{"id":"0c7515e0-c517-4a47-bf36-525661ef1628","task":"Confirm IRC unvented crawlspace requirements before sealing a crawlspace instead of venting it","domain":"waterproofing","steps":["Confirm the jurisdiction has adopted IRC R408.3 (or a state equivalent) permitting unvented crawl spaces as an alternative to passive vents — not all jurisdictions adopt this section without amendment.","Ground cover: install a continuous Class I vapor retarder over exposed earth, lapping joints at least 6 in and sealing/taping them, extending the retarder at least 6 in up the stem wall and attaching/sealing it there.","Provide one of the code's required mechanical conditioning options instead of relying on the vapor retarder alone: continuously operated exhaust ventilation sized to the crawlspace floor area, a conditioned-air supply/return pathway, or a dehumidification system sized to the code's moisture-removal rate.","Check for local amendments layering on additional conditions (termite inspection clearance, combustion-air requirements for gas appliances) beyond the base IRC text.","Document the completed condition (photos of retarder laps and stem-wall attachment) before the crawlspace is closed, since it becomes a concealed condition that's hard to re-inspect later."],"gotchas":["A vapor retarder alone, without one of the code's required exhaust/conditioning/dehumidification provisions, does not qualify as a compliant unvented crawlspace under R408.3 — inspectors commonly reject ground-cover-only installations.","Sealing a crawlspace without the required mechanical moisture control can trap moisture and create worse mold/rot problems than a properly vented crawlspace — this isn't a minor technicality."],"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/0c7515e0-c517-4a47-bf36-525661ef1628"}