Ordinary cleaning does not get rid of mold, grim, dust and mud only powerful thorough cleaning with power washer can get the job done rightly. They are classified into different categories depending to the type of fuel/energy they consume. Different power washers included electric, diesel, petrol, gas and ultra high. Some models allow into the water stream detergent in combination with a particular nozzle to maximize the cleaning process. Electric and gas powered units are preferred due to easy usage as they can be plugged into a normal outlet that there was pressure up to about 2000PSI.