APPENDIX B
RADON MITIGATION


  • SECTION B101
    GENERAL

    B101.1 Radon mitigation.
    Buildings in areas of High and Moderate Radon Potential (Zone 1 and 2), as determined by Figure B101.1 and Table B101.1 shall comply with Sections B201.1 through B201.10.

    FIGURE B101.1
    EPA MAP OF RADON ZONES

    a. pCi/L standard for picocuries per liter of radon gas. EPA recommends that all homes that measure 4 pCi/L and greater be mitigated
    The United States Environmental Protection Agency and the United States Geological Survey have evaluated the radon potential in the United States and have developed a map of radon zones designed to assist code officials in deciding whether radon-resistant features are applicable in new construction.
    The map assigns each of the 3,141 counties in the United States to one of three zones based on radon potential. Each zone designation reflects the average short-term radon measurement result that can be expected to be measured in a building without the implementation of radon control methods. The radon zone designation of highest priority is Zone 1 and Zone 2. Table 804.2 lists the Zone 1 counties illustrated on the map. The counties are listed by state and alphabetically within each zone. More detailed information can be obtained from state-specific booklets (EPA-402-R-93-021 through 070) available through the U.S. EPA National Service Center for Environmental Publications (NSCEP), U.S. EPA Regional Offices or State Radon Offices.

    TABLE B101.1
    EPA RADON ZONE 1 and 2 COUNTIES BY STATEa

    ALABAMAALASKAZone 2GilpinNew Haven
    Zone 1Zone 2AlamedaGrandNew London
    CalhounAnchorage MunicipalityAlpineGunnison
    ClayDillingham Census AreaAmadorHuerfanoZone 2
    CleburneFairbanks North StarCalaverasJacksonLitchfield
    ColbertBoroughContra CostaJeffersonTolland
    CoosaKenai PeninsulaEl DoradoKiowaWindham
    FranklinBoroughFresnoKit Carson
    JacksonMatanuska-SusitnaInyoLa PlataDELAWARE
    LauderdaleBoroughKernLarimerZone 2
    LawrenceSoutheast FairbanksLos AngelesLas AnimasNew Castle
    LimestoneCensus AreaMaderaLincoln
    MadisonMariposaLoganFLORIDA
    MorganARIZONAMonoMesaZone 2
    TalladegaZone 2MontereyMoffatAlachua
    ApacheNevadaMontezumaCitrus
    Zone 2CochisePlacerMontroseColumbia
    AutaugaCoconinoPlumasMorganHillsborough
    BarbourGilaRiversideOteroLeon
    BibbGrahamSan BenitoOurayMarion
    BlountGreenleeSan BernardinoParkMiami-Dade
    BullockLa PazSan FranciscoPhillipsPolk
    CherokeeMaricopaSan Luis ObispoPitkinUnion
    ChiltonMohaveSan MateoProwers
    CullmanNavajoSanta ClaraPuebloGEORGIA
    DallasPimaSanta CruzRio BlancoZone 1
    DeKalbPinalSierraSan MiguelCobb
    ElmoreSanta CruzTulareSedgwickDeKalb
    EtowahYavapaiTuolumneSummitFulton
    FayetteYumaYubaTellerGwinnett
    GreeneWashington
    HaleARKANSASCOLORADOWeldZone 2
    JeffersonZone 2Zone 1YumaBanks
    LamarBaxterAdamsBarrow
    LeeBentonArapahoeZone 2Bartow
    LowndesBooneBacaAlamosaButts
    MaconCarrollBentArchuletaCarroll
    MarionFultonBoulderConejosCatoosa
    MarshallGarlandBroomfieldCostillaCherokee
    MontgomeryIndependenceChaffeeEagleClarke
    PerryIzardCheyenneHinsdaleClayton
    PickensMarionClear CreekLakeCoweta
    RandolphMontgomeryCrowleyMineralDawson
    RussellRandolphCusterRio GrandeDouglas
    ShelbySearcyDeltaRouttElbert
    St ClairSharpDenverSaguacheFannin
    SumterStoneDoloresSan JuanFayette
    TuscaloosaDouglasFloyd
    WalkerCALIFORNIAEl PasoCONNECTICUTForsyth
    WinstonZone 1ElbertZone 1Franklin
    Santa BarbaraFremontFairfieldGilmer
    VenturaGarfieldMiddlesexGreene

    (continued)

    TABLE B101.1—continued
    EPA RADON ZONE 1 and 2 COUNTIES BY STATEa

    HabershamIdahoJerseyHardinHendricks
    HallKootenaiJo DaviessJacksonHenry
    HaralsonLatahKaneJasperHoward
    HarrisLemhiKendallJeffersonHuntington
    HartShoshoneKnoxJohnsonJay
    HeardValleyLaSalleKankakeeJennings
    HenryLeeLakeJohnson
    JacksonZone 2LivingstonLawrenceKosciusko
    JasperAdaLoganMacoupinLaGrange
    LamarBannockMaconMadisonLawrence
    LumpkinBear LakeMarshallMarionMadison
    MadisonBinghamMasonMcHenryMarion
    MeriwetherBonnevilleMcDonoughMonroeMarshall
    MonroeCanyonMcLeanMontgomeryMiami
    MorganCaribouMenardPerryMonroe
    NewtonCassiaMercerPopeMontgomery
    OconeeFranklinMorganRandolphNoble
    OglethorpeJeffersonMoultrieRichlandOrange
    PauldingJeromeOgleSalinePutnam
    PickensLincolnPeoriaShelbyRandolph
    PikeMadisonPiattSt ClairRush
    RabunMinidokaPikeUnionScott
    RichmondOneidaPutnamWabashShelby
    RockdaleOwyheeRock IslandWashingtonSt Joseph
    SpaldingPayetteSangamonWayneSteuben
    StephensPowerSchuylerWhiteTippecanoe
    TalbotTetonScottWillTipton
    TownsTwin FallsStarkWilliamsonUnion
    TroupStephensonVermillion
    UnionILLINOISTazewellINDIANAWabash
    UpsonZone 1VermilionZone 1Warren
    WalkerAdamsWarrenAdamsWashington
    WaltonBooneWhitesideAllenWayne
    WhiteBrownWinnebagoBartholomewWells
    WhitfieldBureauWoodfordBentonWhite
    CalhounBlackfordWhitley
    IDAHOCarrollZone 2Boone
    Zone 1CassBondCarrollZone 2
    BenewahChampaignChristianCassBrown
    BlaineColesClarkClarkClay
    BoiseDe KalbClayClintonCrawford
    BonnerDe WittClintonDe KalbDaviess
    BoundaryDouglasCookDecaturDearborn
    ButteEdgarCrawfordDelawareDubois
    CamasFordCumberlandElkhartFloyd
    ClarkFultonDuPageFayetteFranklin
    ClearwaterGreeneEdwardsFountainGibson
    CusterGrundyEffinghamFultonGreene
    ElmoreHancockFayetteGrantJackson
    FremontHendersonFranklinHamiltonJasper
    GoodingHenryGallatinHancockJefferson
    IroquoisHamiltonHarrisonKnox

    (continued)

    TABLE B101.1—continued
    EPA RADON ZONE 1 and 2 COUNTIES BY STATEa

    LakeDes MoinesSacLincolnElk
    LaPorteDickinsonScottLoganFranklin
    MartinDubuqueShelbyMarionGreenwood
    MorganEmmetSiouxMarshallHarper
    NewtonFayetteStoryMcPhersonHarvey
    OhioFloydTamaMeadeJefferson
    OwenFranklinTaylorMitchellLabette
    ParkeFremontUnionNemahaLinn
    PerryGreeneVan BurenNessLyon
    PikeGrundyWapelloNortonMiami
    PorterGuthrieWarrenOsborneMontgomery
    PoseyHamiltonWashingtonOttawaMorris
    PulaskiHancockWaynePawneeMorton
    RipleyHardinWebsterPhillipsNeosho
    SpencerHarrisonWinnebagoPottawatomieOsage
    StarkeHenryWinneshiekPrattReno
    SullivanHowardWoodburyRawlinsSedgwick
    SwitzerlandHumboldtWorthRepublicSeward
    VanderburghIdaWrightRiceShawnee
    VigoIowaRileyStafford
    WarrickJacksonKANSASRooksStevens
    JasperZone 1RushSumner
    IOWAJeffersonAtchisonRussellWabaunsee
    Zone 1JohnsonBartonSalineWilson
    AdairJonesBrownScottWoodson
    AdamsKeokukCheyenneSheridan
    AllamakeeKossuthClayShermanKENTUCKY
    AppanooseLeeCloudSmithZone 1
    AudubonLinnDecaturStantonAdair
    BentonLouisaDickinsonThomasAllen
    Black HawkLucasDouglasTregoBarren
    BooneLyonEllisWallaceBourbon
    BremerMadisonEllsworthWashingtonBoyle
    BuchananMahaskaFinneyWichitaBullitt
    Buena VistaMarionFordWyandotteCasey
    ButlerMarshallGearyClark
    CalhounMillsGoveZone 2Cumberland
    CarrollMitchellGrahamAllenFayette
    CassMononaGrantAndersonFranklin
    CedarMonroeGrayBarberGreen
    Cerro GordoMontgomeryGreeleyBourbonHarrison
    CherokeeMuscatineHamiltonButlerHart
    ChickasawO′BrienHaskellChaseJefferson
    ClarkeOsceolaHodgemanChautauquaJessamine
    ClayPageJacksonCherokeeLincoln
    ClaytonPalo AltoJewellClarkMarion
    ClintonPlymouthJohnsonCoffeyMercer
    CrawfordPocahontasKearnyComancheMetcalfe
    DallasPolkKingmanCowleyMonroe
    DavisPottawattamieKiowaCrawfordNelson
    DecaturPoweshiekLaneDoniphanPendleton
    DelawareRinggoldLeavenworthEdwardsPulaski

    (continued)

    TABLE B101.1—continued
    EPA RADON ZONE 1 and 2 COUNTIES BY STATEa

    RobertsonLetcherYorkJacksonDouglas
    RussellLewisZone 2KalamazooFaribault Count
    ScottLivingstonKnoxLenaweeFillmore
    TaylorLoganSagadahocSt JosephFreeborn
    WarrenLyonWaldoWashtenawGoodhue
    WoodfordMadisonWashingtonGrant
    MagoffinZone 2Hennepin
    Zone 2MartinMARYLANDAlconaHouston
    AndersonMasonZone 1AlgerHubbard
    BathMcCrearyBaltimoreAlpenaJackson
    BellMcLeanCalvertAntrimKanabec
    BooneMeadeCarrollBaragaKandiyohi
    BoydMenifeeFrederickBarryKittson
    BrackenMontgomeryHarfordCharlevoixLac qui Parle
    BreathittMorganHowardClintonLe Sueur
    BreckinridgeMuhlenbergMontgomeryDickinsonLincoln
    ButlerNicholasWashingtonEatonLyon
    CaldwellOhioEmmetMahnomen
    CampbellOldhamZone 2GeneseeMarshall
    CarrollOwenAlleganyGogebicMartin
    CarterOwsleyAnne ArundelHoughtonMcLeod
    ChristianPerryBaltimore CityInghamMeeker
    ClayPikeCecilIoniaMower
    ClintonPowellCharlesIronMurray
    CrittendenRockcastleGarrettKentNicollet
    DaviessRowanPrince George′sKeweenawNobles
    EdmonsonShelbySomersetLapeerNorman
    ElliottSimpsonLeelanauOlmsted
    EstillSpencerMASSACHUSETTSLivingstonOtter Tail
    FlemingToddZone 1MarquettePennington
    FloydTriggEssexMenomineePipestone
    GallatinTrimbleMiddlesexMonroePolk
    GarrardUnionWorcesterMontcalmPope
    GrantWashingtonMontmorencyRamsey
    GraysonWayneZone 2OaklandRed Lake
    GreenupWebsterBarnstableOtsegoRedwood
    HancockWhitleyBerkshirePresque IsleRenville
    HardinWolfeBristolSanilacRice
    HarlanDukesShiawasseeRock
    HendersonMAINEFranklinRoseau
    HenryZone 1HampdenMINNESOTAScott
    HopkinsAndroscogginHampshireZone 1Sherburne
    JacksonAroostookNantucketBeckerSibley
    JohnsonCumberlandNorfolkBig StoneStearns
    KentonFranklinPlymouthBlue EarthSteele
    KnottHancockBrownStevens
    KnoxKennebecMICHIGANCarverSwift
    LarueLincolnZone 1ChippewaTodd
    LaurelOxfordBranchClayTraverse
    LawrencePenobscotCalhounCottonwoodWabasha
    LeePiscataquisCassDakotaWadena
    LeslieSomersetHillsdaleDodgeWaseca

    (continued)

    TABLE B101.1—continued
    EPA RADON ZONE 1 and 2 COUNTIES BY STATEa

    WashingtonNodawayMaconBeaverheadMusselshell
    WatonwanPlatteMadisonBig HornPetroleum
    WilkinMariesBlaineSweet Grass
    WinonaZone 2MarionBroadwaterTreasure
    WrightAdairMcDonaldCarbonWheatland
    Yellow MedicineAudrainMercerCarterYellowstone
    BarryMillerCascade
    Zone 2BartonMoniteauChouteauNEBRASKA
    AitkinBatesMonroeCusterZone 1
    AnokaBentonMontgomeryDanielsAdams
    BeltramiBollingerMorganDawsonBoone
    BentonBooneNewtonDeer LodgeBoyd
    CarltonCaldwellOregonFallonBurt
    CassCallawayOsageFergusButler
    ChisagoCamdenOzarkFlatheadCass
    ClearwaterCape GirardeauPerryGallatinCedar
    CookCarrollPettisGarfieldClay
    Crow WingCarterPhelpsGlacierColfax
    IsantiCedarPikeGraniteCuming
    ItascaCharitonPolkHillDakota
    KoochichingChristianPulaskiJeffersonDixon
    LakeClarkPutnamJudith BasinDodge
    Lake of the WoodsColeRallsLakeDouglas
    Mille LacsCooperRandolphLewis and ClarkFillmore
    MorrisonCrawfordRayLibertyFranklin
    PineDadeReynoldsLincolnFrontier
    St LouisDallasRipleyMadisonFurnas
    DaviessSalineMcConeGage
    MISSISSIPPIDeKalbSchuylerMeagherGosper
    Zone 2DentScotlandMineralGreeley
    AlcornDouglasShannonMissoulaHamilton
    ChickasawFranklinShelbyParkHarlan
    ClayGasconadeSt CharlesPhillipsHayes
    LeeGentrySt ClairPonderaHitchcock
    LowndesGreeneSt FrancoisPowder RiverJefferson
    NoxubeeGrundySt Louis cityPowellJohnson
    PontotocHarrisonSt LouisPrairieKearney
    RankinHenrySte GenevieveRavalliKnox
    UnionHickoryStoneRichlandLancaster
    WashingtonHowardSullivanRooseveltMadison
    HowellTaneyRosebudNance
    MISSOURIJasperTexasSandersNemaha
    Zone 1JeffersonVernonSheridanNuckolls
    AndrewJohnsonWarrenSilver BowOtoe
    AtchisonKnoxWashingtonStillwaterPawnee
    BuchananLacledeWayneTetonPhelps
    CassLafayetteWebsterToolePierce
    ClayLawrenceWorthValleyPlatte
    ClintonLewisWrightWibauxPolk
    HoltLincolnRed Willow
    IronLinnMONTANAZone 2Richardson
    JacksonLivingstonZone 1Golden ValleySaline

    (continued)

    TABLE B101.1—continued
    EPA RADON ZONE 1 and 2 COUNTIES BY STATEa

    SarpyEsmeraldaTaosPutnamGaston
    SaundersHumboldtZone 2RensselaerGraham
    SewardNyeCatronSchoharieHaywood
    StantonStoreyChavesSchuylerIredell
    ThayerWashoeCibolaSenecaJackson
    ThurstonCurrySteubenLincoln
    WashingtonNEW HAMPSHIREDe BacaSullivanMacon
    WayneZone 1Dona AnaTiogaMadison
    WebsterCarrollEddyTompkinsMcDowell
    YorkGrantUlsterPolk
    Zone 2GuadalupeWashingtonRutherford
    Zone 2BelknapHardingWyomingStokes
    AntelopeCheshireHidalgoYatesSurry
    BannerCoosLeaSwain
    Box ButteGraftonLincolnZone 2Vance
    BuffaloHillsboroughLos AlamosClintonWake
    ChaseMerrimackLunaJeffersonWarren
    CheyenneRockinghamMcKinleyLewisWilkes
    CusterStraffordOteroMonroeYadkin
    DawesSullivanQuayMontgomeryYancey
    DawsonRooseveltNiagara
    DeuelNEW JERSEYSan JuanOneidaNORTH DAKOTA
    DundyZone 1SandovalOrleansZone 1
    HallHunterdonSierraOswegoAdams
    HowardMercerSocorroSaratogaBarnes
    KeithMonmouthTorranceSchenectadyBenson
    Keya PahaMorrisUnionSt LawrenceBillings
    KimballSomersetValenciaWayneBottineau
    MerrickSussexBowman
    MorrillWarrenNEW YORKNORTH CAROLINABurke
    PerkinsZone 1Zone 1Burleigh
    Scotts BluffZone 2AlbanyAlleghanyCass
    SheridanBergenAlleganyBuncombeCavalier
    ShermanBurlingtonBroomeCherokeeDickey
    SiouxCamdenCattaraugusHendersonDivide
    ValleyCumberlandCayugaMitchellDunn
    EssexChautauquaRockinghamEddy
    NEVADAGloucesterChemungTransylvaniaEmmons
    Zone 1HudsonChenangoWataugaFoster
    Carson CityMiddlesexColumbiaGolden Valley
    DouglasPassaicCortlandZone 2Grand Forks
    EurekaSalemDelawareAlexanderGrant
    LanderUnionDutchessAsheGriggs
    LincolnErieAveryHettinger
    LyonNEW MEXICOGeneseeBurkeKidder
    MineralZone 1GreeneCaldwellLaMoure
    PershingBernalilloLivingstonCaswellLogan
    White PineColfaxMadisonCatawbaMcHenry
    MoraOnondagaClayMcIntosh
    Zone 2Rio ArribaOntarioClevelandMcKenzie
    ChurchillSan MiguelOrangeForsythMcLean
    ElkoSanta FeOtsegoFranklinMercer

    (continued)

    TABLE B101.1—continued
    EPA RADON ZONE 1 and 2 COUNTIES BY STATEa

    MortonHuronMorganAdamsCrawford
    MountrailJeffersonNobleAlleghenyElk
    NelsonKnoxOttawaArmstrongErie
    OliverLickingPauldingBeaverFayette
    PembinaLoganPortageBedfordForest
    PierceMadisonPutnamBerksGreene
    RamseyMarionSanduskyBlairJefferson
    RansomMercerSciotoBradfordLawrence
    RenvilleMiamiTrumbullBucksMcKean
    RichlandMontgomeryVintonButlerMercer
    RoletteMorrowWashingtonCameronPike
    SargentMuskingumWilliamsCarbonPotter
    SheridanPerryWoodCentreSomerset
    SiouxPickawayChesterWarren
    SlopePikeOKLAHOMAClarionWashington
    StarkPrebleZone 2ClearfieldWayne
    SteeleRichlandAdairClinton
    StutsmanRossBeaverColumbiaRHODE ISLAND
    TownerSenecaCherokeeCumberlandZone 1
    TraillShelbyCimarronDauphinKent
    WalshStarkDelawareDelawareWashington
    WardSummitEllisFranklin
    WellsTuscarawasMayesFultonZone 2
    WilliamsUnionSequoyahHuntingdonNewport
    Van WertTexasIndianaProvidence
    OHIOWarrenJuniata
    Zone 1WayneOREGONLackawannaSOUTH CAROLINA
    AdamsWyandotZone 2LancasterZone 1
    AllenBakerLebanonGreenville
    AshlandZone 2ClatsopLehigh
    AuglaizeAshtabulaColumbiaLuzerneZone 2
    BelmontAthensCrookLycomingAbbeville
    ButlerBrownGilliamMifflinAnderson
    CarrollClermontGrantMonroeCherokee
    ChampaignCuyahogaHarneyMontgomeryLaurens
    ClarkDefianceHood RiverMontourOconee
    ClintonErieJeffersonNorthamptonPickens
    ColumbianaFultonKlamathNorthumberlandSpartanburg
    CoshoctonGalliaLakePerryYork
    CrawfordGeaugaMalheurSchuylkill
    DarkeHenryMorrowSnyderSOUTH DAKOTA
    DelawareHighlandMultnomahSullivanZone 1
    FairfieldHockingShermanSusquehannaAurora
    FayetteJacksonUmatillaTiogaBeadle
    FranklinLakeUnionUnionBon Homme
    GreeneLawrenceWascoVenangoBrookings
    GuernseyLorainWashingtonWestmorelandBrown
    HamiltonLucasWheelerWyomingBrule
    HancockMahoningYamhillYorkBuffalo
    HardinMedinaCampbell
    HarrisonMeigsPENNSYLVANIAZone 2Charles Mix
    HolmesMonroeZone 1CambriaClark

    (continued)

    TABLE B101.1—continued
    EPA RADON ZONE 1 and 2 COUNTIES BY STATEa

    ClayMelletteCarterHutchinsonWayne
    CodingtonPenningtonCheathamJeff DavisWeber
    CorsonShannonChesterLamb
    DavisonToddClayLipscombVERMONT
    DayTrippCockeLlanoZone 2
    DeuelZiebachCoffeeLubbockAddison
    DouglasDecaturLynnBennington
    EdmundsTENNESSEEDeKalbMasonCaledonia
    FaulkZone 1DicksonMooreEssex
    GrantAndersonFentressOchiltreeFranklin
    HamlinBedfordHamiltonOldhamLamoille
    HandBlountHardinParmerOrange
    HansonBradleyHendersonPotterOrleans
    HughesClaiborneHoustonPresidioRutland
    HutchinsonDavidsonJohnsonRandallWashington
    HydeGilesMarionReevesWindham
    JerauldGraingerMcNairyRobertsWindsor
    KingsburyGreeneMontgomerySherman
    LakeHamblenOvertonSwisherVIRGINIA
    LincolnHancockPickettTerrellZone 1
    LymanHawkinsPolkAlleghany
    MarshallHickmanPutnamUTAHAmelia
    McCookHumphreysRobertsonZone 1Appomattox
    McPhersonJacksonSevierCarbonAugusta
    MinerJeffersonStewartDuchesneBath
    MinnehahaKnoxSumnerGrandBland
    MoodyLawrenceUnicoiPiuteBotetourt
    PerkinsLewisVan BurenSanpeteBrunswick
    PotterLincolnWarrenSevierBuckingham
    RobertsLoudonWhiteUintahCampbell
    SanbornMaconChesterfield
    SpinkMadisonTEXASZone 2Clarke
    StanleyMarshallZone 2BeaverCraig
    SullyMcMinnArmstrongBox ElderCumberland
    TurnerMeigsBaileyCacheDinwiddie
    UnionMonroeBrewsterDaggettFairfax
    WalworthMooreCarsonDavisFluvanna
    YanktonPerryCastroEmeryFrederick
    RoaneCrosbyGarfieldGiles
    Zone 2RutherfordCulbersonIronGoochland
    BennettSmithDallamJuabHenry
    ButteSullivanDeaf SmithKaneHighland
    CusterTrousdaleDonleyMillardLee
    DeweyUnionFloydMorganLouisa
    Fall RiverWashingtonGarzaRichMontgomery
    GregoryWayneGraySalt LakeNottoway
    HaakonWilliamsonHaleSan JuanOrange
    HardingWilsonHansfordSummitPage
    JacksonHartleyTooelePatrick
    JonesZone 2HemphillUtahPittsylvania
    LawrenceBentonHockleyWasatchPowhatan
    MeadeCannonHudspethWashingtonPulaski

    (continued)

    TABLE B101.1—continued
    EPA RADON ZONE 1 and 2 COUNTIES BY STATEa

    RoanokePend OreilleBarbourMarathonOneida
    RockbridgeSkamaniaBraxtonMenomineeOutagamie
    RockinghamSpokaneCabellPepinOzaukee
    RussellStevensCalhounPiercePolk
    ScottClayPortagePrice
    ShenandoahZone 2DoddridgeRichlandRacine
    SmythAdamsFayetteRockRusk
    SpotsylvaniaAsotinGilmerShawanoSauk
    StaffordBentonHarrisonSt CroixSawyer
    TazewellColumbiaJacksonVernonSheboygan
    WarrenDouglasLewisWalworthTaylor
    WashingtonFranklinLincolnWashingtonTrempealeau
    WytheGarfieldMarionWaukeshaVilas
    GrantMasonWaupacaWashburn
    Zone 2KittitasNicholasWoodWaushara
    AlbemarleKlickitatPleasantsWinnebago
    AmherstLincolnPutnamZone 2
    ArlingtonWalla WallaRaleighAdamsWYOMING
    BedfordWhitmanRandolphAshlandZone 1
    BuchananYakimaRitchieBarronAlbany
    CarrollRoaneBayfieldBig Horn
    CharlotteWEST VIRGINIATaylorBrownCampbell
    CulpeperZone 1TuckerBurnettCarbon
    DickensonBerkeleyTylerCalumetConverse
    FauquierBrookeUpshurChippewaCrook
    FloydGrantWayneClarkFremont
    FranklinGreenbrierWebsterColumbiaGoshen
    GraysonHampshireWirtDouglasHot Springs
    GreeneHancockWoodDunnJohnson
    HalifaxHardyEau ClaireLaramie
    LoudounJeffersonWISCONSINFlorenceLincoln
    LunenburgMarshallZone 1ForestNatrona
    MadisonMercerBuffaloIronNiobrara
    MecklenburgMineralCrawfordJacksonPark
    NelsonMonongaliaDaneJuneauSheridan
    Prince EdwardMonroeDodgeKenoshaSublette
    Prince WilliamMorganDoorKewauneeSweetwater
    RappahannockOhioFond du LacLa CrosseTeton
    WisePendletonGrantLincolnUinta
    PocahontasGreenManitowocWashakie
    WASHINGTONPrestonGreen LakeMarinette
    Zone 1SummersIowaMarquetteZone 2
    ClarkWetzelJeffersonMilwaukeePlatte
    FerryLafayetteMonroeWeston
    OkanoganZone 2LangladeOconto

    SECTION B102
    DEFINITIONS

    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 found in soil that is not detectable by human senses.

    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.

    SECTION B201
    MITIGATION PROCEDURES

    B201.1 Subfloor preparation.
    A layer of gas-permeable material shall be placed under all concrete slabs and other floor systems that directly contact the ground and that are within the walls of the occupied spaces of the building, as a prerequisite for passive and active subslab depressurization systems. The gas-permeable layer shall consist of one of the following:

    1. A uniform layer of clean aggregate, not less than 4 inches (102 mm) in thickness. The aggregate shall consist of material that will pass through a 2-inch (51 mm) sieve and be retained by a 1/2-inch (12.7mm) sieve. Size 5, 56 or 6 aggregate shall be used and shall meet the specifications of ASTM C 33. Where compaction is required or practiced, a geotextile fabric or reinforced vapor retarder shall be used beneath the aggregate to prevent fines and soil from being introduced into the aggregate.

    2. A uniform layer of sand (native or fill), not less than 4 inches (102 mm) in thickness, overlain by a layer or strips of geotextile drainage matting designed to allow the lateral flow of soil gases.

    3. Geotextile drainage matting, or other materials, systems or floor designs with demonstrated capability to permit depressurization across the entire subfloor area.

    B201.2 Subslab radon suction pit.
    A radon suction pit without aggregate shall be installed in the center of each 100,000 square feet (9390 m2) of floor area that is in contact with the earth and that has no subslab barriers. The suction pit void area shall be not less than 4 square feet (0.371 m2) and the pit shall be not less than 8 inches (203 mm) in depth. The resulting suction pit void to aggregate interface shall be 7 square feet (0.65 m2), or 30 times the cross sectional area of a 6-inch (157.4 mm) radon vent pipe. Alternatively, a concrete drainage distribution box or similar structure meeting the 30:1 ratio shall be employed. The suction pit shall be covered with 3/4-inch-thick (19.05 mm) pressure-treated plywood or an equivalent material prior to pouring the slab. The section of slab covering the suction pit shall be reinforced.

    B201.3 Radon vent piping.
    Radon vent piping shall be not less than 6 inches (157.4 mm) in diameter and constructed of PVC or equivalent gas-tight pipe.

    B201.3.1 Subslab suction pit horizontal vent pipe.
    A section of vent pipe not less than of 5 feet (1.52 m) in length shall be placed in the aggregate and shall enter the suction pit horizontally. One end of the vent pipe shall be placed so as to terminate midway in the suction pit. The vent pipe shall be supported at the boundary of the aggregate-void space so as to maintain its position. The horizontal pipe run shall provide positive condensation drainage to the suction pit with a pitch of not less than 1/8 inch per foot (13 mm per meter).

    B201.3.2 Subslab suction pit vertical vent pipe.
    A 90-degree (1.57 rad) elbow shall be installed on the end of the vent pipe in the aggregate. A section of vent pipe shall be connected to the elbow and shall pass vertically through and above the slab to a height of not less than 2 feet (610 mm), and shall be covered with a temporary cap. A pipe sleeve or coupling extending through the full depth of the slab shall be used to protect the vent pipe where it passes through the slab, and the slab penetration shall be sealed in accordance with Section B201.5.

    B201.4 Soil-gas-retarder.
    A minimum 6-mil (0.15 mm) [or 3-mil (0.075 mm) cross-laminated] polyethylene or equivalent flexible sheeting material that conforms to ASTM E 1643 shall be placed on top of the gas-permeable layer prior to casting the slab or placing the floor assembly to serve as a soil-gas-retarder by bridging any cracks that develop in the slab or floor assembly and to prevent concrete from entering the void spaces in the aggregate base material. The sheeting shall cover the entire floor area with separate sections of sheeting lapped at least 12 inches (305 mm). The sheeting shall fit closely around any pipe, wire or other penetrations of the material. All punctures or tears in the material shall be sealed or covered with additional sheeting having an overlap of not less than 12 inches (305 mm) on all sides.

    B201.5 Entry routes.
    Potential radon entry routes shall be sealed or closed in accordance with Sections B201.5.1 through B201.5.10.

    B201.5.1 Floor openings.
    Piping and other penetrations through concrete slabs or other floor assemblies shall be filled or sealed with a polyurethane caulk or equivalent sealant that complies with ASTM C 920 Class 25 or greater and is applied in accordance with the manufacturer's recommendations. Prior to sealing, backer rods shall be used to fill gaps greater than 1/2 inch (12.7 mm).

    B201.5.2 Concrete joints.
    Slab joints, control saw joints, isolation joints, construction joints, pour joints, floor and wall intersection joints, and any other joints in concrete slabs or between slabs and foundation walls shall be sealed with a caulk or sealant. Gaps and joints shall be cleared of loose material and filled with a polyurethane caulk or other elastomeric sealant that complies with ASTM C 920 Class 25 or greater and is applied in accordance with the manufacturer's recommendations. Prior to sealing, backer rods shall be used to fill gaps that are greater than 1/2 inch (12.7 mm) in depth.

    B201.5.3 Drains.
    Where floor, condensate and other drains discharge to the soil and not a sewer, such drains shall be provided with a water-seal trap or shall be water trapped or routed through nonperforated pipe to a point above grade.

    B201.5.4 Sumps.
    Sump pits open to soil or serving as the termination point for subslab or exterior drain tile loops shall be covered with a gasketed or otherwise sealed lid. Sumps used as a floor drain shall have a lid equipped with a trapped inlet.

    B201.5.5 Foundation walls.
    Hollow block masonry foundation walls shall be constructed with either a continuous course of solid masonry, one course of masonry grouted solid, or a solid concrete beam at or above finished ground surface to prevent passage of air from the interior of the wall into the living space. Where a brick veneer or other masonry ledge is installed, the course immediately below that ledge shall be sealed. Joints, cracks and other openings around all penetrations of both exterior and interior surfaces of masonry block or wood foundation walls below the ground surface shall be filled with a polyurethane caulk or other equivalent sealant that complies with ASTM C 920 Class 25 or greater and is applied in accordance with the manufacturer's recommendations. Penetrations of concrete walls shall be filled.

    B201.5.6 Dampproofing.
    The exterior surfaces of portions of concrete and masonry block walls below the ground surface shall be dampproofed.

    B201.5.7 Air-handling units.
    Air-handling units in crawl spaces shall be sealed to prevent air from being drawn into the unit.

    Exception: Units with gasketed seams or units that are otherwise sealed by the manufacturer to prevent leakage.

    B201.5.8 Ducts.
    Ductwork for supply or return air shall not be located in crawl spaces or beneath a slab in areas with high or moderate radon potential. Where ductwork passes through or beneath a slab, it shall be of seamless material or sealed water tight. Joints in such ductwork shall be sealed water tight.

    B201.5.9 Crawl space floors.
    Openings around all penetrations through floors above crawl spaces shall be caulked or otherwise filled to prevent air leakage.

    B201.5.10 Crawl space access.
    Access doors and other openings or penetrations between basements and adjoining crawl spaces shall be closed, gasketed or otherwise filled to prevent air leakage.

    B201.6 Passive submembrane depressurization system.
    In buildings with crawl space foundations, the following components of a passive submembrane depressurization system shall be installed during construction.

    Exception: Buildings in which an approved mechanical crawl space ventilation system or other equivalent system is installed.

    B201.6.1 Ventilation.
    Crawl spaces shall be provided with vents to the exterior of the building.

    B201.6.2 Soil-gas-retarder.
    The soil in crawl spaces shall be covered with a continuous layer of minimum 6-mil (0.15 mm) polyethylene soil-gas-retarder that conforms to ASTM E 1643. The ground cover shall be lapped a minimum of 12 inches (305 mm) at joints and shall extend to all foundation walls enclosing the crawl space area.

    B201.6.3 Vent pipe.
    A plumbing tee or other approved connection shall be inserted horizontally beneath the sheeting and connected to a 3- or 4-inch-diameter (76 mm or 102 mm) fitting with a vertical vent pipe installed through the sheeting. The vent pipe shall be extended up through the building floors, terminate at least 12 inches (305 mm) above the roof in a location at least 10 feet (3048 mm) away from any window or other opening into the conditioned spaces of the building that is less than 2 feet (610 mm) below the exhaust point, and 10 feet (3048 mm) from any window or other opening in adjoining or adjacent buildings.

    B201.7 Passive subslab depressurization system.
    In basement or slab-on-grade buildings, the following components of a passive subslab depressurization system shall be installed during construction.

    B201.7.1 Vent pipe.
    A minimum 3-inch-diameter (76 mm) ABS, PVC or equivalent gas-tight pipe shall be embedded vertically into the subslab aggregate or other permeable material before the slab is cast. A “T” fitting or equivalent method shall be used to ensure that the pipe opening remains within the subslab permeable material. Alternatively, the 3-inch (76 mm) pipe shall be inserted directly into an interior perimeter drain tile loop or through a sealed sump cover where the sump is exposed to the subslab aggregate or connected to it through a drainage system.

    The pipe shall be extended up through the building floors, terminate at least 12 inches (305 mm) above the surface of the roof in a location at least 10 feet (3048 mm) away from any window or other opening into the conditioned spaces of the building that is less than 2 feet (610 mm) below the exhaust point, and 10 feet (3048 mm) from any window or other opening in adjoining or adjacent buildings.

    B201.7.2 Multiple vent pipes.
    In buildings where interior footings or other barriers separate the subslab aggregate or other gas-permeable material, each area shall be fitted with an individual vent pipe. Vent pipes shall connect to a single vent that terminates above the roof or each individual vent pipe shall terminate separately above the roof.

    B201.8 Vent pipe drainage.
    All components of the radon vent pipe system shall be installed to provide positive drainage to a suction pit beneath the slab, or to the ground beneath the slab or soil-gas-retarder. The slope of vent piping shall be not less than 1/8 unit vertical in 12 units horizontal.

    B201.9 Vent pipe accessibility.
    Radon vent pipes shall be accessible for future fan installation through an attic or other area outside the habitable space.

    Exception: The radon vent pipe need not be accessible in an attic space where an approved roof-top electrical supply is provided for future use.

    B201.10 Vent pipe identification.
    All exposed and visible interior radon vent pipes shall be identified with at least one marking on each floor and in accessible attics. The marking shall read: “Radon Reduction System.”

    B201.11 Combination foundations.
    Combination basement/crawl space or slab-on-grade/crawl space foundations shall have separate radon vent pipes installed in each type of foundation area. Each radon vent pipe shall terminate above the roof or shall be connected to a single vent that terminates above the roof.

    B201.12 Power source.
    To provide for future installation of an active submembrane or subslab depressurization system, an electrical circuit terminated in an approved box shall be installed during construction in the attic or other anticipated location of vent pipe fans. An electrical supply shall also be accessible in anticipated locations of system failure alarms.

    SECTION B202
    REFERENCED STANDARDS

    ASTM
    C 33-08Standard Specification for
    Concrete Aggregate
    B201.1
    C 920-11Standard Specification for
    Elastomeric Joint Sealants
    B201.5.1
    B201.5.2
    B201.5.5
    E 1643Standard Practice for Selection,
    Design, Installation, and
    Installation, and Inspection of
    Water Vapor Retarder Used in
    Contact with Earth or Granular
    Fill Under Concrete Slabs
    B201.6.2
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