Walnut Creek, CA Rental Property Rules: Mold Disclosure (2026)

California's Toxic Mold Protection Act of 2001 (Health & Safety Code §§26100-26156) requires written disclosure of known mold conditions that exceed state-established permissible exposure limits, though the Department of Public Health has not yet adopted binding PELs. In practice, landlords must disclose any visible mold affecting the unit prior to occupancy and whenever discovered thereafter. California Civil Code §1941.1 includes dampness and mold within the implied warranty of habitability — tenants may withhold rent or repair-and-deduct if a landlord fails to remediate mold caused by structural defects, plumbing leaks, or roof failures. Walnut Creek Code Enforcement (925-943-5899) investigates mold complaints under the Uniform Housing Code, citing landlords for failure to maintain weatherproof, watertight conditions. Remediation exceeding 100 square feet typically requires a licensed mold contractor. Tenants who caused the mold through poor ventilation or neglect may be held responsible. Security deposits cannot be withheld for mold caused by landlord-side maintenance failures.