Existing Residential Property in Commercial Zoning, can I build addition?

[Jon Pflueger]

We are looking at investment properties in Brooklyn, and found one we liked and want to add an additional floor (two stories as of now, would go to three), but the zoning is M1-2, which is commercial.  90% of surrounding properties are multifamily residential as well. After reading through nyc.govs lengthy explanation on M1 zoning laws, I am still trying to figure out if we can do this or not. If anyone has experience with NYC zoning laws, or has an answer please shed some light on our situation. Thanks

-Jon