Mitigation Specific Definitions

It is important for radon measurement and mitigation students to take special note of the definitions in this section as compared to the general definitions found in the course glossary. These definitions are standard in construction.

ACTIVE SOIL DEPRESSURIZATION (ASD) — a family of radon mitigation systems involving mechanically-driven soil depressurization, including sub-slab depressurization (SSD), sump pit depressurization (SPD), drain tile depressurization (DTD), hollow block wall depressurization (BWD), and sub-membrane depressurization (SMD).

ADDITION. A building extension or increase in floor area that can be occupied or that exchanges air with the conditioned space of the building.

AIR DISTRIBUTION SYSTEM – For the purposes of this standard, the air distribution system components which include ducts, plenums, air handlers, furnaces, single-package air conditioners, etc.

BACKDRAFTING — a condition where the normal movement of combustion products up a flue (due to the buoyancy of the hot flue gases), is reversed, so that the combustion products enter the building (see pressure-induced spillage).

CAULKS AND SEALANTS – Those materials which will significantly reduce the flow of gases through small openings in the building shell. Among those used are urethane, mastic, epoxy,

COMMUNICATION TEST – a diagnostic test to evaluate the potential effectiveness of a sub-slab depressurization system by applying a vacuum beneath the slab and measuring, either with a micro manometer or with a heatless smoke device, the extension of the vacuum field. Also called pressure-field extension test.

CONDITIONED FLOOR AREA – The horizontal projection (outside measurements) of that portion of space which is conditioned directly or indirectly by an energy-using system.

CONDITIONED SPACE – All spaces, which are provided with heated and/or cooled air or which are maintained at temperatures over 50ºF (10°C) during the heating season, including adjacent connected spaces separated by an uninsulated component (e.g., basements, utility rooms, garages, corridors).

CONTRACTION JOINT – A formed, sawed, or tooled groove in a concrete slab to create a weakened plane and control the location of cracking resulting from drying and thermal shrinkage (also sometimes called control joint).

CONTRACTOR — for the purposes of this practice, a contractor is one who contracts to performs radon reduction activities or is an employee of one who contracts to perform or performs radon reduction activities, with the expectation that payment will be received for the work performed. A person who does radon reduction activities as an employee of a building owner is also a contractor for purposes of this standard practice. Persons whose normal activity is not radon reduction, but who do work related to radon reduction like indoor air quality consultants, radon consultants, plumbers, building contractors, or employees of these persons are all viewed as contractors when performing radon reduction activities covered by this practice.

CRAWL SPACE – The unconditioned space between the lowest structural member of the floor and the earth. The crawl space is created when the floor spans between structural supports rather than being directly supported by the earth beneath the floor.

CRAWLSPACE DEPRESSURIZATION (CSD) (active) — a radon mitigation technique designed to achieve lower air pressure in the crawlspace than in the rooms bordering and above the crawlspace. A radon fan, draws air from the crawl space and exhausts that air outside the building. Crawlspace depressurization (CSD) is intended to mitigate rooms bordering and above the crawlspace but not the crawlspace itself. All CSD systems, for purposes of this practice, are active.

DEPRESSURIZATIONa negative pressure induced in one area relative to another.

DIAGNOSTIC TESTS — procedures used to identify or characterize conditions under, beside and within buildings that may contribute to radon entry or elevated radon levels or that may provide information regarding the performance of a mitigation system.

ELASTOMERIC – That property of macromolecular material of returning rapidly to approximately the initial dimensions and shape, after substantial deformation by a weak stress and release of stress.

EPOXY – A thermosetting resin characterized by adhesiveness, flexibility and resistance to chemicals and used chiefly as a coating or adhesive.

HIGH RANGE WATER REDUCER – A chemical admixture added to the concrete capable of reducing the water content at least 12 percent. This admixture should conform to ASTM C 494 Type F or G.

HVAC – Heating, ventilating and air conditioning.

INFILTRATION BARRIER – A product or system designed to limit the free passage of air through a building envelope component (wall, ceiling or floor). Such products and systems may be continuous or non-continuous discrete elements which are sealed together to form a continuous barrier against air infiltration.

MANUFACTURED SANDS – Sands resulting from the crushing of rock, gravel or slag.

MASTIC – A sealant with putty-like properties.

MIDRANGE WATER REDUCER – A water reducing admixture capable of reducing water content from 6 to 15 percent. This admixture should conform to ASTM C 494 Type A and or F.

MITIGATE – Make less severe, reduce, relieve.

NATURAL SANDS – Sands resulting from the natural disintegration and abrasion of rock.

OCCUPANCY – The purpose for which a building or part thereof is used or intended to be used. For the purposes of determining changes of occupancy for this code, the occupancy should be considered the major occupancy group designations established by the locally adopted building code.

OUTSIDE AIR – Air taken from the outdoors and, therefore, not previously circulated through the system.

PASSIVE RADON PROTECTION SYSTEM – Indoor radon reducing building design, material, or construction features that increase the barriers to radon entry and require no mechanical operation, operating costs, or user attention beyond normal home maintenance (such as re-caulking floor cracks, etc.)

PERM – Unit of measurement of the water vapor permeance of materials – Value of one perm is equal to one grain of water vapor per square foot hour per inch of mercury vapor pressure difference.

PICOCURIE (pCi) – A unit of measurement of radioactivity. A curie is the amount of any radionuclide that undergoes exactly 3.7 x 1010 radioactive disintegrations per second. A picocurie is one trillionth (10-12) of a curie, or 0.037 disintegrations per second.

PlCOCURIE PER LITER (pCi/L) – A common unit of measurement of the concentration of radioactivity in a gas. A picocurie per liter corresponds to 0.037 radioactive disintegrations per second in every liter of air.

POLYSULFIDE RUBBER – A synthetic rubber characterized by impermeability to gases and used in adhesives, binders and sealing compositions and in coatings.

RADIUM (Ra) – A naturally occurring radioactive element resulting from the decay of uranium. For the purposes of this standard, radium applies to radium-226. It is the parent of radon gas.

RADON – A naturally occurring, chemically inert, radioactive gas. It is part of the uranium-238 decay series. For the purposes of this standard, radon applies to radon-222; thus, it is the direct decay product of radium-226.

REMOTE SPACE – A space isolated from the main conditioned area of a building by intermediate non-conditioned spaces.

RESIDENTIAL BUILDING – Residential occupancies which include single-and multiple-family buildings that are three or fewer stories above grade. Hotels, motels and other transient occupancies are considered nonresidential buildings for the purpose of this standard.

SLUMP – A measure of the relative consistency or stiffness of fresh concrete mix, as defined by ASTM C 143.

SOIL GAS – Gas that is always present underground, in the small spaces between particles of the soil or in crevices of rock. Major constituents of soil gas include air and water vapor. Since radium-226 is essentially always present in the soil or rock, trace levels of radon-222 also will exist in the soil gas.

SUBSTRUCTURE MEMBRANE – Flexible, non-degrading material sheet placed between the soil and the building for the purpose of reducing the flow of soil gas and moisture into the building. Examples are: polyethylene, ethylene propylene diene terpolymer (EPDM), neoprene, and cross laminated HDPE.

URETHANE – A crystalline ester-amide used as a gelatinizing agent for cellulose acetate or cellulose nitrate. A component of polyurethane used in making flexible and rigid foams, elastomers, and resins for coatings and adhesives.

VENTILATION – The process of supplying or removing air, by natural or mechanical means, to or from any space. Such air may or may not have been conditioned.

WATER-REDUCING ADMIXTURE – A chemical additive to concrete capable of increasing its flowability without increased mixing water, without set retardation, and without increased air entrainment.