RMS-LB 2018 with 12/20 Revisions

Note—12/20 revisions — (This Section is now identical for AARST: SGM-SF, RMS-MF and RMS-LB) ANSI/AARST RMS-LB 2018 (with 1220 revisions) Radon Mitigation Standards for Schools and Large Buildings 30 7.0 SEALING 7.1 Background and Accessibility Sealing is not to be regarded as a permanent, stand-alone mitigation method. The purpose and viable goal of sealing efforts are limited to achieving a continuous air barrier that resists air movement between soil and indoor air. Note—The use of sealing alone has not been shown to significantly or consistently reduce radon entry into buildings. 7.1.1 Accessibility to cracks and openings For the purpose of sealing requirements herein, the term “accessible” shall mean accessible without destructive or significant disassembly of building components or finishes. Inaccessible openings or cracks shall be disclosed to the client and included in operation, maintenance and monitoring ( OM&M ) documentation if they may compromise the performance of a mitigation system and are determined to be beyond the ability of the contractor to seal. 7.2 Sealant Materials 7.2.1 Caulking cracks When sealing cracks in slabs or foundation walls, the caulks and sealants shall be durable materials, such as urethane or polyurethane, complying with ASTM standard C920 class 25 or greater or equivalent material. Caulks and sealants shall be applied according to the manufacturer’s recommendations. Informative advisory —The chances of adverse effects on occupants from exposure to curing compounds are likely to increase with increased volumes of product application. When using such products, it is recommended to notify occupants of related hazards, such as illustrated in Exhibit C . Products that emit low volumes of chemical vapors during curing are recommended for protection all occupants and prospective occupants as a public health matter, and especially for sensitive occupants. 7.2.2 For larger gaps Where a crack or joint is greater than 1/2 inch (13 mm) in width, foam backer rod or other comparable filler material to support wet caulk until it cures shall be inserted into the existing gap prior to applying caulk. 7.2.3 For larger openings When sealing larger openings to soil in slabs and foundation walls, the materials shall be durable, such as: nonshrink cementitious products; expanding foam; plastic; or other comparable materials and methods appropriate for the application. 7.2.4 For heated pipes and flues When sealing openings around combustion appliance flues and hydronic heat or steam pipes, noncombustible materials shall be used. 7.2.5 For sump lids and hatchway doors For sump lids, hatchway doors or other items that require access in the future, nonpermanent sealant materials are required, such as silicone caulk, gasket materials or other equivalent method. 7.3 Accessible Slab Cracks Accessible openings to soil around suction piping, utility penetrations and where the slab meets the foundation wall shall be closed or sealed to resist air movement between soil and indoor air. Informative advisory —Accessible cracks across a slab that are greater than 1/16 inch (1.6 mm) in width should also be sealed. It is further recommended to seal accessible expansion or control joints in a slab.