SGM-SF_2017with 12/20 Revisions

Non-ASD Methods 46 ANSI/AARST SGM-SF 2017 (with 1220 revisions) Soil Gas Mitigation Standards for Existing Homes Informative advisory —Soil gas should be expected to contain a variety of hazards that may include: highly concentrated radon gas or other gases that may be toxic or combustible; vapors that can contain hazardous concentrations of chemical compounds; and, quite normally, dense water vapor that can enhance biological growth once having entered a building. 12.3.5 Prior to system installation or augmentations: a) A Qualified Ventilation Technician shall employ pressure and airflowmeasurements as needed to evaluate system capacity requirements for the design stipulated in Section 12.3.1 . Note—Blower door measurements during system design are recommended to quantify the capacity needs of the system; b) Sources for air to be delivered to the airspace shall be evaluated for viability of meeting requirements in Section 12.2 .; and c) An attempt shall bemade to evaluate the potential that pressurization might inadvertently transport radon to other airspaces, in accordance with Section 12.3.4 . 12.3.6 After installation or augmentations: a) A Qualified Ventilation Technician shall verify with pressure and airflow measurements that adequate capacity for required operating parameters stipulated in Section 12.3.1 were achieved. Thesemeasurements shall be recorded in accordance with Section 10.1.2 and often include : total airflow in and total airflow out, temperature in and temperature out, air density, altitude and other operating parameters; b) Sources for air delivered to the airspace shall be verified for compliance with Section 12.2 ; and c) An attempt shall be made to verify if the system is inadvertently transporting radon to other airspaces, in accordance with Section 12.3.4 ; and 12.3.7 A long-term OM&M plan is required in accordance with Section 13.7 . 12.4 Soil Air Pressurization Note—Establishing positive pressure in the gas permeable layer or airspace between occupiable spaces and the soil can, under certain conditions, be effective to stop radon entry. Active Soil Pressurization can, in some cases, be achieved with permanently installed mechanical systems where an air source fromupper floors or outdoors is ducted into the gas permeable layer under the foundation or airspace in contact with soil. Where airflow ( cfm ) needs are similar, Active Soil Pressurization systems might resemble inversely-applied ASD systems. Informative advisory —These upside-down systems have more often been employed for special conditions in which natural sub-slab aggregates are so porous that establishing a vacuum under the foundation is not possible. When Soil Air Pressurization is employed: 12.4.1 Sources for air Sources for air delivered to the airspace being pressurized shall comply with Section 12.2 . 12.4.2 Sealing Sealing shall be in compliance with Section 7 in order to help break the connection between soil air and living spaces. 12.4.3 Unintentional radon transport Considerations shall be made during design with attempts to verify after installation that radon is not transported to another airspace or occupiable portion of the building in accordance with Section 12.3.4 . 12.4.4 A long-term OM&M plan is required in accordance with Section 13.7 .