[photon]

Bleach will likely not kill it either, depending on what kinds of mold it is.

really the only way to truly do it properly is to physically remove it, but as GATW said that can cause really bad problems with respect to air.

I knew some people who did this for insurance, and for houses what they did was seal it off from the rest of the house, create a negative air pressure zone so it didn't get everywhere else (i.e. everyone's lungs) and wear respirators and gear and sand/scrape the affected areas until it's all gone. Because it's in the garage you probably don't have to do the negative air pressure, just good ventilation and proper gear to protect yourself.

They said depending on the mold (and a house can have hundreds or thousands of different kinds of mold at any time) there really aren't good chemicals to treat it, it's really tough stuff. And putting chemicals on it just causes it to release its spores which can be toxic, and will grow again later if the conditions are ok, whereas physically removing it (sanding scraping) works better.

That's what he told me anyway how they did it for insurance.