Reducing Radon in New Construction of ANSI/AARST CCAH 2020 1 & 2 Family Dwellings and Townhouses 11 SECTION 404 SEALING SOIL GAS COLLECTION PLENUMS 404.1 General sealing of soil gas collection plenums. Sealing of potential soil gas pathways shall be in accordance with Sections 404.1.1 through 404.1.6. 404.1.1 Sumps in floors. Sumps in interior floors shall have a rigid lid and the lid shall be sealed with a gasket or a non-permanent caulking, such as silicone caulk and mechanically fastened in a manner to facilitate removal for maintenance. Pipe and wiring penetrations through the lid shall be sealed. The intersection of the floor and sump basin shall be sealed with a caulk complying with ASTM C920 class 25 or higher. 404.1.1.1 Label sump basins. Sump basin covers shall be identified with a durable label that reads “Component of a Radon Reduction System. Do not tamper with or disconnect.” or equivalent wording. The lettering on the label shall be not less than 1/4 inch [6.35 mm] in height and shall be of a color in contrast to the color of the background on which the lettering is applied. 404.1.2 Hollow masonry unit walls. The top course of hollow block masonry walls shall be made of solid masonry units or the top course shall be fully grouted. The top course under the full width of door and window openings shall be made of solid masonry units or the hollow masonry units shall be fully grouted. Where a brick veneer or other masonry ledge is installed, the course immediately below that ledge shall be made of solid masonry units or the top course shall be fully grouted. Other penetrations through foundation walls shall be sealed. 404.1.3 Floor drains. Floor drains and condensate drains shall not allow soil gas entry. 404.1.4 Air ducts. Air ducts located below concrete slabs shall be sealed to prevent radon entry and constructed in accordance with the International Residential Code (IRC). 404.1.5 Foundation drains. Foundation drainage systems with openings to the atmosphere shall include a backwater valve or other means to isolate the soil gas collection plenum from any openings to atmosphere. Access shall be provided for maintenance. 404.1.6 Access openings. Access openings in the floor provided for drain maintenance shall not allow soil gas entry.