SGM-SF_2017with 12/20 Revisions

Building Investigations Prior to Design 7 ANSI/AARST SGM-SF 2017 (with 1220 revisions) Soil Gas Mitigation Standards for Existing Homes 1. air volume capacity needed to overcome leakage from any side of the soil gas collection plenum such as at the soil or at foundation cracks; and 2. vacuum strength needed to overcome indoor air pressures and resistance posed by fill materials within the soil gas collection plenum . 5.5.1.1 Quantitative Measurements When conducting PFE Analysis , it shall be conducted using a differential pressure gauge that is: a) capable of reading to 1/1000 inch water column (.25 Pa); and b) calibrated in accordance with national standards or manufacturers’ recommendations. 5.5.1.2 Reliance on Experience in Like Structures Note—Information gained at one structure regarding air volume and fan vacuumneeds can sometimes be applied to similar structure(s). For this consideration: a) The like structures being compared need to be of similar size, geological and sub-slab characteristics, and built with similar construction practices; b) At least one PFE measurement is made in each structure that indicates a similar distance for PFE ; and c) Sufficient additional information is gained from each structure to indicate like conditions exist. Informative advisory —Should past experiences not include mitigation efforts in like structures, a full PFE analysis is highly recommended to ensure system effectiveness and reduce unnecessary or unexpected costs of repeated retests and further remedial action. 5.5.2 Non-ASD methods Diagnostic procedures stipulated in Section 12 are required prior to installation. Subsequent verification after installation is also stipulated in Section 12 and often includes repeated diagnostic procedures and additional testing of indoor air. 5.6 Design Decisions Note—Mitigation methodology and design are dependent upon information gained from the non-destructive evaluation that is confirmed by diagnostics. The flowcharts that follow in Figure 5.6.1 and Figure 5.6.2 illustrate example procedures for determining the appropriateness and feasibility of design choices.