A commercial pressure washer ( in most pros opinions ) is a standard 4000 psi 4 gallon per minute minimum machine. In some cases, they are belt driven but usually a direct drive unit. We have separated our machines into the WorkShop, Commercial and Industrial series machines. The commercial pressure washer series offers several engines and pump options depending on your preference and what you will be using the machine for.
When I started cleaning roofs 20 years ago the pros only used belt drive machines but thanks to modern technology and better-designed units the Direct Drive Commercial Pressure Washer has quickly become the favorite among start-ups and the back up among seasoned pros. Basically, every pressure washing company will start out with a commercial machine. One of my personal favorites after years of selling, servicing and repairing the different brands is the Honda AR-RRV4G40 combo. The Honda engine is a GX390 ( 13 hp ) with an AR pump that has a bolt on unloader. This is one of the most reliable and affordable commercial pressure washers on the market.
This is a great starting point for a commercial pressure washing company. I still use one of these as a back up on most trailer rigs we build here at XSP. For a single person starting out it is light enough to lift into the back of a truck if needed. It is portable enough to allow a lot of flexibility on any job site.