ANSI/AARST SGM-MFLB-2023 for radon-control design
ANSI/AARST SGM-MFLB-2023 is the standard for Soil Gas Mitigation in Existing Multifamily and Large Buildings. Where CC-1000 governs design for new construction, SGM-MFLB applies when an existing large building needs a radon-control system added after the fact.
Retrofitting a large building is a different engineering problem from new construction. The slab is already poured, occupants are in place, and the design has to work with whatever sub-slab conditions and building systems already exist. SGM-MFLB sets out how to diagnose those conditions and design an effective sub-slab or sub-membrane depressurization system.
We use SGM-MFLB-2023 as the basis for retrofit design packages, producing the system layout, vent routing, and specifications a building owner or contractor needs, reviewed and signed by a certified radon professional. This is the standard most relevant to HUD-financed acquisitions and refinances of existing properties.
What the standard requires
- Applies to soil-gas mitigation in existing multifamily and large buildings
- Covers diagnosis of existing sub-slab conditions before design
- Provides design methods for sub-slab and sub-membrane depressurization retrofits
- Addresses vent routing and fan sizing within an occupied existing structure
- Serves as the retrofit counterpart to CC-1000 for new construction
Further reading
HUD Radon Requirements for Multifamily: Testing & Mitigation
What HUD multifamily financing expects for radon, and where engineered design built to the AARST standards fits.
SGM-MFLB-2023: Radon Design for Existing Large Buildings
ANSI/AARST SGM-MFLB-2023 sets the requirements for radon mitigation in existing multifamily, school, and commercial buildings, and what the design must show.
Radon Mitigation Design Package Contents for Large Buildings
What a large-building radon mitigation design set contains: collection layout drawings, barrier and sealing specifications, vent routing, and fan provisions.