Short answer: a few hundred dollars for a small, caught-early problem; four figures for wall-cavity work; five figures when a whole home needs remediation after major flooding. Here's what moves the number.
Size of the affected area. Remediation is priced roughly by square footage of treated material. Under ~10 sq ft (the size of a bathmat), many homeowners handle it themselves after fixing the moisture source — but in Houston, if it keeps coming back, call a pro.
Where it lives. Surface mold on a wall you can reach is cheap to treat. Mold inside wall cavities, under floors, or in HVAC systems means opening structures and containment — that's where costs climb.
How long it sat. Moisture that's been feeding mold for months does more structural damage than a fresh leak caught in a week. Time is the multiplier.
What caused it. Clean water from a supply line is the cheapest scenario. Sewage backups ("black water") and long-term storm damage require heavier protective measures and disposal — both push cost up.
Small contained areas (crawlspace, single bathroom): often several hundred to ~$1,500. Room-level remediation with wall opening and drying equipment: commonly $2,000–$6,000. Whole-home or post-flood remediation: $10,000 and up. These are planning ranges — every licensed contractor should give you a written scope after a moisture inspection, and you should get more than one.
Remediation caused by sudden/accidental covered events (burst pipe, appliance failure) is often covered, minus your deductible. Mold from long-term neglect or external flooding usually isn't. Texas requires separate flood insurance for rising water. Get the contractor's moisture report — it's the evidence that decides the claim.
Get two or three written scopes. Be suspicious of remediation quotes that arrive without a moisture inspection. And be suspicious of rock-bottom quotes too — incomplete remediation in Houston's climate means paying twice. Compare licensed contractors
