Black mold on porous materials cannot be reliably cleaned in place - it has to be contained and removed. A proper job seals off the area, runs HEPA filtration, physically removes contaminated drywall, carpet, or insulation, treats the framing, and fixes the moisture source. Bleach only lightens the surface; the EPA does not recommend it for remediation.
How to remove black mold, step by step
Contain the area first
Disturbing mold without sealing the area first sends spores through the rest of the home, which is why professionals build containment and run negative-air HEPA scrubbers before they touch anything. Containment is what keeps a small problem from becoming a whole-house problem.
Remove it - don't just clean it
Mold roots (hyphae) grow into porous material, so wiping or bleaching the surface leaves the root structure behind and the colony returns within days. On non-porous surfaces like tile or metal, a small fresh spot can sometimes be cleaned instead - everything else has to be physically removed.
Fix the moisture source
Black mold means water has been present. Unless the leak, humidity, or drainage issue is fixed, new mold grows on the new materials - IICRC S500 drying and verification is what makes the fix permanent, and it is the step that actually stops it coming back.
Related questions, answered
Is black mold dangerous?
Black mold can cause health problems, especially for people with allergies, asthma, or weakened immune systems - coughing, congestion, eye and throat irritation, and worse for the sensitive. No mold indoors is desirable, and color alone does not identify the species. Any significant growth should be removed by containment and remediation, not disturbed. More on this
Does bleach kill mold?
Not on the surfaces that matter most. Bleach is made for hard, non-porous surfaces. On porous materials such as drywall, wood, and insulation it does not reach the root structure, so the mold grows back. The U.S. EPA does not recommend bleach as a routine mold-remediation tool. More on this
