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Chapter 44 — REFERENCED STANDARDS

Section AF102

California Residential Code (Title 24, Part 2.5) · 2022 edition · updated 2026-09-12 · California

Italicized text is a California amendment to the model code, as printed in the official publication.

AF102.1 General.

For the purpose of these requirements, the terms used shall be defined as follows:

DRAIN TILE LOOP. A continuous length of drain tile or perforated pipe extending around all or part of the internal or external perimeter of a basement or crawl space footing.

RADON GAS. A naturally occurring, chemically inert, radioactive gas that is not detectable by human senses. As a gas, it can move readily through particles of soil and rock, and can

accumulate under the slabs and foundations of homes where it can easily enter into the living space through construction cracks and openings.

SOIL-GAS-RETARDER. A continuous membrane of 6-mil (0.15 mm) polyethylene or other equivalent material used to retard the flow of soil gases into a building.

SUBMEMBRANE DEPRESSURIZATION SYSTEM. A system designed to achieve lower submembrane air pressure relative to crawl space air pressure by use of a vent drawing air from beneath the soil-gas-retarder membrane.

SUBSLAB DEPRESSURIZATION SYSTEM (Active). A system designed to achieve lower subslab air pressure relative to indoor air pressure by use of a fan-powered vent drawing air from beneath the slab.

SUBSLAB DEPRESSURIZATION SYSTEM (Passive). A system designed to achieve lower subslab air pressure relative to indoor air pressure by use of a vent pipe routed through the conditioned space of a building and connecting the subslab area with outdoor air, thereby relying on the convective flow of air upward in the vent to draw air from beneath the slab.

Copyright © 2022 by, or licensed to, International Code Council, Inc. (ALL RIGHTS RESERVED); licensed to California Building Standards Commission pursuant to License Agreement. No further reproductions is authorized. Any unauthorized reproduction or distribution is a violation of the federal copyright act and the license agreement, and subject to civil and criminal penalties thereunder.

APPENDIX AF—RADON CONTROL METHODS

APPENDIX AF-2 2022 CALIFORNIA RESIDENTIAL CODE

Copyright © 2022 by, or licensed to, International Code Council, Inc. (ALL RIGHTS RESERVED); licensed to California Building Standards Commission pursuant to License Agreement. No further reproductions is authorized. Any unauthorized reproduction or distribution is a violation of the federal copyright act and the license agreement, and subject to civil and criminal penalties thereunder.

TABLE AF101.1

ALABAMA Kit Carson Clark Macon Fulton
Calhoun Lake Clearwater Marshall Grant
Clay Larimer Custer Mason Hamilton
Cleburne Las Animas Elmore McDonough Hancock
Colbert Lincoln Fremont McLean Harrison
Coosa Logan Gooding Menard Hendricks
Franklin Mesa Idaho Mercer Henry
Jackson Moffat Kootenai Morgan Howard
Lauderdale Montezuma Latah Moultrie Huntington
Lawrence Montrose Lemhi Ogle Jay
Limestone Morgan Shoshone Peoria Jennings
Madison Otero Valley Piatt Johnson
Morgan Ouray ILLINOIS Pike Kosciusko
Talladega Park Adams Putnam LaGrange
CALIFORNIA Phillips Boone Rock Island Lawrence
Santa Barbara Pitkin Brown Sangamon Madison
Ventura Prowers Bureau Schuyler Marion
COLORADO Pueblo Calhoun Scott Marshall
Adams Rio Blanco Carroll Stark Miami
Arapahoe San Miguel Cass Stephenson Monroe
Baca Summit Champaign Tazewell Montgomery
Bent Teller Coles Vermilion Noble
Boulder Washington De Kalb Warren Orange
Chaffee Weld De Witt Whiteside Putnam
Cheyenne Yuma Douglas Winnebago Randolph
Clear Creek CONNECTICUT Edgar Woodford Rush
Crowley Fairfield Ford INDIANA Scott
Custer Middlesex Fulton Adams Shelby
Delta New Haven Greene Allen St. Joseph
Denver New London Grundy Bartholomew Steuben
Dolores GEORGIA Hancock Benton Tippecanoe
Douglas Cobb Henderson Blackford Tipton
El Paso De Kalb Henry Boone Union
Elbert Fulton Iroquois Carroll Vermillion
Fremont Gwinnett Jersey Cass Wabash
Garfield IDAHO Jo Daviess Clark Warren
Gilpin Benewah Kane Clinton Washington
Grand Blaine Kendall De Kalb Wayne
Gunnison Boise Knox Decatur Wells
Huerfano Bonner La Salle Delaware White
Jackson Boundary Lee Elkhart Whitley
Jefferson Butte Livingston Fayette IOWA
Kiowa Camas Logan Fountain All Counties

(continued)

APPENDIX AF—RADON CONTROL METHODS

Copyright © 2022 by, or licensed to, International Code Council, Inc. (ALL RIGHTS RESERVED); licensed to California Building Standards Commission pursuant to License Agreement. No further reproductions is authorized. Any unauthorized reproduction or distribution is a violation of the federal copyright act and the license agreement, and subject to civil and criminal penalties thereunder.

APPENDIX AF—RADON CONTROL METHODS

TABLE AF101.1—continued

KANSAS Pawnee Monroe Lenawee Pennington
Atchison Phillips Nelson St. Joseph Pipestone
Barton Pottawatomie Pendleton Washtenaw Polk
Brown Pratt Pulaski MINNESOTA Pope
Cheyenne Rawlins Robertson Becker Ramsey
Clay Republic Russell Big Stone Red Lake
Cloud Rice Scott Blue Earth Redwood
Decatur Riley Taylor Brown Renville
Dickinson Rooks Warren Carver Rice
Douglas Rush Woodford Chippewa Rock
Ellis Saline MAINE Clay Roseau
Ellsworth Scott Androscoggin Cottonwood Scott
Finney Sheridan Aroostook Dakota Sherburne
Ford Sherman Cumberland Dodge Sibley
Geary Smith Franklin Douglas Stearns
Gove Stanton Hancock Faribault Steele
Graham Thomas Kennebec Fillmore Stevens
Grant Trego Lincoln Freeborn Swift
Gray Wallace Oxford Goodhue Todd
Greeley Washington Penobscot Grant Traverse
Hamilton Wichita Piscataquis Hennepin Wabasha
Haskell Wyandotte Somerset Houston Wadena
Hodgeman KENTUCKY York Hubbard Waseca
Jackson Adair MARYLAND Jackson Washington
Jewell Allen Baltimore Kanabec Watonwan
Johnson Barren Calvert Kandiyohi Wilkin
Kearny Bourbon Carroll Kittson Winona
Kingman Boyle Frederick Lac Qui Parle Wright
Kiowa Bullitt Harford Le Sueur Yellow Medicine
Lane Casey Howard Lincoln MISSOURI
Leavenworth Clark Montgomery Lyon Andrew
Lincoln Cumberland Washington Mahnomen Atchison
Logan Fayette MASS. Marshall Buchanan
Marion Franklin Essex Martin Cass
Marshall Green Middlesex McLeod Clay
McPherson Harrison Worcester Meeker Clinton
Meade Hart MICHIGAN Mower Holt
Mitchell Jefferson Branch Murray Iron
Nemaha Jessamine Calhoun Nicollet Jackson
Ness Lincoln Cass Nobles Nodaway
Norton Marion Hillsdale Norman Platte
Osborne Mercer Jackson Olmsted
Ottawa Metcalfe Kalamazoo Otter Tail

(continued)

APPENDIX AF-4 2022 CALIFORNIA RESIDENTIAL CODE

Copyright © 2022 by, or licensed to, International Code Council, Inc. (ALL RIGHTS RESERVED); licensed to California Building Standards Commission pursuant to License Agreement. No further reproductions is authorized. Any unauthorized reproduction or distribution is a violation of the federal copyright act and the license agreement, and subject to civil and criminal penalties thereunder.

TABLE AF101.1—continued

MONTANA Teton Phelps Taos Transylvania
Beaverhead Toole Pierce NEW YORK Watauga
Big Horn Valley Platte Albany N. DAKOTA
Blaine Wibaux Polk Allegany All Counties
Broadwater Yellowstone Red Willow Broome OHIO
Carbon NEBRASKA Richardson Cattaraugus Adams
Carter Adams Saline Cayuga Allen
Cascade Boone Sarpy Chautauqua Ashland
Chouteau Boyd Saunders Chemung Auglaize
Custer Burt Seward Chenango Belmont
Daniels Butler Stanton Columbia Butler
Dawson Cass Thayer Cortland Carroll
Deer Lodge Cedar Washington Delaware Champaign
Fallon Clay Wayne Dutchess Clark
Fergus Colfax Webster Erie Clinton
Flathead Cuming York Genesee Columbiana
Gallatin Dakota NEVADA Greene Coshocton
Garfield Dixon Carson City Livingston Crawford
Glacier Dodge Douglas Madison Darke
Granite Douglas Eureka Onondaga Delaware
Hill Fillmore Lander Ontario Fairfield
Jefferson Franklin Lincoln Orange Fayette
Judith Basin Frontier Lyon Otsego Franklin
Lake Furnas Mineral Putnam Greene
Lewis and Clark Gage Pershing Rensselaer Guernsey
Madison Gosper White Pine Schoharie Hamilton
McCone Greeley NEW HAMPSHIRE Schuyler Hancock
Meagher Hamilton Carroll Seneca Hardin
Missoula Harlan NEW JERSEY Steuben Harrison
Park Hayes Hunterdon Sullivan Holmes
Phillips Hitchcock Mercer Tioga Huron
Pondera Hurston Monmouth Tompkins Jefferson
Powder River Jefferson Morris Ulster Knox
Powell Johnson Somerset Washington Licking
Prairie Kearney Sussex Wyoming Logan
Ravalli Knox Warren Yates Madison
Richland Lancaster NEW MEXICO N. CAROLINA Marion
Roosevelt Madison Bernalillo Alleghany Mercer
Rosebud Nance Colfax Buncombe Miami
Sanders Nemaha Mora Cherokee Montgomery
Sheridan Nuckolls Rio Arriba Henderson Morrow
Silver Bow Otoe San Miguel Mitchell Muskingum
Stillwater Pawnee Santa Fe Rockingham Perry

(continued)

APPENDIX AF—RADON CONTROL METHODS

Copyright © 2022 by, or licensed to, International Code Council, Inc. (ALL RIGHTS RESERVED); licensed to California Building Standards Commission pursuant to License Agreement. No further reproductions is authorized. Any unauthorized reproduction or distribution is a violation of the federal copyright act and the license agreement, and subject to civil and criminal penalties thereunder.

APPENDIX AF—RADON CONTROL METHODS

TABLE AF101.1—continued

OHIO—continued Lancaster Douglas Hawkins Brunswick
Pickaway Lebanon Edmunds Hickman Buckingham
Pike Lehigh Faulk Humphreys Buena Vista
Preble Luzerne Grant Jackson Campbell
Richland Lycoming Hamlin Jefferson Chesterfield
Ross Mifflin Hand Knox Clarke
Seneca Monroe Hanson Lawrence Clifton Forge
Shelby Montgomery Hughes Lewis Covington
Stark Montour Hutchinson Lincoln Craig
Summit Northampton Hyde Loudon Cumberland
Tuscarawas Northumberland Jerauld Marshall Danville
Union Perry Kingsbury Maury Dinwiddie
Van Wert Schuylkill Lake McMinn Fairfax
Warren Snyder Lincoln Meigs Falls Church
Wayne Sullivan Lyman Monroe Fluvanna
Wyandot Susquehanna Marshall Moore Frederick
PENNSYLVANIA Tioga McCook Perry Fredericksburg
Adams Union McPherson Roane Giles
Allegheny Venango Miner Rutherford Goochland
Armstrong Westmoreland Minnehaha Smith Harrisonburg
Beaver Wyoming Moody Sullivan Henry
Bedford York Perkins Trousdale Highland
Berks RHODE ISLAND Potter Union Lee
Blair Kent Roberts Washington Lexington
Bradford Washington Sanborn Wayne Louisa
Bucks S. CAROLINA Spink Williamson Martinsville
Butler Greenville Stanley Wilson Montgomery
Cameron S. DAKOTA Sully UTAH Nottoway
Carbon Aurora Turner Carbon Orange
Centre Beadle Union Duchesne Page
Chester Bon Homme Walworth Grand Patrick
Clarion Brookings Yankton Piute Pittsylvania
Clearfield Brown TENNESSEE Sanpete Powhatan
Clinton Brule Anderson Sevier Pulaski
Columbia Buffalo Bedford Uintah Radford
Cumberland Campbell Blount VIRGINIA Roanoke
Dauphin Charles Mix Bradley Alleghany Rockbridge
Delaware Clark Claiborne Amelia Rockingham
Franklin Clay Davidson Appomattox Russell
Fulton Codington Giles Augusta Salem
Huntingdon Corson Grainger Bath Scott
Indiana Davison Greene Bland Shenandoah
Juniata Day Hamblen Botetourt Smyth
Lackawanna Deuel Hancock Bristol Spotsylvania

(continued)

APPENDIX AF-6 2022 CALIFORNIA RESIDENTIAL CODE

Copyright © 2022 by, or licensed to, International Code Council, Inc. (ALL RIGHTS RESERVED); licensed to California Building Standards Commission pursuant to License Agreement. No further reproductions is authorized. Any unauthorized reproduction or distribution is a violation of the federal copyright act and the license agreement, and subject to civil and criminal penalties thereunder.

APPENDIX AF—RADON CONTROL METHODS

TABLE AF101.1—continued

VIRGINIA—continued Brooke WISCONSIN Richland Hot Springs
Stafford Grant Buffalo Rock Johnson
Staunton Greenbrier Crawford Shawano Laramie
Tazewell Hampshire Dane St. Croix Lincoln
Warren Hancock Dodge Vernon Natrona
Washington Hardy Door Walworth Niobrara
Waynesboro Jefferson Fond du Lac Washington Park
Winchester Marshall Grant Waukesha Sheridan
Wythe Mercer Green Waupaca Sublette
WASHINGTON Mineral Green Lake Wood Sweetwater
Clark Monongalia Iowa WYOMING Teton
Ferry Monroe Jefferson Albany Uinta
Okanogan Morgan Lafayette Big Horn Washakie
Pend Oreille Ohio Langlade Campbell
Skamania Pendleton Marathon Carbon
Spokane Pocahontas Menominee Converse
Stevens Preston Pepin Crook
W. VIRGINIA Summers Pierce Fremont
Berkeley Wetzel Portage Goshen

a. The EPA recommends that this county listing be supplemented with other available state and local data to further understand the radon potential of a Zone 1

area.

Copyright © 2022 by, or licensed to, International Code Council, Inc. (ALL RIGHTS RESERVED); licensed to California Building Standards Commission pursuant to License Agreement. No further reproductions is authorized. Any unauthorized reproduction or distribution is a violation of the federal copyright act and the license agreement, and subject to civil and criminal penalties thereunder.

APPENDIX AF—RADON CONTROL METHODS

TYPICAL SUBSLAB DEPRESSURIZATION

PASSIVE RADON SYSTEM

PASSIVE RADON SYSTEM VENTED

THROUGH SUMP

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▸Contents — California Residential Code (Title 24, Part 2.5)
California Residential Code (Title 24, Part 2.5)
  1. Chapter 2 — DEFINITIONS AND ABBREVIATIONS
  2. Appendix AF — RADON CONTROL
  3. Appendix AI — PRIVATE SEWAGE
  4. Appendix AJ — EXISTING
  5. Appendix AK — SOUND
  6. Appendix AO — AUTOMATIC
  7. Appendix AR — LIGHT STRAW-CLAY
  8. Appendix AS — STRAWBALE
  9. Appendix AU — COB CONSTRUCTION
  10. Appendix AV — BOARD
  11. Appendix AW — 3D-PRINTED BUILDING
  12. Chapter 1 — SCOPE AND APPLICATION
  13. Chapter 3 — BUILDING PLANNING
  14. Chapter 4 — FOUNDATIONS
  15. Chapter 5 — FLOORS
  16. Chapter 6 — WALL CONSTRUCTION
  17. Chapter 7 — WALL COVERING
  18. Chapter 8 — ROOF-CEILING CONSTRUCTION
  19. Chapter 9 — ROOF ASSEMBLIES
  20. Chapter 10 — CHIMNEYS AND FIREPLACES
  21. ▸Chapter 44 — REFERENCED STANDARDS
    Overview
    1. Section AF101
    2. Section AF102
    3. Section AF103
    4. Section AF104
  22. Appendix AH — PATIO COVERS
  23. Appendix AL — PERMIT FEES
  24. Appendix AQ — TINY HOUSES
  25. Appendix AT — SOLAR-READY PROVISIONS—DETACHED ONE- AND
  26. Appendix AX — SWIMMING POOL SAFETY ACT
  27. Appendix AY — AREAS PROTECTED BY THE FACILITIES
  28. Appendix AZ — EMERGENCY HOUSING

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