Mold issue after tenant

[Mats Daniel Skrede]

Hello, 

We have some mold on the drywall after some tenants moved out. They told us that they had attempted to wash it away, but it came back. We got some mold inspectors to check on it and they told us that it is probably due to poor ventilation in the apartment and the mold appeared in this corner of the living room due to the isolation not being great, making it colder than the other areas of the apartment. They only did a visual inspection.

We have no experience with mold issues, so we are looking to see what you bright minds here think? Would we need to do a test inside the wall to look for moisture? 

And, would we need to replace the drywall, or should we be able to kill off the mold and be fine? We will of course fix the ventilation and/or get a dehumidifier. 

[Nathan Gesner]

Quote from @Mats Daniel Skrede:

One cup of clorox and a gallon of water. Apply to the surface and do not rinse. Mix a 50/50 of ammonia and water. Spray on the surface and wait 2-3 hours, then wipe clean. 

There are cleaning products specifically designed to remove mold and prevent it from coming back.

Mold requires two things: moisture and food (dust is sufficient). You have to remove the source of moisture to prevent it from coming back. That could be as simple as installing a ventilation fan in that area.