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Action level
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Definition: Home owners should take action to lower radon levels indoors when levels are at or above 4 pCi/L.
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Active System
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Definition: Passive system with the addition of a fan to more actively draw radon from the soil into the stack where it dissipates into the atmosphere. A system-failure warning device (alarm) is also installed to alert the occupant if the system is not working.
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Aggregate
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Definition: A coarse material, such as gravel, placed below the slab.
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ASTM Standard Guide 1465-92
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Definition: A guidance booklet published in 1992 by the American Society for Testing and Materials according to their consensus process for deciding on the content.
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Building Code
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Definition: Criteria or requirements (i.e., minimum standards) set forth and enforced by a state or local agency for the protection of public health and safety. Is usually based on a model code (see below) and/or Model Standards published by acknowledged organizations or associations.
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Condensate drains
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Definition: Drains which remove condensation from air-conditioning or other equipment, frequently empty into the sump or below the slab.
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Condensation
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Definition: Vapor in the air turns into water on cold surfaces. Beads or drops of water (and frost in extremely cold weather) accumulate on the inside of the exterior covering of a building when warm, moisture-laden air from the interior reaches a point where the temperature no longer permits the air to sustain the moisture it holds.
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Damp proofing
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Definition: Sealing the foundation walls to prevent outside moisture from entering the basement, although not as tightly as in water-proofing.
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Drain Tile Loop
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Definition: Typically refers to a length of perforated pipe extending around all or part of the footing perimeter for draining water away from the foundation of a home.
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Flashing
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Definition: Material for reinforcing and weatherproofing the joints and angles of the roof and penetrations through the roof.
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Footing
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Definition: The supporting base for the foundation walls of a house.
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Gas-permeable
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Definition: A material through which gas passes easily.
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International Codes
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Definition: Model codes published by the International Code Council (ICC) to combine all four model building codes into one. The International Residential Code was published in early 2000.
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Junction Box
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Definition: An enclosed box used to connect or branch electrical wiring.
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Map of Radon Zones
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Definition: EPA's Map of Radon Zones assigns each of the 3,141 counties in the United States to one of three zones based on radon potential: 1) Zone 1 Counties have a predicted average indoor screening level greater than 4 pCi/L; 2) Zone 2 Counties have a predicted average indoor screening level between 2 and 4 pCi/L; 3) Zone 3 Counties have a predicted average indoor screening level less than 2 pCi/L; Elevated radon have been found in all counties (Zone 1, Zone 2 and Zone 3), see also -www.epa.gov/radon/zonemap.html
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Model Codes
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Definition: Documents specifying requirements for building, mechanical, plumbing, and fire prevention installations. Often the basis for state and local building codes.
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Model Standard
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Definition: A document that has been developed and established to connote specified consensus and approval of certain techniques and standards. A prescribed level of acceptability or an approved model used as a basis for comparison. Voluntary technical guidance until adopted into a building code. EPA has published one for radon-resistant new construction, called Model Standards and Techniques for Control of Radon in New Residential Buildings.
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Passive System
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Definition: Short for passive sub-slab depressurization system. Features to reduce radon levels by utilizing barriers to radon entry and stack effect reduction techniques and the installation of a PVC pipe running from beneath the slab to the roof. Works by using natural pressure differentials between the air in the pipe, and the rest of the home and the outside air.
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Picocuries per liter
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Definition: A unit of measuring radon levels.
Acronym: pCi/L
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Polyethylene Sheeting
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Definition: (Used as soil-gas-retarder); Plastic sheeting, about drop cloth weight, used over gravel and under the concrete slab to prevent soil gases from entering a home. The sheeting also prevents the concrete from flowing into the gravel and blocking air flow beneath the slab. Also used as a moisture barrier.
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PVC Pipe
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Definition: A hollow plastic pipe generally used for plumbing in home construction.
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Slab
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Definition: The concrete "floor" poured over the ground between the foundation walls, either at ground floor or basement level.
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Soil Gas
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Definition: Any gas emanating from the soil, including radon, methane, and water vapor.
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Stack Effect Reduction Techniques
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Definition: Features that prevent or reduce the flow of warm conditioned air upward and out of the building superstructure. If not reduced, stack effect can actually draw soil gas containing radon into the lower levels of the house. Most of these techniques are part of the International Code Council's Model Energy Code.
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Sub-Membrane Depressurization
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Definition: A system designed to achieve lower sub-membrane air pressure relative to crawlspace air pressure by use of a vent drawing air from beneath the soil-gas retarder membrane. May be a passive system (without fan) or active system (with fan).
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Sub-Slab Depressurization
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Definition: A system designed to achieve lower sub-slab air pressure relative to indoor air pressure. May be a passive system (no fan) or active system (with fan).
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Sump
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Definition: A hole going below the slab into which water is drained in order to be pumped out. Should be sealed to prevent radon from entering the home.
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Sump pit
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Definition: A hole going below the slab into which water is drained in order to be pumped out. Should be sealed to prevent radon from entering the home.
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