I thought industry standard for sales commission was 10%.
I have wrestled in the past trying to make something work with another guy. We hemmed and hawed and couldn't come up with anything that appealed to us both. Then a year later he closed up and came to work for me, which was the best possible scenario, and it still was a huge headache until I finally let him go.
I wouldn't look at it as a partnership. I'd look at it as he can be your top man with profit sharing and incentives. I wouldn't give up control over decisions that affect the direction I want to steer my company, such as where to invest profits, etc.
So if he is really going to be just a salesman, I don't know what percentage to use, 30% of net profit sounds fine to me. But one rule of negotiation I've heard before is first one to name a price (or term) loses. Ask him what he thinks is a good arrangement. He might say 20%.
Also don’t forget that job costing is one of the biggest headaches of contracting. Getting good numbers and tracking them, especially when the schedule gets really busy. Who is going to track all this info to decide who gets how much? Just make sure that expense gets thrown in before you start calling things profit.
