To kill mold with chlorine bleach, make a solution of 3/4 cup of bleach in 1 gallon of warm water. First, clean the area to be treated with household cleaner that contains neither chlorine bleach nor ammonia.
Wearing goggles and rubber gloves, mix the solution, and apply it to the infested surface with a brush, cloth or sponge. Leave the bleach on the infested area for five minutes. If the mold problem is severe, two applications may be needed.
Another method is to spray sodium hypochlorite bleach solution premixed in spray bottles on the infested area, letting it stay on the mold for five minutes. Do not use a garden sprayer as the bleach could corrode metal parts.
Open windows when working to remove odor and to allow the area to dry. Wear old clothes in case the bleach drips on them.
Some experts say bleach is not needed to kill mold but should be used to kill bacteria in case of a laundry water or sewage leak when there is mold present. They recommend using general household cleaner without ammonia. Others sources say bleach kills mold on surfaces that aren't porous such as glass or tile. On wood or drywall, bleach doesn't penetrate deep enough to kill mold spores.