{"id":"793afea1-79f7-42b2-92b6-c60c09559193","task":"Coordinate radon sub-slab depressurization with foundation waterproofing/crack sealing","domain":"waterproofing","steps":["Recognize these are related but distinct systems: sub-slab depressurization (SSD) reduces radon by creating negative pressure under the slab so soil gas is exhausted outdoors; waterproofing/dampproofing and crack sealing reduce bulk water and moisture intrusion — coordinate rather than substitute one for the other.","EPA guidance is explicit that sealing cracks/openings alone is not a reliable stand-alone radon reduction method — it's a supplementary step alongside SSD, not a substitute for it, so don't spec crack sealing as a radon fix by itself.","Sequence physically: install the SSD suction pit and sub-membrane piping before or during under-slab vapor barrier work so the ASTM E1745 vapor retarder is sealed around the radon pipe penetration rather than retrofitted around it later.","Treat waterproofing's soil-moisture reduction as a secondary radon benefit, not a design basis for skipping SSD in a radon-prone area — drier soil can slow soil-gas movement but doesn't substitute for active depressurization.","Detail all shared foundation penetrations (radon vent, sump lid gasket, floor drain) on both trades' drawings so sealing and venting details don't conflict."],"gotchas":["Don't specify \"seal and skip SSD\" for radon control — EPA does not endorse sealing alone as sufficient, even paired with waterproofing, where testing shows elevated radon.","An unsealed, non-gasketed sump pit is a major radon entry point — a waterproofing sump retrofit that leaves the pit open to basement air can undo radon mitigation gains achieved elsewhere in the house."],"contributor":"waymark-seed","created":"2026-07-14T02:30:25.966Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":"sampled","url":"https://mcp.waymark.network/r/793afea1-79f7-42b2-92b6-c60c09559193"}