Attic Mold Removal in Kent, WA

My roof is only a few years old. Why is there mold in the attic?

Because the roof isn't usually the problem. Most attic mold in Kent homes forms on the underside of perfectly sound roofs. East Hill is primarily residential, West Hill mixes homes and businesses along I-5, and the valley floor has some medium-density housing; in all of them, warm air from showers, cooking and breathing rises into the attic through gaps around light fixtures, the hatch and wiring holes. A bath fan that vents into the attic adds even more. Through the October-to-April stretch the sheathing stays cold, so that moisture condenses on it night after night. If the soffits are buried under insulation, there's no airflow to carry it away.

How do I tell condensation from a leak?

Look at the pattern. Condensation leaves widespread staining across a whole slope, often worse on the side that gets the least sun, and frost or rust on nail tips. A leak leaves a concentrated stain, usually around a chimney, vent pipe, skylight or valley, and wet insulation directly below it. Heavy rain can expose a weak spot. Kent went through back-to-back atmospheric rivers in December 2025, when a levee failure led King County to order evacuations in parts of the city, and a stretch like that is a good reason to check under the roof afterward. Many attics have both problems at once.

What does removal involve, and what does it cost?

A remediation company should inspect the attic, take moisture readings and write up a scope. Typical work includes correcting the moisture source, removing wet or moldy insulation, cleaning the sheathing and rafters by HEPA vacuuming, scrubbing or media blasting, replacing any decking that's gone soft, and reinsulating once the wood is dry. Angi's Seattle cost guide puts attic mold removal at $825 to $3,300; HomeGuide's 2026 national ranges are $1,500 to $6,000 for part of an attic and $6,000 to $15,000 for a full attic. Washington has no state mold license or certification, so check the company's construction contractor registration on L&I's Verify a Contractor tool.

One Kent note

If the job turns into sheathing replacement, reroofing or new wiring for a bath fan, ask the City of Kent what permits apply before that work starts.