She is willing to pay quite a bit to get the job done. More than enough to cover renting a hot water pressure washer from an equipment rental place.
The hot pressure washers I have seen available for rent range from 2000 psi and 2.8 gallons a minute (electric) all the way up to 3500 psi 5.0 gpm. Figured if I were to rent a pressure washer I would go with the high psi and gpm.
Besides a hot pressure washer what is the best method of attack?