Exempt buildings are as follows:
- Buildings of classifications not listed in Section F103.1, Applicability, and
- Residential buildings built on piers or pilings that elevate the bottom of the floor joists a minimum of 18 inches (457 mm) above grade, which do not have skirting or stem walls that restrict air ventilation, and which comply with the following additional provisions:
- The perimeter of the building from the ground plane to the lower surface of the floor shall be totally open for ventilation, except for the occurrence of enclosures complying with Item c below.
- All pilings, posts or other supports shall be solid, or if hollow, shall be capped by an 8-inch (203 mm) solid masonry unit or sealed by a permanent barrier that is impermeable to air flow.
- Enclosures of any kind, including chases, storage rooms, elevator shafts and stairwells, etc., that connect between the soil and the structure shall be sealed at the surface of the soil to comply with the sealing provisions of Chapter F3 and shall have a soil contact area of less than 5 percent of the total building floor area.
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. 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.
Epoxy. A thermosetting resin characterized by adhesiveness, flexibility and resistance to chemicals and used chiefly as a coating or adhesive.
Polysulfide rubber. A synthetic rubber characterized by impermeability to gases and used in adhesives, binders and sealing compositions and in coatings.
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 50°F (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).
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.
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.
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 noncontinuous 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 shall conform to ASTM C494, 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 shall 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 recaulking floor cracks, etc.).
PICOCURIE (pCi). A unit of measurement of radioactivity. A curie is the amount of any radionuclide that undergoes exactly 3.7 × 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.
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.
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.
SOIL GAS. Gas which 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, nondegrading 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, ethylenepropylene diene terpolymer (EPDM), neoprene, and cross-laminated HDPE.
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.
Slabs and foundations shall be constructed using a slab edge detail that eliminates cracks that could connect the house interior to subslab soil and is consistent with other construction constraints such as terrain. Monolithic slab construction should be used where possible. Only the following slab edge detail options may be used:
- Thickened edge monolithic — the subslab membrane shall extend beyond the outside face of the slab edge.
- Slab poured into stem wall — where concrete blocks are used as slab forms, the subslab membrane shall extend horizontally at least 1 inch (25.4 mm) into the stem wall, but shall not extend upward along any vertical faces of the stem wall. The concrete slab shall be poured into the stem wall to completely fill its open volume to form a continuous and solid stem wall cap of minimum 8 inch (203 mm) thickness. Framed exterior walls shall be sealed or gasketed to the slab.
- Slab capping stem wall — where the floor slab is formed and placed to completely cover the stem wall, the subslab membrane shall extend horizontally beneath the slab to its outer edge. The supporting stem wall shall be capped with a solid masonry unit of at least 4 inch (102 mm) thickness beneath the membrane and the slab.
Vertical joints through slabs shall be formed with a recess of not less than 1/4 inch by 1/4 inch (6.4 by 6.4 mm) and sealed with an approved sealant.
Plastic pipes shall be in contact with the slab along the slab's depth by casting the concrete tightly against the pipe. Where pipes are jacketed by sleeves, they shall be sealed by one of the following methods:
- Formation of a slot in the slab around the pipe and casting with asphalt or an approved sealant from the slab to a point above the sleeve, or
- Seal the space between the sleeve and the pipe with an appropriate joint sealant (see Section F303.6).
- Pipes and wiring penetrating the slab through chases or conduit shall be sealed by placing an approved sealant between the pipe or wiring and chase or conduit. Plastic sheath, foam or insulation material shall not be used alone around pipes or conduit for sealing purposes.
- Where multiple pipes are ganged, block out a work space around the multiple pipes and seal as in Section F303.3.4.2.
Mix designs for all concrete used in the construction of slab-on-grade floors shall specify a minimum design strength of 3,000 psi (20.7 MPa) at 28 days and a design slump not to exceed 4 inches (102 mm). On-site slumps shall not exceed 5 inches (127 mm), provided total water added to the mix including plant, transit and site added water does not exceed the following parameters:
Concrete slabs shall be cured continuously after pouring according to one of the following procedures:
- Moist curing by means of ponding, fog spray or wet burlap for at least 7 days.
- Moist curing using impermeable cover sheet materials conforming with ASTM Cl71 for at least 7 days.
- Curing with liquid membrane forming compound according to manufacturer's specifications and conforming with ASTM C309.
Curing compounds shall be compatible with materials specified in Section F303.6.
Slabs shall have a subslab membrane, conforming with Section F302 that extends to the slab perimeter, but does not vertically separate the slab from the foundation wall. The slab and membrane shall be placed in accordance with Section F303, or may use a floating slab design with all of the following conditions: