Legal Question in Construction Law in California

I assume you mean 10% profit. The question is, 10% on top of what? Many contractors bid at 10% over their costs, but the costs can include materials at retail, labor at $XXX per hour, etc., likely reflecting more than actual out-of-pocket costs. Successful bidding is an art. I'm guessing you haven't been in the commercial business long, or you'd have a feel for what the market will take. My advice is to tread lightly and bid on smaller projects until you gain more confidence. Better to lose a few bids than to be too low and lose a chunk of your capital.