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CITY of ORONO . : ( °4 Street Address: Mailing Address: O , 0 2750 Kelley Parkway PO Box 66 Orono, MN 55356 Crystal Bay, MN 55323-0066 '� I�' 47 ':� ', 4.° Radon Requirements o,1` Effective June 1, 2009 Information Handout Subfloor preparation. A layer of gas-permeable material Sumps. Sump pits open to soil or serving as the shall be placed under all concrete slabs and other floor termination point for sub-slab or interior drain tile systems that directly contact the ground and are within the loops shall be covered with a gasketed or otherwise walls of the living spaces and conditioned crawl spaces of sealed lid. Sumps used as suction point in a sub-slab the building. The gas-permeable layer shall consist of one depressurization system shall have a lid designed to of the following: accommodate the vent pipe. 1. A uniform layer of clean aggregate, a minimum of Foundation walls. Hollow block masonry foundation 4 inches thick. The aggregate shall consist of walls shall be constructed with either a continuous material that will pass through a 2-inch sieve and course of solid masonry, one course of masonry be retained by a 1/4 inch sieve. grouted solid, or a solid concrete beam at or above 2. A uniform layer of sand, a minimum of 4 inches finished ground surface to prevent passage of air from thick, overlain by a layer or strips of geotextile the interior of the wall into the living space. Where a drainage matting designed to allow the lateral flow brick veneer or other masonry ledge is installed, the of soil gases. course immediately below the ledge shall be sealed. Soil-gas-retarder. A minimum of 6-mil polyethylene or Joints, cracks, or other openings around all equivalent flexible sheeting material shall be placed on top penetrations of both exterior and interior surfaces of of the gas-permeable layer prior to casting the slab or masonry block or wood foundation walls below the placing the floor assembly to serve as a soil-gas-retarder ground surface shall be filled with polyurethane caulk by bridging any cracks that develop in the slab or floor or equivalent sealant. Penetrations of concrete walls assembly and to prevent concrete from entering the void shall be filled. spaces in the aggregate base material. The sheeting shall Waterproffing/dampproffing. The exterior surfaces cover the entire floor area with separate sections of of portions of concrete and masonry block walls below sheeting lapped at least 12 inches. The sheeting shall fit the ground surface shall be dampproofed or closely around any pipe, wire or other penetrations of the waterproofed. material. All punctures or tears in the material shall be sealed or covered with additional sheeting. Ducts. Ductwork passing through or beneath a slab shall be of seamless material unless the air-handling Entry routes. system is designed to maintain continuous positive Floor openings. Openings around bathtubs, pressure within such ducting. Joints in such ductwork showers, water closets, pipes, wires or other objects shall be sealed to prevent air leakage. Ductwork that penetrate concrete slabs or other floor located in crawl spaces shall have all seams and assemblies shall be filled with a polyurethane caulk or joints sealed by closure systems. equivalent sealant. Unconditioned crawl space floors. Openings Concrete joints. All control joints, isolation joints, around all penetrations through floors above construction joints and any other joints in concrete unconditioned crawl spaces shall be caulked or otherwise filled to prevent air leakage. slabs or between slabs and foundation walls shall be sealed with a caulk or sealant. Telephone (952) 249-4600 • Fax (952) 249-4616 • www.ci.orono.mn.us