Number of employees?
If you want to start a roofing company (based on your impression). You will need a large amount of capital and instant customer base to achieve any type of immediate success.
The typical scenario would be a disagreement between partners and one decides to break away to start his own firm or some type of "capital venture" guru looking to make money from a storm damaged area, invest in a roofing business to reap quick profits. Both require employees to run.
Typical startups: Everything is run by the roofer (taxes, venors, wages, etc.) until a little capital start rolling in where he is able to outsource some things (accountant, lawyer, advertisment, etc). No employees are needed at the beginning. Family members may help out at times to facilitates some things, but usually very minimal
While the company is growing, you may hire laborers to help you do some of the work (should be done over the table and NOT under it). An owner can typical a have a crew of 4 persons to do all the work while you estimate, bid, and do accounting....any more, you will be stretched really thin.