems.
P2904.1.1 Required sprinkler locations. Sprinklers shall be installed to protect all areas of a dwelling unit.
EXCEPTIONS: | 1. Uninhabitable attics, crawl spaces and normally unoccupied concealed spaces that do not contain fuel-fired appliances do not require sprinklers. In uninhabitable attics, crawl spaces and normally unoccupied concealed spaces that contain fuel-fired equipment, a sprinkler shall be installed above the equipment; however, sprinklers shall not be required in the remainder of the space. |
| 2. Clothes closets, linen closets and pantries not exceeding 24 square feet (2.2 m2) in area, with the smallest dimension not greater than 3 feet (915 mm) and having wall and ceiling surfaces of gypsum board. |