Washington radon requirements for new construction
Washington State Building Code, 2021 IRC portion, WABC 2021 §1202.7
What your permit set must show
- Washington's requirement is different from most other jurisdictions we track: it requires a complete radon control system, not just a passive rough-in, within designated Zone 1 areas.
- Outside Zone 1, the requirement applies only where the building design includes an unvented crawl space.
- Because this is a full-system requirement rather than a rough-in-only requirement, a Washington permit set needs to show the complete control system per WABC 2021 §1202.7, not just the passive stub used in rough-in-only jurisdictions.
Common questions
Is Washington the same as other rough-in-only states?
No. Washington's building code (WABC 2021 §1202.7) requires a complete, active radon control system in Zone 1 — not just the passive rough-in required in most other jurisdictions we track.
Do I need this if I'm outside Zone 1?
Only if your design includes an unvented crawl space. Otherwise, the statewide requirement does not apply outside Zone 1.
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