DIY Mold Cleanup or Call a Pro? A Houston Homeowner's Decision Guide
Updated October 7, 2026 · 2 min read
When it's reasonable to clean mold yourself, how to do it safely, and the signs that you need a licensed professional.
Not every spot of mold needs a contractor. The EPA's guidance and common practice put a rough dividing line at about 10 square feet (a 3 ft by 3 ft patch) for homeowners to clean themselves, if the cause is understood and fixed, and the material is non-porous or easily cleaned.
Reasonable to DIY
- Surface mold on tile, grout, glass, sealed wood, metal or plastic
- A small patch (under ~10 sq ft) on a painted wall where the cause is a fixed, known source, like a bathroom without a fan
- No one in the home is immunocompromised, and you can wear an N95 respirator, gloves and goggles
How: fix the moisture first. Mist lightly to keep dust down, scrub with detergent and water, wipe with clean damp cloths, dry quickly within 24 to 48 hours, and bag the rags. Bleach isn't necessary and is ineffective on porous materials; never mix bleach with ammonia or vinegar.
Call a professional if
- The area is 25 sq ft or more (a protocol and licensed contractor are required under Texas law) or you're unsure how large it is
- It's inside walls, above ceilings, in the attic or in HVAC
- It followed flooding or sewage
- The mold keeps coming back after cleaning, which means the moisture source is still active
- Anyone in the home has asthma, allergies, a weakened immune system, or is pregnant or very young or old
- You're selling and need documentation, or filing an insurance claim
The moisture rule
Mold is a moisture problem. Keep indoor relative humidity between about 30 and 50% (a $15 hygrometer tells you), run bath and kitchen fans to the outdoors, fix leaks within 24 to 48 hours and keep A/C drain lines clear. See the humidity playbook at Mold Macro for the science.
What not to do
- Don't paint or caulk over mold
- Don't fog, bomb or "encapsulate" without removing the source
- Don't dry-scrub or sweep; you'll aerosolize spores
- Don't run a fan that blows spores through the rest of the house