Power washing or pressure washing is the only practical way to remove sludge, and mold from your house. To get the most out of a paint job you will want to pressure wash your house as well. this gives the paint a good clean surface to adhere to. Although the term is pressure wash you really do not use much pressure when it comes to your homes siding. Only low pressure is used, around 300 psi. Some contractors are ignorant of this and will try to use high pressure and this can be very dangerous as it likely will cause damage. Before hiring a contractor this should be your first question to them.
Almost all siding material can benefit from pressure washing. Hardy plank, brick, vinyl siding and aluminum will all benefit from a good cleaning from time to time. Caution should be applied when cleaning soft materials like wood but if low pressure techniques are employed then little damage is possible. Cleaning agents will need to be applied based on the type of material your exterior is made of. For most materials a mix of bleach and house cleaner will do the trick. For wood you will need to use a special cleaner that will brighten the wood and not strip out the color. All the necessary cleaning materials can be found at your local hardware store.
For a do it yourself pressure washing job, you can obtain a unit from a rental equipment store. The cost is around $50 per day. It is not necessary to get a heavy duty unit as you will be using low pressure washing to clean the house. A unit with up to 1500 psi is all you need. Although the unit can sustain 1500 psi you will want a house wash tip that will reduce the pressure. This is accomplished by using a tip with a larger opening which lowers the pressure and allows more volume to flow through the hole.
Pressure washers will have a ‘down stream’ function which sucks up the cleaning agent and mixes it with the water as it flows through the unit. Generally you will fill a 5 gallon bucket with the necessary detergent or bleach and a small hose attached to the unit is put into the bucket. Once the water begins to flow through the system, a suction develops and draws the cleaning product up and sprays it out with the water at a 1-5 to 1-7 ratio.
If using bleach to clean mildew and mold a 100% bleach solution is added to the bucket. For other cleaners you will need to consult the instructions. Be sure to remove anything from around the house that might be damaged by the bleach. A quick rinse of the flowers and shrubs usually is all that is needed to insure no plants suffer.
The best way to actually clean your house is to start at a corner. Slowly work your way across to the other end of the house. As you go spray the stream of water down at the bottom of the house and work your way up to the eves of the roof. Always work from the bottom up, this will reduce the chance for streaks to appear. Be sure to saturate every inch of the side you are working on.
If you do not then you will have spots where the bleach and cleaner did not touch. Once you get to the end of the house you will need to pull the ‘down streaming’ hose out of the cleaning solution bucket and go back over the side of the house again, this time with only clean water coming out the hose. Thoroughly rinse the siding. You should now be done with that side of the house. Put the ‘down streaming’ house back into the solution bucket and begin the next side of the house.
You will want to get close enough to the wall that you can get the solution on every inch of the siding. If you get too close then a good bit of the spray will drip down on your head, so don’t get too close. Be careful not to spray in areas that are open and get water inside the house. Also be careful not to spray windows if the pressure is very high. Never get on a ladder to reach high spots. It is much to dangerous to work with a pressure washer and try to balance on a ladder. Remember, this is extremely high pressure, so never point the nozzle at anyone and be sure to wear safety glasses. Of course, never spray water around electrical wires.