PERMANENT RULES
Date of Adoption: November 17, 2000.
Purpose: To make changes to the Washington State Ventilation and Indoor Air Quality Code, chapter 51-13 WAC.
Citation of Existing Rules Affected by this Order: Amending chapter 51-13 WAC, Sections 101, 301, 302, 303, 304, 503.
Statutory Authority for Adoption: RCW 19.27.190, 19.27.020.
Adopted under notice filed as WSR 00-18-016 on August 28, 2000.
Changes Other than Editing from Proposed to Adopted Version: The proposed amendments to the following sections were not adopted: (302.2.1 and 303.3.1), 303.4.2.1, (503.2.6 and new section 503.4), 503.2.8 and 503.3. In addition, the proposal to amend Section 503.2.4 relocating the soil-gas retarder membrane from "directly under the slab" to "directly on top of the aggregate and under a two inch layer of sand gravel" was altered to allow two options so either construction method will comply with the rule.
Number of Sections Adopted in Order to Comply with Federal Statute: New 0, Amended 0, Repealed 0; Federal Rules or Standards: New 0, Amended 0, Repealed 0; or Recently Enacted State Statutes: New 0, Amended 0, Repealed 0.
Number of Sections Adopted at Request of a Nongovernmental Entity: New 0, Amended 6, Repealed 0.
Number of Sections Adopted on the Agency's Own Initiative: New 0, Amended 0, Repealed 0.
Number of Sections Adopted in Order to Clarify, Streamline, or Reform Agency Procedures: New 0, Amended 0, Repealed 0.
Number of Sections Adopted Using Negotiated Rule Making: New 0, Amended 0, Repealed 0; Pilot Rule Making: New 0, Amended 0, Repealed 0; or Other Alternative Rule Making: New 0, Amended 6, Repealed 0. Effective Date of Rule: July 1, 2001.
January 3, 2001
Tim Nogler
for Jim Lewis
Council Vice Chair
OTS-4216.3
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.
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)) 302.1.2 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,
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.
((302.3)) 302.3.2 Whole House Ventilation System Controls:
All ventilation system controls shall be readily accessible. Controls for whole house ventilation systems shall be capable of
operating the ventilation system without energizing other
energy-consuming appliances.
((
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, 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. |
303.3.4 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.
303.4.1.3 Fan Controls: The whole house ventilation fan
shall be controlled by a 24 hour clock timer with the capability
of continuous operation, manual and automatic control. The
24-hour timer shall be readily accessible. The 24 hour timer
shall be capable of operating the whole house ventilation fan
without energizing other energy-consuming appliances. At the
time of final inspection, the automatic control timer shall be
set to operate the whole house fan for at least eight hours a
day. A label shall be affixed to the control that reads "Whole
House Ventilation (see operating instructions)."
303.4.1.4 Exhaust Ducts: All exhaust 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.
303.4.1.5 Outdoor Air Inlets: Outdoor air shall be
distributed to each habitable room by individual outdoor air
inlets. 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.
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 (HVI 901 (November 1996)) are deemed equivalent to four square inches net free area.
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:
a. Closer than 10 feet from an appliance vent outlet, unless such vent outlet is 3 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 10 feet from a vent opening of a plumbing drainage system unless the vent opening is at least 3 feet above the air inlet.
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. |
303.4.2.1 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; or
2. A damper installed and set to meet minimum 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 of 0.07 inches water gauge at the point where the outside air duct is connected to the return air plenum.
303.4.2.2 Ventilation Controls: The whole house ventilation
system shall be controlled by a 24 hour clock timer with the
capability of continuous operation, manual and automatic control.
This control will control the forced air system blower and if
applicable the automatic damper. The 24-hour timer shall be
readily accessible. The 24 hour timer shall be capable of
operating the whole house ventilation system without energizing
other energy-consuming appliances. At the time of final
inspection, the automatic control timer shall be set to operate
the whole house system for at least eight hours a day. A label
shall be affixed to the control that reads "Whole House
Ventilation (see operating instructions)."
303.4.2.3 Ventilation Duct Insulation: All supply ducts in
the conditioned space shall be insulated to a minimum of R-4.
303.4.2.4 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:
a. Closer than 10 feet from an appliance vent outlet, unless such vent outlet is 3 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 10 feet from a vent opening of a plumbing drainage system unless the vent opening is at least 3 feet above the air inlet.
f. Attic, crawl spaces, or garages.
303.4.3 Prescriptive Requirements for Intermittent Whole
House Ventilation Using a Supply Fan: This section establishes
minimum prescriptive requirements for intermittent 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.
303.4.3.1 Outdoor Air: Supply Fan Ventilation Systems shall
distribute outdoor air to each habitable room through the
forced-air system ducts or through dedicated ducts to each
habitable room. Supply fans shall have the capacity to provide
the amount of outdoor air specified in Table 3-2 at 0.4 inches
water gauge as per HVI 916 (April 1995). The outdoor air must be
filtered before it is delivered to habitable rooms. The filter
may be located at the intake device, inline with the fan, or, in
the case of a connection to the return plenum of the airhandler,
using the furnace filter. An outdoor air inlet shall be
connected to either the supply or return air stream.
303.4.3.2 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 four 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
3-6. The terminal element on the outside of the building shall
be sized two inches in diameter larger than the outdoor air inlet
duct.
303.4.3.3 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 3-2 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 3-2 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 3-2 which provides constant flow over a pressure range of 0.2 to 0.6 inches water gauge.
303.4.3.4 Ventilation Controls: The whole house ventilation
system shall be controlled by a 24 hour clock timer with the
capability of continuous operation, manual and automatic control.
This control will control the inline supply fan. The 24-hour
timer shall be readily accessible. The 24 hour timer shall be
capable of operating the whole house ventilation system without
energizing other energy-consuming appliances. At the time of
final inspection, the automatic control timer shall be set to
operate the whole house system for at least eight hours a day. A
label shall be affixed to the control that reads "Whole House
Ventilation (see operating instructions)."
303.4.3.5 Ventilation Duct Insulation: All supply ducts in
the conditioned space shall be insulated to a minimum of R-4.
303.4.3.6 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:
a. Closer than 10 feet from an appliance vent outlet, unless such vent outlet is 3 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 10 feet from a vent opening of a plumbing drainage system unless the vent opening is at least 3 feet above the air inlet.
f. Attic, crawl spaces, or garages.
303.4.4 Prescriptive Requirements for Intermittent Whole
House Ventilation Using a Heat Recovery Ventilation System: This
section establishes minimum prescriptive requirements for
intermittent whole house ventilation using a heat recovery
ventilation system.
303.4.4.1 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.
303.4.4.2 Ventilation Controls: The whole house ventilation
system shall be controlled by a 24 hour clock timer with the
capability of continuous operation, manual and automatic control.
This control will control the inline supply fan. The 24-hour
timer shall be readily accessible. The 24 hour timer shall be
capable of operating the whole house ventilation system without
energizing other energy-consuming appliances. At the time of
final inspection, the automatic control timer shall be set to
operate the whole house system for at least eight hours a day. A
label shall be affixed to the control that reads "Whole House
Ventilation (see operating instructions)."
303.4.4.3 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.
303.4.4.4 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:
a. Closer than 10 feet from an appliance vent outlet, unless such vent outlet is 3 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 10 feet from a vent opening of a plumbing drainage system unless the vent opening is at least 3 feet above the air inlet.
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
| Bathrooms | Kitchens | |
| Intermittently operating | 50 cfm | 100 cfm |
| Continuous operation | 20 cfm | 25 cfm |
((TABLE 3-2
Whole House Ventilation Flow Requirements1
| 180)) | ||
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)
| Floor Area, ft2 |
Bedrooms | |||||||||||||
| 2 or less | 3 | 4 | 5 | 6 | 7 | 8 | ||||||||
| Min. | Max. | Min. | Max. | Min. | Max. | Min. | Max. | Min. | Max. | Min. | Max. | Min. | Max. | |
| <500 | 50 | 75 | 65 | 98 | 80 | 120 | 95 | 143 | 110 | 165 | 125 | 188 | 140 | 210 |
| 501-1000 | 55 | 83 | 70 | 105 | 85 | 128 | 100 | 150 | 115 | 173 | 130 | 195 | 145 | 218 |
| 1001-1500 | 60 | 90 | 75 | 113 | 90 | 135 | 105 | 158 | 120 | 180 | 135 | 203 | 150 | 225 |
| 1501-2000 | 65 | 98 | 80 | 120 | 95 | 143 | 110 | 165 | 125 | 188 | 140 | 210 | 155 | 233 |
| 2001-2500 | 70 | 105 | 85 | 128 | 100 | 150 | 115 | 173 | 130 | 195 | 145 | 218 | 160 | 240 |
| 2501-3000 | 75 | 113 | 90 | 135 | 105 | 158 | 120 | 180 | 135 | 203 | 150 | 225 | 165 | 248 |
| 3001-3500 | 80 | 120 | 95 | 143 | 110 | 165 | 125 | 188 | 140 | 210 | 155 | 233 | 170 | 255 |
| 3501-4000 | 85 | 128 | 100 | 150 | 115 | 173 | 130 | 195 | 145 | 218 | 160 | 240 | 175 | 263 |
| 4001-5000 | 95 | 143 | 110 | 165 | 125 | 188 | 140 | 210 | 155 | 233 | 170 | 255 | 185 | 278 |
| 5001-6000 | 105 | 158 | 120 | 180 | 135 | 203 | 150 | 225 | 165 | 248 | 180 | 270 | 195 | 293 |
| 6001-7000 | 115 | 173 | 130 | 195 | 145 | 218 | 160 | 240 | 175 | 263 | 190 | 285 | 205 | 308 |
| 7001-8000 | 125 | 188 | 140 | 210 | 155 | 233 | 170 | 255 | 185 | 278 | 200 | 300 | 215 | 323 |
| 8001-9000 | 135 | 203 | 150 | 225 | 165 | 248 | 180 | 270 | 195 | 293 | 210 | 315 | 225 | 338 |
| >9000 | 145 | 218 | 160 | 240 | 175 | 263 | 190 | 285 | 205 | 308 | 220 | 330 | 235 | 353 |
| *For residences that exceed 8 bedrooms, increase the minimum requirement listed for 8 bedrooms by an additional 15 CFM per bedroom. The maximum CFM is equal to 1.5 times the minimum. | ||||||||||||||
TABLE 3-3
Prescriptive Exhaust Duct Sizing
| Fan
Tested CFM @ 0.25 W.G. |
Minimum Flex Diameter |
Maximum Length Feet |
Minimum Smooth Diameter |
Maximum Length Feet |
Maximum Elbows1 |
| 50 | 4 inch | 25 | 4 inch | 70 | 3 |
| 50 | 5 inch | 90 | 5 inch | 100 | 3 |
| 50 | 6 inch | No Limit | 6 inch | No Limit | 3 |
| 80 | 4 inch2 | NA | 4 inch | 20 | 3 |
| 80 | 5 inch | 15 | 5 inch | 100 | 3 |
| 80 | 6 inch | 90 | 6 inch | No Limit | 3 |
| 100 | 5 inch2 | NA | 5 inch | 50 | 3 |
| 100 | 6 inch | 45 | 6 inch | No Limit | 3 |
| 125 | 6 inch | 15 | 6 inch | No Limit | 3 |
| 125 | 7 inch | 70 | 7 inch | No Limit | 3 |
| 1. | For each additional elbow subtract 10 feet from length. |
| 2. | Flex ducts of this diameter are not permitted with fans of this size. |
TABLE 3-4
Outdoor air requirements for ventilation1
Occupancies not subject to sections 302 and 303
| Application | Estimated Maximum2Occupancy P/1000 ft2 or 100 m2 |
Outdoor Air Requirements cfm/person |
| Dry Cleaners, Laundries3 | ||
| Commercial laundry | 10 | 25 |
| Commercial dry cleaner | 30 | 30 |
| Storage, pick up | 30 | 35 |
| Coin-operated laundries | 20 | 15 |
| Coin-operated dry cleaner | 20 | 15 |
| Dwelling Units In Buildings Greater Than Four Stories or Attached to I- Occupancy Facilities |
||
| Bedroom & living area24 | 15 | |
| Food and Beverage Service | ||
| Dining rooms | 70 | 20 |
| Cafeteria, fast food | 100 | 20 |
| Bars, cocktail lounges4 | 100 | 30 |
| Kitchens (cooking)23 | 20 | 15 |
| Garages, Repair, Service Stations | ||
| Enclosed parking garage5 | 1.50 cfm/ft.sq. | |
| Auto repair rooms | 1.50 cfm/ft.sq. | |
| Hotels, Motels, Resorts, Congregate Residences with More Than Four Stories6 |
||
| Bedrooms | 30 cfm/room | |
| Living Rooms | 30 cfm/room | |
| Bath7 | 35 cfm/room | |
| Lobbies | 30 | 15 |
| Conference rooms | 50 | 20 |
| Assembly rooms | 120 | 15 |
| Gambling casinos4 | 120 | 30 |
| Offices | ||
| Office space9 | 7 | 20 |
| Reception area | 60 | 15 |
| Telecommunication centers and data entry areas |
60 | 20 |
| Conference rooms | 50 | 20 |
| Public Spaces | ||
| Corridors and utilities | 0.05 cfm/ft.sq. | |
| Public restroom, cfm/wc or urinal10 |
50 | |
| Lockers and dressing rooms | 0.50 cfm/ft.sq. | |
| Smoking lounge11 | 70 | 60 |
| Elevators12 | 1.0 cfm/ft.sq. | |
| Retail Stores, Sales Floors, and Show Room Floors | ||
| Basement and street | 30 | 0.30 cfm/ft.sq. |
| Upper floors | 20 | 0.20 cfm/ft.sq. |
| Storage rooms | 15 | 0.15 cfm/ft.sq. |
| Dressing rooms | 0.20 cfm/ft.sq. | |
| Malls and arcades | 20 | 0.20 cfm/ft.sq. |
| Shipping and receiving | 10 | 0.15 cfm/ft.sq. |
| Smoking lounge11 | 70 | 60 |
| Warehouses | 5 | 0.05 cfm/ft.sq. |
| Speciality Shops | ||
| Barber | 25 | 15 |
| Beauty | 25 | 25 |
| Reducing salons | 20 | 15 |
| Florists13 | 8 | 15 |
| Clothiers, furniture | 0.30 cfm/ft.sq. | |
| Hardware, drugs, fabric | 8 | 15 |
| Supermarkets | 8 | 15 |
| Pet shops | 1.00 cfm/ft.sq. | |
| Sports and Amusement14 | ||
| Spectator areas | 150 | 15 |
| Game rooms | 70 | 25 |
| Ice arenas (playing areas) | 0.50 cfm/ft.sq. | |
| Swimming Pools (pool and deck area)15 |
0.50 cfm/ft.sq. | |
| Playing floor (gymnasium) | 30 | 20 |
| Ballrooms and discos | 100 | 25 |
| Bowling alleys (seating areas) | 70 | 25 |
| Theaters16 | ||
| Ticket booths | 60 | 20 |
| Lobbies | 150 | 20 |
| Auditorium | 150 | (( |
| Stages, studios | 70 | 15 |
| Transportation17 | ||
| Waiting rooms | 100 | 15 |
| Platforms | 100 | 15 |
| Vehicles | 150 | 15 |
| Workrooms | ||
| Meat processing18 | 10 | 15 |
| Photo studios | 10 | 15 |
| Darkrooms | 10 | 0.50 cfm/ft.sq. |
| Pharmacy | 20 | 15 |
| Bank vaults | 5 | 15 |
| Duplicating, printing19 | 0.50 cfm/ft.sq. | |
| INSTITUTIONAL FACILITIES | ||
| Education | ||
| Classroom | 50 | 15 |
| Laboratories20 | 30 | 20 |
| Training shop | 30 | 20 |
| Music rooms | 50 | 15 |
| Libraries | 20 | 15 |
| Locker rooms | 0.50 cfm/ft.sq. | |
| Corridors | 0.10 cfm/ft.sq. | |
| Auditoriums | 150 | 15 |
| Smoking lounges11 | 70 | 60 |
| Hospitals, Nursing and Convalescent Homes | ||
| Patient rooms21 | 10 | 25 |
| Medical procedure | 20 | 15 |
| Operating rooms | 20 | 30 |
| Recovery and ICU | 20 | 15 |
| Autopsy rooms22 | 0.50 cfm/ft.sq. | |
| Physical Therapy | 20 | 15 |
| Correctional Facilities | ||
| Cells | 20 | 20 |
| Dining halls | 100 | 15 |
| Guard station | 40 | 15 |
| 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
Bedrooms |
Smooth Duct Diameter |
Flexible Duct Diameter |
Length1 |
Number of Elbows2 |
| 3)) | ||||
| Required Flow (CFM) Per Table 3-2 |
Minimum Smooth Duct Diameter |
Minimum Flexible Duct Diameter |
Maximum Length1 |
Maximum Number of Elbows2 |
| 50-80 | 6" | 7" | 20' | 3 |
| 80-125 | 7" | 8" | 20' | 3 |
| 115-175 | 8" | 10" | 20' | 3 |
| 170-240 | 9" | 11" | 20' | 3 |
| 1. | For lengths over 20 feet increase duct diameter 1 inch. |
| 2. | For elbows numbering more than 3 increase duct diameter 1 inch. |
| Supply Fan Tested CFM At 0.4" WG | ||
| Specified volume from Table 3-2 |
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 |
[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.]
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 either placed directly under all
concrete slabs so that the slab is in direct contact with the
membrane, or on top of the aggregate with two inches (2") minimum
of fine sand or pea gravel 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.
503.2.6 Radon Vent: One continuous sealed pipe shall run
from a point within the aggregate under each concrete slab to a
point outside the building. Joints and connections shall be
permanently gas tight. The continuous sealed pipe shall
interface with the aggregate in the following manner, or by other
approved equal method: The pipe shall be permanently connected
to a "T" within the aggregate area so that the two end openings
of the "T" lie within the aggregate area. A minimum of five feet
of perforated drain pipe of three inches minimum diameter shall
join to and extend from the "T."
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 labeled "radon vent." The label
shall be placed so as to remain visible to an occupant.
The minimum pipe diameter shall be three inches unless
otherwise approved. 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. |
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 connection joining
the separate areas is provided for every thirty feet of barrier separating those areas.
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.
[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.]