Original Notice.

Preproposal statement of inquiry was filed as WSR 00-03-017.

Title of Rule: Amendment of chapter 51-13 WAC, Washington State Ventilation and Indoor Air Quality Code.

Purpose: To consider whether to amend the 1997 Edition of the Washington State Ventilation and Indoor Air Quality Code (chapter 51-13 WAC).

Statutory Authority for Adoption: RCW 19.27.190 and 19.27.020.

Statute Being Implemented: Chapters 19.27 and 34.05 RCW.

Summary: The proposed rules include adoption of amendments to the 1997 Washington State Ventilation and Indoor Air Quality Code, including editorial corrections, a rewrite of Chapter 3 -Ventilation Systems for clarity, amendments to specific ventilation requirements, allowance of alternate systems for nonresidential applications and amendments to the radon resistive construction requirements.

Reasons Supporting Proposal: RCW 19.27.190 and 19.27.020.

Name of Agency Personnel Responsible for Drafting and Implementation: Judith Darst, P.O. Box 48300, Olympia, WA 98504, (360) 586-2251; and Enforcement: Local jurisdictions.

Name of Proponent: Washington State Building Code Council, governmental.

Agency Comments or Recommendations, if any, as to Statutory Language, Implementation, Enforcement, and Fiscal Matters: The council is seeking comments on the issues proposed in the rules shown below.

Rule is not necessitated by federal law, federal or state court decision.

Explanation of Rule, its Purpose, and Anticipated Effects: The proposed rule amends chapter 51-13 WAC, Washington State Ventilation and Indoor Air Quality Code. The purpose is to amend the 1997 Washington State Ventilation and Indoor Air Quality Code, including editorial corrections, a rewrite of Chapter 3 -Ventilation Systems for clarity, amendments to specific ventilation requirements, allowance of alternate systems for nonresidential applications and amendments to the radon resistive construction requirements. The proposed amendments will provide greater clarity, consistency, and ease of use than the published version for application in Washington state.

     Regulatory Review: In compliance with Executive Order 97-02, regulatory improvement, the following criteria for regulatory review will be considered at the time of final adoption of the rule.

     1. Need. This rule is in conformance with RCW 19.27.190 Indoor air quality. The council regularly reviews existing state-wide building codes. The purpose and objective of this review, as given in RCW 19.27.020, is to promote the health, safety and welfare of the occupants or users of buildings; to require minimum construction standards for the state of Washington; to permit the use of modern technical methods; to eliminate restrictive, obsolete, conflicting, duplicating and unnecessary regulations; and to provide standards to make buildings accessible to and usable by persons with physical disabilities. The technical advisory groups appointed by the council have identified rules that are obsolete, duplicative or ambiguous, and have proposed amendments and revisions.

     2. Effectiveness and Efficiency. The mission of the council is to adopt building codes for uniform application throughout the state. In the course of the regular rule review, the council examined regulatory alternatives and new technologies. The council has identified where alternatives can be used effectively and efficiently. The council efficiently achieves uniform state building codes by serving as the central administrative agency for state-wide adoption of building codes.

     3. Clarity. The council revised their filing procedure for state amendments to the national uniform codes. To enhance clarity, only those subsections with a state amendment will be filed under the main section number. The balance of the main section will remain as written in the national uniform code, as adopted by reference, unless otherwise noted. This reformatting change reorganizes and shortens the WACs.

     4. Intent and Statutory Authority. The proposed rule is consistent with the legislative intent of the statute chapter 19.27 RCW. The statute gives the council sufficient authority to maintain the state building code, and to amend and adopt state-wide codes as deemed appropriate.

     5. Coordination. The council rule-making process has included participation by national, state, and local building, fire, mechanical and plumbing officials, as well as state agency representatives for the Departments of Social and Health Services, Health, Labor and Industries, and the State Fire Marshal. The council actively seeks participation from other state agencies to assure that duplication and inconsistency is eliminated.

     6. Cost. The council appointed technical advisory groups and an Economic and Regulatory Assessment Committee to examine the costs and benefits associated with the revisions to the building codes.

     7. Fairness. The state amendments to the Ventilation and Indoor Air Quality Code proposed by the council are intended to mitigate disproportionate impact on the regulated community. The council is made up of representatives from the regulated community, as well as public and regulatory officials. In addition, the council enlisted the assistance of technical advisory groups, made up of the individuals, organizations and businesses impacted by the building codes, to review code changes and proposals.

Proposal Changes the Following Existing Rules: 1. Sections 101.4, 302.3.2, 303.4.1.3, 303.4.2.2, 303.4.3.4, and 303.4.4.2 (two options): This proposed amendment requires an affixed label for the whole house ventilation control. The second option also provides a reference to operating instructions and inserts a new section 101.4 Operating Instructions that requires installers to provide information consistent with the present Uniform Mechanical Code requirements for installed mechanical equipment.

     2. Chapter 3 reformat: This proposed amendment reorganizes Chapter 3 to help clarify the parameters of the requirements by system type. The other listed changes to Sections 302 and 303 are duplicated in multiple sections as they apply to each different system type.

     3. Sections 302.2.1 and 303.3.1: This proposed amendment adds a room with an unvented decorative gas log or decorative gas fireplace to the list of rooms requiring source specific ventilation.

     4. Sections 302.3.3, 303.3.2, 303.4.1.1, 303.4.1.2, and 303.4.1.5: This proposed amendment is editorial (updating referenced Home Ventilating Institute (HVI) testing standards to more current versions).

     5. Section 303.4.1.5: This proposed amendment adds a new exception that does not require outdoor air inlets for exhaust only ventilation systems if the home has a ducted forced air heating system that communicates with all habitable rooms and the interior doors are undercut.

     6. Section 303.4.2.1: This proposed amendment clarifies that flow rates for all three integrated whole house ventilation system options (motorized damper, manual damper, or automatic flow regulated device) must be field measured. This amendment also clarifies compliance requires meeting the "minimum" flow rates as specified in Table 3-2.

     7. Section 304.2: This proposed amendment allows alternate nonresidential systems designed in accordance with ASHRAE Standard 62.1.1999.

     8. Section 503.2.3: This proposed amendment changes the aggregate requirement for radon resistive construction from a specialized "radon rock" to a more common "pea gravel."

     9. Section 503.2.4: This proposed amendment relocates the soil-gas retarder membrane, required in radon resistive construction, from "directly under the concrete slab" to "directly on top of the aggregate and under a two inch layer of sand gravel."

     10. Section 503.2.6 and new section 503.4 (two options): This proposed amendment clarifies requirements for the "T" within the aggregate area, required in radon resistive construction, by specifying that the five foot perforated drain pipe shall extend in each direction from the tee. This amendment also increases the minimum pipe diameter required for slabs over 750 square feet and requires approval for slabs over 3000 square feet. The second option removes the exception that defines a sub-slab depressurization system and relocates the information by adding a new section 503.4.

     11. Section 503.2.8: This code section requires a separate vent pipe for each isolated aggregate area in radon resistive construction. This proposal amends the exception which allows separate aggregate areas to be considered as a single area. The amendment increases the required area of connection from a "three inch diameter" to an "area of twelve square inches." The frequency of joining the area is also increased from every "30 feet" to every "10 linear feet or fraction thereof." The amendment further defines the connection by requiring that it "allow air flow" and that it "remain free from obstruction."

     12. Section 503.3: This proposed amendment is a new section requiring a radon vent for crawlspace ventilation in radon resistive construction. The size of the required vent pipe is dependent on the area of the crawlspace and is consistent with the vent pipe sizing requirements for slabs.

A small business economic impact statement has been prepared under chapter 19.85 RCW.

     Proposed amendments to the following sections have been identified by the Mechanical and Ventilation Codes TAG and the Economic and Regulatory Assessment Committee as having a cost impact on businesses required to comply with the rule. The costs would be minor by the definition of the Economic Committee, at less than 1/4 of 1% of total construction cost.

     WAC 51-13-302.3.2 Labels for whole house fans in residences. Requires a label reading "Whole House Ventilation" be affixed to the automatic control timer specified in this section. The rule would impose a minor cost impact on homebuilders and mechanical contractors.

     WAC 51-13-502 Crawlspace radon vent pipe. Adds a requirement in 6 counties for a 3 inch to 4 inch diameter radon vent pipe in all new homes with a crawlspace. The cost is estimated to be about $120 for 4 inch pipe, $87 for 3 inch pipe, in a typical two story residence.

     WAC 51-13-503.2.4 Soil Gas retarder membrane. Adds a requirement for 2 inches of fine sand or pea gravel between membrane material and slab. Cost of material is estimated to be $15 to $30.

     WAC 51-13-503.2.6 Radon Vent. Adds to the required length of subslab vent pipe, and increases diameter of pipe from 3 inches to 4 inches for slabs over 750 square feet. The added material cost would be between $25 to $30 dollars.

     WAC 51-13-503.2.8 Separate Aggregate Areas, Radon Resistive Construction Increases area opening, from 7 square inches to 48 square inches, to join separate aggregate areas. Additional cost would be minimal.

A copy of the statement may be obtained by writing to Tim Nogler, Managing Director, Washington State Building Code Council, P.O. Box 48300, Olympia, WA 98504-8300, phone (360) 586-0486, fax (360) 586-5880.

RCW 34.05.328 does not apply to this rule adoption. The State Building Code Council is not listed in this section as one of the agencies required to comply with this regulation.

Hearing Location: Spokane City Council Chambers, West 808 Spokane Falls Boulevard, Spokane, WA, on September 15, 2000, at 10:00 a.m.; and at the Radisson Hotel, 17101 International Boulevard, SeaTac, WA, on October 13, 2000, at 10:00 a.m.

Assistance for Persons with Disabilities: Contact Sue Mathers by September 1, 2000, TDD (360) 753-2200, or (360) 753-1184.

Submit Written Comments to: Judy Wilson, Chairman, State Building Code Council, P.O. Box 48300, Olympia, WA 98504-8300, fax (360) 586-5880, by October 13, 2000.

Date of Intended Adoption: November 17, 2000.

August 1, 2000

Judy Wilson

Council Chairman

OTS-4216.1

AMENDATORY SECTION(Amending WSR 93-02-056, filed 1/6/93, effective 7/1/93)

WAC 51-13-101
Scope and general requirements.

     101.1 Title: This Code shall be known as the Washington State Ventilation and Indoor Air Quality Code.      It is herein referred to as "this Code".

     101.2 Intent: The purpose of this Code is to provide minimum standards for the design and installation of mechanical ventilation systems, the selection of structural materials used within the conditioned space, and the construction of radon mitigation systems for new construction.

     It is intended that these provisions provide flexibility to permit the use of innovative approaches and techniques.      These provisions are structured to permit compliance with the intent of this Code by demonstration of performance through on site testing or through engineered design.      This Code is not intended to abridge any safety or health requirements required under any other applicable codes or ordinances.

     101.3 Scope: This Code sets forth minimum requirements for ventilation in all occupancies, including the design of new construction.

     101.3.1 Application to Existing Buildings

     101.3.1.1 Additions to Existing Buildings: Additions to existing buildings or structures may be made without making the entire building comply, provided that the new addition shall conform to the provisions of this Code.

     EXCEPTIONS

     1.      Additions with less than 500 square feet of conditioned floor area are exempt from the requirements in this code for Whole House Ventilation Systems, Section 302.2.2.

     2.      Additions or alterations to existing buildings which do not require the construction of foundations, crawlspaces, slabs, or basements shall not be required to meet the requirements for radon protection.

     101.3.1.2 Alterations and Repairs: All alterations and repairs may be made to existing or moved buildings built or permitted prior to the enforcement of this Code without making the entire building comply with the provisions of this Code, provided the alterations or repairs comply with this Code.

     EXCEPTION: Air handling/conditioning equipment, which is being replaced without alteration or repair of the associated air distribution system is exempt from the requirements of this Code.

     101.3.1.3 Historic Buildings: Historic buildings are exempt from this Code only to the extent necessary to preserve those features essential to their historical appearance or function.

Option 1: No change

Option 2: If Option 2 to Sections 302.3.2 and 303.4.1.3 is approved, add a NEW SECTION 101.4

     101.4 Operating Instructions: Installers shall provide the manufacturer's installation, operating instructions, and a whole house ventilation system operation description.

[Statutory Authority: RCW 19.27.190(2) and 1992 c 132.      93-02-056, § 51-13-101, filed 1/6/93, effective 7/1/93.      Statutory Authority: RCW 19.27.190.      91-01-102, § 51-13-101, filed 12/18/90, effective 7/1/91.]

     301.1 General: The criteria of this chapter establish the design conditions upon which the minimum ventilation systems are to be based for all occupancies. Group R occupancies four (4) stories and less as defined by the Washington State Building Code shall comply with either Section 302 or 303. Section 304 applies to all other occupancies.

     301.2 Testing: At the discretion of the building official, flow testing may be required to verify that the mechanical system(s) satisfies the requirements of this section. Flow testing may be performed using flow hoods measuring at the intake or exhaust points of the system, in-line pitot tube, or pitot-traverse type measurement systems in the duct, short term tracer gas measurements, or other means approved by the building official.

[Statutory Authority: RCW 19.27.190.      91-01-102, § 51-13-301, filed 12/18/90, effective 7/1/91.]

     302.1 ((General: This section shall apply to all Group R occupancies four (4) stories and less as defined by the Washington State Building Code.      Residential structures greater than four (4) stories in height shall comply with Section 304, for outdoor air supply requirements.      For source specific ventilation requirements, see Section 302.2.1.      Compliance with this section shall be demonstrated through engineering calculations or performance testing.      Documentation of calculations shall be submitted to the building official where required.      Performance testing shall be conducted in accordance with recognized test methods.

     302.1.2 Testing: At the discretion of the building official, flow testing may be required to verify that the mechanical system(s) satisfies the requirements of this section.      Flow testing may be performed using flow hoods measuring at the intake or exhaust points of the system, in-line pitot tube, or pitot-traverse type measurement systems in the duct, short term tracer gas measurements, or other means approved by the building official.)) Applicability: Group R occupancies four (4) stories and less as defined by the Washington State Building Code shall comply with either this section or Section 303.

     302.1.1 Compliance by Calculations or Testing: Compliance with this section shall be demonstrated through engineering calculation or performance testing. Documentation of calculations or performance test results shall be submitted to the building official. Performance testing shall be conducted in accordance with recognized test methods.

     ((302.2)) Minimum Ventilation Performance: Each dwelling unit or guest room shall be equipped with source specific and whole house ventilation systems designed and installed to satisfy the ventilation requirements of this ((chapter)) section.

     ((EXCEPTION:)) All public corridors shall meet the ventilation requirements in section 1203.3 of the Uniform Building Code.

     302.2 Source Specific Ventilation Requirements.

     302.2.1 Source Specific Ventilation: Source specific exhaust ventilation ((shall be)) is required in each kitchen, bathroom, water closet, laundry room, indoor swimming pool, spa, room with an unvented decorative gas log or decorative gas fireplace, and other rooms where excess water vapor or cooking odor is produced.

     The minimum source specific ventilation effective exhaust capacity shall be not less than levels specified in Table 3-1.

     302.2.2 Source Specific Ventilation Controls: Source specific ventilation systems shall be controlled by manual switches, dehumidistats, timers, or other approved means. Source specific ventilation system controls shall be readily accessible.

     302.2.3 Source Specific Ventilation Ducts: Source specific ventilation ducts shall terminate outside the building. Exhaust ducts in systems which are designed to operate intermittently shall be equipped with back-draft dampers. All exhaust ducts in unconditioned spaces shall be insulated to a minimum of R-4. Terminal elements shall have at least the equivalent net free area of the duct work. Terminal elements for exhaust fan duct systems shall be screened or otherwise protected from entry by leaves or other material.

     302.3 Requirements for Whole House Ventilation Systems.

     ((302.2.2)) 302.3.1 Whole House Ventilation Systems: Each dwelling unit shall be equipped with a whole house ventilation system which shall be capable of providing ((at least 0.35 air changes per hour, but not less than fifteen cubic feet per minute per bedroom plus an additional fifteen cubic feet per minute.      Whole house ventilation systems shall be designed to limit ventilation to a level no greater than 0.5 air changes per hour)) the volume of outdoor air specified in Table 3-2 under normal ((operation)) operating conditions.      ((Whole house ventilation systems shall supply outdoor air to all habitable rooms through individual outdoor air inlets, forced-air heating system, ducting or equivalent means.      Doors and operable lites in windows are deemed not to meet the outdoor air supply intake requirements.))

EXCEPTION:

((For dwelling units of no more than 1,400 square feet, the maximum ventilation rate shall be 0.65 air changes per hour.)) Maximum flow rates listed in Table 3-2 do not apply to heat recovery ventilation systems.

((EXCEPTION:

Continuously operated whole house ventilation systems switch shall not be readily accessible by the occupant.

     302.3.1 Source Specific Ventilation Systems: Source specific ventilation systems shall be controlled by manual switches, dehumidistats, timers, or other approved means.

     302.3.2 Intermittently Operated Whole House Ventilation Systems: The)) Intermittently operated whole house ventilation systems shall be constructed to have the capability for continuous operation, and shall have a manual control and an automatic control, such as a clock timer.      At the time of final inspection, the automatic control timer shall be set to operate the whole house fan for ((a minimum of)) at least eight hours a day. A label shall be affixed to the control that reads "Whole House Ventilation."

     ((302.4)) 302.3.3 Fan Noise: Whole house fans located four feet or less from the interior grille shall have a sone rating of 1.5 or less measured at 0.1 inches water gauge.      Manufacturer's noise ratings shall be determined as per HVI 915 (October 1995). 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.

EXCEPTION:

Whole house ventilation systems which are integrated with forced-air heating systems or heat-recovery ventilation systems are exempt from the sone rating requirements of this section.

     ((302.5)) 302.3.4 Whole House Ventilation Ducts: All ducts shall terminate outside the building.      Exhaust ducts in systems which are designed to operate intermittently shall be equipped with back-draft dampers. All exhaust ducts in unconditioned spaces shall be insulated to a minimum of R-4.      All supply ducts in the conditioned space shall be insulated to a minimum of R-4.

     302.3.5 Outdoor Air.

     ((302.6)) 302.3.5.1 Outdoor Air Supply: A mechanical system shall supply outdoor air as required in Section ((302.2.2)) 302.3.1.      The mechanical system may consist of exhaust fans, supply fans, or both.

     ((302.6.1)) 302.3.5.2 Outdoor Air Inlets: Inlets shall be screened or otherwise protected from entry by ((insects,)) leaves((,)) or other material.      Outdoor air inlets shall be located so as not to take air from the following areas:

a) Closer than ten feet from an appliance vent outlet, unless such vent outlet is three feet above the outdoor air inlet.

b) Where it will pick up objectionable odors, fumes, or flammable vapors.

c) A hazardous or unsanitary location.

d) A room or space having any fuel-burning appliances therein.

e) Closer than ten feet from a vent opening of a plumbing drainage system unless the vent opening is at least three feet above the air inlet.

f) Attic, crawl spaces, garages.

     302.3.5.3 Outdoor Air Distribution: Outdoor air shall be distributed to each habitable room by means such as individual inlets, separate duct systems, or a forced-air system. 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 where permitted by the Uniform Building Code. Doors shall be undercut to a minimum of one-half inch above the surface of the finish floor covering.

     302.3.5.4 Doors and operable lites in windows are deemed not to meet the outdoor air supply intake requirements.

     ((302.6.2)) 302.3.5.5 Individual Room Outdoor Air Inlets: Where provided, individual room outdoor air inlets shall:

     a) have controllable and secure openings;

     b) be sleeved or otherwise designed so as not to compromise the thermal properties of the wall or window in which they are placed((;

     c) provide not less than four square inches of net free area of opening for each habitable space.      Any inlet or combination of inlets which provide 10 cfm at 10 Pascals as determined by the Home Ventilating Institute Air Flow Test Standard are deemed equivalent to four square inches net free area)).

     ((302.6.3)) 302.3.5.6 Ventilation Integrated with Forced-Air Systems: Where outdoor air is provided by a forced-air system, the outdoor air 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.

     ((302.6.4 Distribution: Outdoor air shall be distributed to each habitable room by individual inlets, separate duct systems, or a forced-air system.      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 where permitted by the Uniform Building Code.      Doors shall be undercut to a minimum of one-half inch above the surface of the finish floor covering.))

[Statutory Authority: RCW 19.27.190.      95-01-128, § 51-13-302, filed 12/21/94, effective 6/30/95.      Statutory Authority: RCW 19.27.190(2) and 1992 c 132.      93-02-056, § 51-13-302, filed 1/6/93, effective 7/1/93.      Statutory Authority: RCW 19.27.190.      91-01-102, § 51-13-302, filed 12/18/90, effective 7/1/91.]

     302.1 ((General: This section shall apply to all Group R occupancies four (4) stories and less as defined by the Washington State Building Code.      Residential structures greater than four (4) stories in height shall comply with Section 304, for outdoor air supply requirements.      For source specific ventilation requirements, see Section 302.2.1.      Compliance with this section shall be demonstrated through engineering calculations or performance testing.      Documentation of calculations shall be submitted to the building official where required.      Performance testing shall be conducted in accordance with recognized test methods.

     302.1.2 Testing: At the discretion of the building official, flow testing may be required to verify that the mechanical system(s) satisfies the requirements of this section.      Flow testing may be performed using flow hoods measuring at the intake or exhaust points of the system, in-line pitot tube, or pitot-traverse type measurement systems in the duct, short term tracer gas measurements, or other means approved by the building official.)) Applicability: Group R occupancies four (4) stories and less as defined by the Washington State Building Code shall comply with either this section or Section 303.

     302.1.1 Compliance by Calculations or Testing: Compliance with this section shall be demonstrated through engineering calculation or performance testing. Documentation of calculations or performance test results shall be submitted to the building official. Performance testing shall be conducted in accordance with recognized test methods.

     ((302.2)) Minimum Ventilation Performance: Each dwelling unit or guest room shall be equipped with source specific and whole house ventilation systems designed and installed to satisfy the ventilation requirements of this ((chapter)) section.

     ((EXCEPTION:)) All public corridors shall meet the ventilation requirements in section 1203.3 of the Uniform Building Code.

     302.2 Source Specific Ventilation Requirements.

     302.2.1 Source Specific Ventilation: Source specific exhaust ventilation ((shall be)) is required in each kitchen, bathroom, water closet, laundry room, indoor swimming pool, spa, room with an unvented decorative gas log or decorative gas fireplace, and other rooms where excess water vapor or cooking odor is produced.

     The minimum source specific ventilation effective exhaust capacity shall be not less than levels specified in Table 3-1.

     302.2.2 Source Specific Ventilation Controls: Source specific ventilation systems shall be controlled by manual switches, dehumidistats, timers, or other approved means. Source specific ventilation system controls shall be readily accessible.

     302.2.3 Source Specific Ventilation Ducts: Source specific ventilation ducts shall terminate outside the building. Exhaust ducts in systems which are designed to operate intermittently shall be equipped with back-draft dampers. All exhaust ducts in unconditioned spaces shall be insulated to a minimum of R-4. Terminal elements shall have at least the equivalent net free area of the duct work. Terminal elements for exhaust fan duct systems shall be screened or otherwise protected from entry by leaves or other material.

     302.3 Requirements for Whole House Ventilation Systems.

     ((302.2.2)) 302.3.1 Whole House Ventilation Systems: Each dwelling unit shall be equipped with a whole house ventilation system which shall be capable of providing ((at least 0.35 air changes per hour, but not less than fifteen cubic feet per minute per bedroom plus an additional fifteen cubic feet per minute.      Whole house ventilation systems shall be designed to limit ventilation to a level no greater than 0.5 air changes per hour)) the volume of outdoor air specified in Table 3-2 under normal ((operation)) operating conditions.      ((Whole house ventilation systems shall supply outdoor air to all habitable rooms through individual outdoor air inlets, forced-air heating system, ducting or equivalent means.      Doors and operable lites in windows are deemed not to meet the outdoor air supply intake requirements.))

EXCEPTION:

((For dwelling units of no more than 1,400 square feet, the maximum ventilation rate shall be 0.65 air changes per hour.)) Maximum flow rates listed in Table 3-2 do not apply to heat recovery ventilation systems.

((EXCEPTION:

Continuously operated whole house ventilation systems switch shall not be readily accessible by the occupant.

     302.3.1 Source Specific Ventilation Systems: Source specific ventilation systems shall be controlled by manual switches, dehumidistats, timers, or other approved means.

     302.3.2 Intermittently Operated Whole House Ventilation Systems: The)) Intermittently operated whole house ventilation systems shall be constructed to have the capability for continuous operation, and shall have a manual control and an automatic control, such as a clock timer.      At the time of final inspection, the automatic control timer shall be set to operate the whole house fan for ((a minimum of)) at least eight hours a day. A label shall be affixed to the control that reads "Whole House Ventilation (see operating instructions)."

     ((302.4)) 302.3.3 Fan Noise: Whole house fans located four feet or less from the interior grille shall have a sone rating of 1.5 or less measured at 0.1 inches water gauge.      Manufacturer's noise ratings shall be determined as per HVI 915 (October 1995). 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.

EXCEPTION:

Whole house ventilation systems which are integrated with forced-air heating systems or heat-recovery ventilation systems are exempt from the sone rating requirements of this section.

     ((302.5)) 302.3.4 Whole House Ventilation Ducts: All ducts shall terminate outside the building.      Exhaust ducts in systems which are designed to operate intermittently shall be equipped with back-draft dampers. All exhaust ducts in unconditioned spaces shall be insulated to a minimum of R-4.      All supply ducts in the conditioned space shall be insulated to a minimum of R-4.

     302.3.5 Outdoor Air.

     ((302.6)) 302.3.5.1 Outdoor Air Supply: A mechanical system shall supply outdoor air as required in Section ((302.2.2)) 302.3.1.      The mechanical system may consist of exhaust fans, supply fans, or both.

     ((302.6.1)) 302.3.5.2 Outdoor Air Inlets: Inlets shall be screened or otherwise protected from entry by ((insects,)) leaves((,)) or other material.      Outdoor air inlets shall be located so as not to take air from the following areas:

a) Closer than ten feet from an appliance vent outlet, unless such vent outlet is three feet above the outdoor air inlet.

b) Where it will pick up objectionable odors, fumes, or flammable vapors.

c) A hazardous or unsanitary location.

d) A room or space having any fuel-burning appliances therein.

e) Closer than ten feet from a vent opening of a plumbing drainage system unless the vent opening is at least three feet above the air inlet.

f) Attic, crawl spaces, garages.

     302.3.5.3 Outdoor Air Distribution: Outdoor air shall be distributed to each habitable room by means such as individual inlets, separate duct systems, or a forced-air system. 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 where permitted by the Uniform Building Code. Doors shall be undercut to a minimum of one-half inch above the surface of the finish floor covering.

     302.3.5.4 Doors and operable lites in windows are deemed not to meet the outdoor air supply intake requirements.

     ((302.6.2)) 302.3.5.5 Individual Room Outdoor Air Inlets: Where provided, individual room outdoor air inlets shall:

     a) have controllable and secure openings;

     b) be sleeved or otherwise designed so as not to compromise the thermal properties of the wall or window in which they are placed((;

     c) provide not less than four square inches of net free area of opening for each habitable space.      Any inlet or combination of inlets which provide 10 cfm at 10 Pascals as determined by the Home Ventilating Institute Air Flow Test Standard are deemed equivalent to four square inches net free area)).

     ((302.6.3)) 302.3.5.6 Ventilation Integrated with Forced-Air Systems: Where outdoor air is provided by a forced-air system, the outdoor air 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.

     ((302.6.4 Distribution: Outdoor air shall be distributed to each habitable room by individual inlets, separate duct systems, or a forced-air system.      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 where permitted by the Uniform Building Code.      Doors shall be undercut to a minimum of one-half inch above the surface of the finish floor covering.))

[Statutory Authority: RCW 19.27.190.      95-01-128, § 51-13-302, filed 12/21/94, effective 6/30/95.      Statutory Authority: RCW 19.27.190(2) and 1992 c 132.      93-02-056, § 51-13-302, filed 1/6/93, effective 7/1/93.      Statutory Authority: RCW 19.27.190.      91-01-102, § 51-13-302, filed 12/18/90, effective 7/1/91.]

     303.1 ((General:)) Applicability: Group R Occupancies 4 stories or less shall comply with this section or Section 302. This section establishes minimum prescriptive design requirements for intermittently operated systems.      Continuously operated systems shall comply with section 302.      ((System characteristics not addressed in the following sections shall comply with section 302.))      A system which meets the requirements of this section shall be deemed to satisfy the requirements of this chapter.

     ((303.1.1 Source Specific: Exhaust fans providing source specific ventilation shall have a minimum fan flow rating not less than fifty cfm at 0.25 inches water gauge for bathrooms, laundries, or similar rooms and one hundred cfm at 0.25 inches water gauge for kitchens.      Manufacturers' fan flow ratings shall be determined as per HVI 916 (July 1989) or AMCA 210.

EXCEPTION:

Where a range hood or down draft exhaust fan is used to satisfy the source specific ventilation requirements for kitchens, the range hood or down draft exhaust shall not be less than 100 CFM at 0.10 inches water gauge.

     303.1.2 Whole House: Whole house ventilation systems may consist of whole house exhaust, integration with forced-air systems or dedicated heat recovery ventilation systems.      Whole house ventilation systems shall provide ventilation capacity as specified in Table 3-2 and meet the following requirements:

     a) Exhaust fans providing whole house ventilation shall have a flow rating at 0.25 inches water gauge as specified in Table 3-2.      Manufacturer's fan flow ratings shall be determined as per HVI 916 (July 1989) or AMCA 210.      Table 3-2 shall not be used for dwelling units with more than five bedrooms.

     b) 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, and be equipped with one of the following:

     1) A motorized damper connected to the automatic ventilation control as specified in Section 302.3.2; or

     2) A damper installed and set to meet measured flow rates as specified in Table 3-2, by either field testing or following manufacturer's installation instructions based on site conditions; or

     3) An automatic flow regulated device with field measured or field calculated minimum negative pressure differential of 0.07 inches water gauge at the point where the outside air duct is connected to the return air plenum.

     c) Heat recovery ventilation systems: All duct work in heat recovery ventilation systems shall be not less than six inch diameter.      Balancing dampers shall be installed on the inlet and exhaust side.      Flow measurement grids shall be installed on the supply and return.      System minimum flow rating shall be not less than that specified in Table 3-2.      Maximum flow rates in Table 3-2 do not apply to heat recovery ventilation systems.))

     303.2 ((Source specific and whole house ventilation ducts: Exhaust ducts shall meet all requirements of section 302.5.      Duct diameter, length, and number of elbows for exhaust fans shall be as specified in Table 3-3.      Terminal elements for exhaust fan duct systems shall have at least the equivalent net free area of the duct work.      Duct diameter, length, and number of elbows for integrated forced air systems shall be as specified in Table 3-5.      Terminal elements for integrated systems shall be the same size as the connecting ductwork or 8 inches in diameter whichever is greater.)) Minimum Ventilation Performance: Each dwelling unit or guest room shall be equipped with source specific and whole house ventilation systems designed and installed to satisfy the ventilation requirements of this section. All public corridors shall meet the ventilation requirements in Section 1203.3 of the Uniform Building Code.

     303.3 Source Specific Exhaust Ventilation Requirements.

     303.3.1 Source Specific Ventilation: Source specific exhaust ventilation is required in each kitchen, bathroom, water closet, laundry room, indoor swimming pool, spa, room with an unvented decorative gas log or decorative gas fireplace and other rooms where excess water vapor or cooking odor is produced. The minimum source specific ventilation effective exhaust capacity shall be not less than levels specified in Table 3-1.

     303.3.2 Source Specific Exhaust Fans: Exhaust fans providing source specific ventilation 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 source specific ventilation requirements for kitchens, the range hood or down draft exhaust shall not be less than 100 cfm at 0.10 inches water gauge.

     303.3.3 Source Specific Ventilation Controls: Source specific ventilation systems shall be controlled by manual switches, dehumidistats, timers, or other approved means. Source specific ventilation system controls shall be readily accessible.

     303.3.4 Source Specific Ventilation Ducts: Source specific ventilation ducts shall terminate outside the building. Exhaust ducts shall be equipped with back-draft dampers. All exhaust ducts in unconditioned spaces shall be insulated to a minimum of R-4. Terminal elements shall have at least the equivalent net free area of the duct work. Terminal elements for exhaust fan duct systems shall be screened or otherwise protected from entry by leaves or other material.

     303.4 Prescriptive Whole House Ventilation Systems: Whole house ventilation shall be provided by a system that meets the requirements of either Section 303.3.1, 303.3.2, 303.3.3, or 303.3.4. A system which meets all of the requirements of one of these sections shall be deemed to satisfy the requirements for a whole house ventilation system.

     303.4.1 Intermittent Whole House Ventilation Using Exhaust Fans: This section establishes minimum prescriptive requirements for intermittent 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.

     303.4.1.1 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 3-2. Manufacturers' fan flow ratings shall be determined according to HVI 916 (April 1995) or AMCA 210.

     303.4.1.2 Fan Noise: Whole house fans located four feet or less from the interior grille shall have a sone rating of 1.5 or less measured at 0.1 inches water gauge. Manufacturer's noise ratings shall be determined as per HVI 915 (October 1995). 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.

     f. Attic, crawl spaces, or garages.

EXCEPTION:

Exhaust only ventilation systems do not require outdoor air inlets if the home has a ducted forced air heating system that communicates with all habitable rooms and the interior doors are undercut to a minimum of one-half inch above the surface of the finish floor covering.

     303.4.2 Prescriptive Requirements for Intermittent Whole House Ventilation Integrated with a Forced-Air System: This section establishes minimum prescriptive requirements for intermittent 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.

     303.4.2.1 Integrated Whole House Ventilation Systems: Integrated Whole House Ventilation Systems shall provide outdoor air at the rates specified in Table 3-2. Integrated Forced-Air Ventilation Systems shall distribute outdoor air to each habitable room 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 four (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 outdoor air inlet duct shall be prescriptively sized in accordance with Table 3-5. The system will be equipped with one of the following:

     1. A motorized damper connected to the automatic ventilation control as specified in Section 303.3.2.2, field measured and set to meet minimum flow rates as specified in Table 3-2; or

     2. A damper installed, field measured and set to meet minimum flow rates as specified in Table 3-2; or

     3. An automatic flow regulated device with field measured minimum negative pressure of 0.07 inches water gauge at the point where the outside air duct is connected to the return air plenum.

     f. Attic, crawl spaces, or garages.

[Statutory Authority: RCW 19.27.190(2) and 1992 c 132.      93-02-056, § 51-13-303, filed 1/6/93, effective 7/1/93.      Statutory Authority: RCW 19.27.190.      91-01-102, § 51-13-303, filed 12/18/90, effective 7/1/91.]

     304.1 Ventilation: The minimum requirements for operable area to provide natural ventilation are specified in the Uniform Building Code (UBC) as adopted by the state of Washington.

     Where a mechanical ventilation system is installed, the mechanical ventilation system shall be capable of supplying ventilation air to each zone with the minimum outdoor air quantities specified in Table 3-4.

EXCEPTION:

Where occupancy density is known and documented in the plans, the outside air rate may be based on the design occupant density. Under no circumstance shall the occupancies used result in outside air less than one-half that resulting from application of Table 3-4 estimated maximum occupancy values.

     The outdoor air shall be ducted in a fully enclosed path directly to every air handling unit in each zone not provided with sufficient operable area for natural ventilation.

EXCEPTION:

Ducts may terminate within 12 inches of the intake to an HVAC unit provided they are physically fastened so that the outside air duct is directed into the unit intake.

     In all parking garages, other than open parking garages as defined in UBC 311.9, used for storing or handling of automobiles operating under their own power and on all loading platforms in bus terminals, ventilation shall be provided at 1.5 cfm per square foot of gross floor area.      The building official may approve an alternate ventilation system designed to exhaust a minimum fourteen thousand cfm for each operating vehicle.      Such system shall be based on the anticipated instantaneous movement rate of vehicles but not less than 2.5 percent (or one vehicle) of the garage capacity.      Automatic carbon monoxide sensing systems may be submitted for approval.

     In all buildings used for the repair of automobiles, each repair stall shall be equipped with an exhaust extension duct, extending to the outside of the building, which if over ten feet in length, shall mechanically exhaust three hundred cfm.      Connecting offices and waiting rooms shall be supplied with conditioned air under positive pressure.

     Combustion air requirements shall conform to the requirements of Chapter 7 of the UMC.

     Mechanical refrigerating equipment and rooms storing refrigerants shall conform to the requirements of Chapter 11 of the UMC.

     304.2 Alternate Systems: Alternate systems designed in accordance with ASHRAE Standard 62.1.1999 shall be permitted.

TABLE 3-1

Minimum Source Specific Ventilation Capacity

Requirements

((TABLE 3-2

Whole House Ventilation Flow Requirements¹

TABLE 3-2

Ventilation Rates For All Group R occupancies four (4) stories and less*

Minimum and Maximum Ventilation Rates: Cubic Feet Per Minute (CFM)

TABLE 3-3

Prescriptive Exhaust Duct Sizing

[TABLE 3-4

OUTDOOR AIR REQUIREMENTS FOR VENTILATION¹

OCCUPANCIES NOT SUBJECT TO SECTION 302

TABLE 3-4

Outdoor air requirements for ventilation¹

Occupancies not subject to sections 302 and 303

1.	Derived from ASHRAE Standard 62-1989.
2.	Net occupiable space.
3.	Dry-cleaning process may require more air.
4.	Supplementary smoke-removal equipment may be required.
5.	Distribution among people must consider worker location and concentration of running engine; stands where engines are run must incorporate systems for positive engine exhaust withdrawal. Contaminant sensors may be used to control ventilation.
6.	Independent of room size.
7.	Installed capacity for intermittent use.
8.	See also food and beverage service, merchandising, barber and beauty shops, garages.
9.	Some office equipment may require local exhaust.
10.	Mechanical exhaust with no recirculation is recommended.
11.	Normally supplied by transfer air, local mechanical exhaust; with no recirculation recommended.
12.	Normally supplied by transfer air.
13.	Ventilation to optimize plant growth may dictate requirements.
14.	When internal combustion engines are operated for maintenance of playing surfaces, increased ventilation rates may be required.
15.	Higher values may be required for humidity control.
16.	Special ventilation will be needed to eliminate special stage effects.
17.	Ventilation within vehicles may require special considerations.
18.	Spaces maintained at low temperatures (-10°F. to+ 50°F.) are not covered by these requirements unless the occupancy is continuous. Ventilation from adjoining spaces is permissible. When the occupancy is intermittent, infiltration will normally exceed the ventilation requirements.
19.	Installed equipment must incorporate positive exhaust and control of undesirable contaminants.
20.	Special contamination control systems may be required for processes or functions including laboratory animal occupancy.
21.	Special requirements or codes and pressure relationships may determine minimum ventilation rates and filter efficiency. Procedures generating contaminants may require higher rates.
22.	Air shall not be recirculated into other spaces.
23.	Makeup air for hood exhaust may require more ventilating air.
24.	Occupant loading shall be based on the number of bedrooms as follows: first bedroom, two persons; each additional bedroom, one person. Where higher occupant loadings are known, they shall be used.

TABLE 3-5

Prescriptive Integrated Forced Air Supply Duct Sizing

TABLE 3-6

Prescriptive Supply Fan Duct Sizing

[Statutory Authority: RCW 19.27.190.      95-01-128, § 51-13-304, filed 12/21/94, effective 6/30/95.      Statutory Authority: RCW 19.27.190(2) and 1992 c 132.      93-02-056, § 51-13-304, filed 1/6/93, effective 7/1/93.      Statutory Authority: RCW 19.27.190.      91-01-102, § 51-13-304, filed 12/18/90, effective 7/1/91.]

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 93-02-056, filed 1/6/93, effective 7/1/93)

WAC 51-13-503
Radon prescriptive requirements.

     503.1 Scope: This section applies to those counties specified in section 501.2.2.      This section establishes prescriptive construction requirements for reducing the potential for radon entry into all Group R occupancies, and for preparing the building for future mitigation if desired.

     In all crawlspaces, except crawlspace plenums used for providing supply air for an HVAC system, a continuous air barrier shall be installed between the crawlspace area and the occupied area to limit air transport between the areas.      If a wood sheet subfloor or other material is utilized as an air barrier, in addition to the requirements of section 502.1.6.2 of the Washington state energy code, all joints between sheets shall be sealed.

     503.2 Floors in Contact with the Earth

     503.2.1 General: Concrete slabs that are in direct contact with the building envelope shall comply with the requirements of this section.

EXCEPTION:

Concrete slabs located under garages or other than Group R occupancies need not comply with this chapter.

     503.2.2 Aggregate: A layer of aggregate of four inch minimum thickness shall be placed beneath concrete slabs.      The aggregate shall be continuous to the extent practical.

     503.2.3 Gradation: Aggregate shall:

     a) Comply with ASTM Standard C-33 Standard Specification for Concrete Aggregate and shall be size No. ((67)) 8 or larger size aggregate as listed in Table 2, Grading Requirements for Coarse Aggregate; or

     b) Meet the 1988 Washington State Department of Transportation specification 9-03.1 (3) "Coarse Aggregate for Portland Cement Concrete", or any equivalent successor standards. Aggregate size shall be of Grade ((5)) 8 or larger as listed in section 9-03.1 (3) C, "Grading"; or

     c) Be screened, washed((, and)) pea gravel free of deleterious substances in a manner consistent with ASTM Standard C-33 with one hundred percent ((of the gravel)) (100%) passing a one-half (1/2) inch sieve and less than ((two)) five percent (5%) passing a ((four-inch)) No. 16 sieve.      Sieve characteristics shall conform to those acceptable under ASTM Standard C-33.

EXCEPTION:

Aggregate shall not be required if a substitute material or system, with sufficient load bearing characteristics, and having approved capability to provide equal or superior air flow, is installed.

     503.2.4 Soil-Gas Retarder Membrane: A soil-gas retarder membrane, consisting of at least one layer of virgin polyethylene with a thickness of at least six mil, or equivalent flexible sheet material, shall be placed directly ((under all concrete slabs so that the slab is in direct contact with the)) on top of the aggregate. Two inches (2") minimum of fine sand or pea gravel shall be installed between the concrete slab and membrane.      The flexible sheet shall extend to the foundation wall or to the outside edge of the monolithic slab.      Seams shall overlap at least twelve inches. The membrane shall also be fitted tightly to all pipes, wires, and other penetrations of the membrane and sealed with an approved sealant or tape. All punctures or tears shall be repaired with the same or approved material and similarly lapped and sealed.

((EXCEPTION:

If the membrane is not in direct contact with the bottom of the concrete slab, all overlapping seams shall be sealed with an approved tape or sealant, and the material shall be sealed to the foundation wall in a permanent manner.      The membrane shall also be fitted tightly to all pipes, wires, and other penetrations of the membrane and sealed with an approved sealant or tape.      All punctures or tears shall be repaired with the same or approved material and similarly lapped and sealed.      In no case shall the membrane be installed below the aggregate.))

     503.2.5 Sealing of Penetrations and Joints: All penetrations and joints in concrete slabs or other floor systems and walls below grade shall be sealed by an approved sealant to create an air barrier to limit the movement of soil-gas into the indoor air.

     Sealants shall be approved by the manufacturer for the intended purpose.      Sealant joints shall conform to manufacturer's specifications.      The sealant shall be placed and tooled in accordance with manufacturer's specifications.      There shall be no gaps or voids after the sealant has cured.

     c. Radon removal systems for slabs over 3000 sq. ft. shall require approval.

     The perforated pipe shall remain in the aggregate area and shall not be capped at the ends. The "T" and it's perforated pipe extensions shall be located at least five feet horizontally from the exterior perimeter of the aggregate area.

     The continuous sealed pipe shall terminate no less than twelve inches above the eave, and more than ten horizontal feet from a woodstove or fireplace chimney, or operable window.      The continuous sealed pipe shall be permanently labeled "radon vent((.))" ((The)) on each floor and attic space. At least one label shall be placed so as to remain visible to an occupant.

     The minimum pipe diameter shall be three inches for a slab with less than 750 sq. ft. and four inches for a slab 750 to 3000 sq. ft. unless otherwise approved.      Slabs larger than 3000 sq. ft. shall require approval. Acceptable sealed plastic pipe shall be smooth walled, and may include either PVC schedule 40 or ABS schedule of equivalent wall thickness.

     The entire sealed pipe system shall be sloped to drain to the sub-slab aggregate.     

     The sealed pipe system may pass through an unconditioned attic before exiting the building; but to the extent practicable, the sealed pipe shall be located inside the thermal envelope of the building in order to enhance passive stack venting.

EXCEPTION:

A fan forced sub-slab depressurization system includes:

	1) Soil-gas retarder membrane as specified in section 503.2.4;
	2) Sealing of penetrations and joints as specified in section 503.2.5;
	3) A ((three-inch)) continuous sealed radon pipe shall run from a point within the aggregate under each concrete slab to a point outside the building;
	4) Joints and connections may be gas tight, and may be of either PVC schedule 40 or ABS schedule of equivalent in wall thickness;
	5) A label of "radon vent" on each floor and attic space shall be placed on the pipe so ((as to remain)) at least one label remains visible to the occupant;
	6) Fan circuit and wiring as specified in section 503.2.7 and a fan.

     If the sub-slab depressurization system is exhausted through the concrete foundation wall or rim joist, the exhaust terminus shall be a minimum of six feet from operable windows or outdoor air intake vents and shall be directed away from operable windows and outdoor air intake vents to prevent radon re-entrainment.

     503.2.7 Fan Circuit and Wiring and Location: An area for location of an in-line fan shall be provided.      The location shall be as close as practicable to the radon vent pipe's point of exit from the building, or shall be outside the building shell; and shall be located so that the fan and all downstream piping is isolated from the indoor air.

     Provisions shall be made to allow future activation of an in-line fan on the radon vent pipe without the need to place new wiring.      A one hundred ten volt power supply shall be provided at a junction box near the fan location.

     503.2.8 Separate Aggregate Areas: If the four-inch aggregate area underneath the concrete slab is not continuous, but is separated into distinct isolated aggregate areas by a footing or other barrier, a minimum of one radon vent pipe shall be installed into each separate aggregate area.

EXCEPTION:

Separate aggregate areas may be considered a single area if a minimum ((three-inch diameter)) of a twelve (12) square inch connection joining the separate areas is provided for every ((thirty feet)) ten (10) linear feet, or fraction thereof, of barrier separating those areas. The connection shall be constructed to allow air flow and remain free from obstruction.

     503.2.9 Concrete Block Walls: Concrete block walls connected to below grade areas shall be considered unsealed surfaces.      All openings in concrete block walls that will not remain accessible upon completion of the building shall be sealed at both vertical and horizontal surfaces, in order to create a continuous air barrier to limit the transport of soil-gas into the indoor air.

     503.3 Radon Crawlspace Ventilation: A radon vent shall be installed in crawlspaces originating from a point between the ground cover (see WAC Section 502.1.6.7) and soil. The radon vent shall be installed in accordance with Sections 503.2.6 and 503.2.7. Radon vents shall comply with the following:

     a. Three (3) inch minimum radon vent pipe for crawlspaces 750 square feet or less,

     b. Four (4) inch minimum radon vent pipe for crawlspaces between 750 and 3000 square feet, or

     c. Radon removal systems for crawlspaces over 3000 square feet shall require approval.

[Statutory Authority: RCW 19.27.190(2) and 1992 c 132.      93-02-056, § 51-13-503, filed 1/6/93, effective 7/1/93.      Statutory Authority: RCW 19.27.190.      91-01-102, § 51-13-503, filed 12/18/90, effective 7/1/91.]

     503.1 Scope: This section applies to those counties specified in section 501.2.2.      This section establishes prescriptive construction requirements for reducing the potential for radon entry into all Group R occupancies, and for preparing the building for future mitigation if desired.

     In all crawlspaces, except crawlspace plenums used for providing supply air for an HVAC system, a continuous air barrier shall be installed between the crawlspace area and the occupied area to limit air transport between the areas.      If a wood sheet subfloor or other material is utilized as an air barrier, in addition to the requirements of section 502.1.6.2 of the Washington state energy code, all joints between sheets shall be sealed.

     503.2 Floors in Contact with the Earth

     503.2.1 General: Concrete slabs that are in direct contact with the building envelope shall comply with the requirements of this section.

EXCEPTION:

Concrete slabs located under garages or other than Group R occupancies need not comply with this chapter.

     503.2.2 Aggregate: A layer of aggregate of four inch minimum thickness shall be placed beneath concrete slabs.      The aggregate shall be continuous to the extent practical.

     503.2.3 Gradation: Aggregate shall:

     a) Comply with ASTM Standard C-33 Standard Specification for Concrete Aggregate and shall be size No. ((67)) 8 or larger size aggregate as listed in Table 2, Grading Requirements for Coarse Aggregate; or

     b) Meet the 1988 Washington State Department of Transportation specification 9-03.1 (3) "Coarse Aggregate for Portland Cement Concrete", or any equivalent successor standards. Aggregate size shall be of Grade ((5)) 8 or larger as listed in section 9-03.1 (3) C, "Grading"; or

     c) Be screened, washed((, and)) pea gravel free of deleterious substances in a manner consistent with ASTM Standard C-33 with one hundred percent ((of the gravel)) (100%) passing a one-half (1/2) inch sieve and less than ((two)) five percent (5%) passing a ((four-inch)) No. 16 sieve.      Sieve characteristics shall conform to those acceptable under ASTM Standard C-33.

EXCEPTION:

Aggregate shall not be required if a substitute material or system, with sufficient load bearing characteristics, and having approved capability to provide equal or superior air flow, is installed.

     503.2.4 Soil-Gas Retarder Membrane: A soil-gas retarder membrane, consisting of at least one layer of virgin polyethylene with a thickness of at least six mil, or equivalent flexible sheet material, shall be placed directly ((under all concrete slabs so that the slab is in direct contact with the)) on top of the aggregate. Two inches (2") minimum of fine sand or pea gravel shall be installed between the concrete slab and membrane.      The flexible sheet shall extend to the foundation wall or to the outside edge of the monolithic slab.      Seams shall overlap at least twelve inches. The membrane shall also be fitted tightly to all pipes, wires, and other penetrations of the membrane and sealed with an approved sealant or tape. All punctures or tears shall be repaired with the same or approved material and similarly lapped and sealed.

((EXCEPTION:

If the membrane is not in direct contact with the bottom of the concrete slab, all overlapping seams shall be sealed with an approved tape or sealant, and the material shall be sealed to the foundation wall in a permanent manner.      The membrane shall also be fitted tightly to all pipes, wires, and other penetrations of the membrane and sealed with an approved sealant or tape.      All punctures or tears shall be repaired with the same or approved material and similarly lapped and sealed.      In no case shall the membrane be installed below the aggregate.))

     503.2.5 Sealing of Penetrations and Joints: All penetrations and joints in concrete slabs or other floor systems and walls below grade shall be sealed by an approved sealant to create an air barrier to limit the movement of soil-gas into the indoor air.

     Sealants shall be approved by the manufacturer for the intended purpose.      Sealant joints shall conform to manufacturer's specifications.      The sealant shall be placed and tooled in accordance with manufacturer's specifications.      There shall be no gaps or voids after the sealant has cured.

     c. Radon removal systems for slabs over 3000 sq. ft. shall require approval.

     The perforated pipe shall remain in the aggregate area and shall not be capped at the ends. The "T" and it's perforated pipe extensions shall be located at least five feet horizontally from the exterior perimeter of the aggregate area.

     The continuous sealed pipe shall terminate no less than twelve inches above the eave, and more than ten horizontal feet from a woodstove or fireplace chimney, or operable window.      The continuous sealed pipe shall be permanently labeled "radon vent((.))" ((The)) on each floor and attic space. At least one label shall be placed so as to remain visible to an occupant.

     The minimum pipe diameter shall be three inches for a slab with less than 750 sq. ft. and four inches for a slab 750 to 3000 sq. ft. unless otherwise approved.      Slabs larger than 3000 sq. ft. shall require approval. Acceptable sealed plastic pipe shall be smooth walled, and may include either PVC schedule 40 or ABS schedule of equivalent wall thickness.

     The entire sealed pipe system shall be sloped to drain to the sub-slab aggregate.     

     The sealed pipe system may pass through an unconditioned attic before exiting the building; but to the extent practicable, the sealed pipe shall be located inside the thermal envelope of the building in order to enhance passive stack venting.

((EXCEPTION:

A fan forced sub-slab depressurization system includes:

	1) Soil-gas retarder membrane as specified in section 503.2.4;
	2) Sealing of penetrations and joints as specified in section 503.2.5;
	3) A three-inch continuous sealed radon pipe shall run from a point within the aggregate under each concrete slab to a point outside the building;
	4) Joints and connections may be gas tight, and may be of either PVC schedule 40 or ABS schedule of equivalent in wall thickness;
	5) A label of "radon vent" shall be placed on the pipe so as to remain visible to the occupant;
	6) Fan circuit and wiring as specified in section 503.2.7 and a fan.

     If the sub-slab depressurization system is exhausted through the concrete foundation wall or rim joist, the exhaust terminus shall be a minimum of six feet from operable windows or outdoor air intake vents and shall be directed away from operable windows and outdoor air intake vents to prevent radon re-entrainment.))

     503.2.7 Fan Circuit and Wiring and Location: An area for location of an in-line fan shall be provided.      The location shall be as close as practicable to the radon vent pipe's point of exit from the building, or shall be outside the building shell; and shall be located so that the fan and all downstream piping is isolated from the indoor air.

     Provisions shall be made to allow future activation of an in-line fan on the radon vent pipe without the need to place new wiring.      A one hundred ten volt power supply shall be provided at a junction box near the fan location.

     503.2.8 Separate Aggregate Areas: If the four-inch aggregate area underneath the concrete slab is not continuous, but is separated into distinct isolated aggregate areas by a footing or other barrier, a minimum of one radon vent pipe shall be installed into each separate aggregate area.

EXCEPTION:

Separate aggregate areas may be considered a single area if a minimum ((three-inch diameter)) of a twelve (12) square inch connection joining the separate areas is provided for every ((thirty feet)) ten (10) linear feet, or fraction thereof, of barrier separating those areas. The connection shall be constructed to allow air flow and remain free from obstruction.

     503.2.9 Concrete Block Walls: Concrete block walls connected to below grade areas shall be considered unsealed surfaces.      All openings in concrete block walls that will not remain accessible upon completion of the building shall be sealed at both vertical and horizontal surfaces, in order to create a continuous air barrier to limit the transport of soil-gas into the indoor air.

     503.3 Radon Crawlspace Ventilation: A radon vent shall be installed in crawlspaces originating from a point between the ground cover (see WAC Section 502.1.6.7) and soil. The radon vent shall be installed in accordance with Sections 503.2.6 and 503.2.7. Radon vents shall comply with the following:

     a. Three (3) inch minimum radon vent pipe for crawlspaces 750 square feet or less,

     b. Four (4) inch minimum radon vent pipe for crawlspaces between 750 and 3000 square feet, or

     c. Radon removal systems for crawlspaces over 3000 square feet shall require approval.

[Statutory Authority: RCW 19.27.190(2) and 1992 c 132.      93-02-056, § 51-13-503, filed 1/6/93, effective 7/1/93.      Statutory Authority: RCW 19.27.190.      91-01-102, § 51-13-503, filed 12/18/90, effective 7/1/91.]

© Washington State Code Reviser's Office