Alternatives to TSP for Exterior House Washing
TSP stands for trisodium phosphate, and is commonly used to prep surfaces before painting. TSP comes in powder form, which is mixed into warm water before application. TSP is a slightly toxic material, and while it cleans the surface of the walls, it is not always strong enough to eliminate all contaminants and mildew from exterior walls. Fortunately, there are many alternatives to TSP, most of which can be found right at home.
Pressure Washing
Pressure washing is the No. 1 alternative to using TSP on the exterior walls of a house. A pressure washer can blast off dirt, debris and loose paint that can easily prep a house for painting or refinishing. Pressure washers can be purchased at most home supply stores for around $100 or less, as of 2010. It is important to use the right setting on the pressure washer for the material that you have on your walls. Shingles and siding should be washed with less pressure than bricks or rock walls.
Detergent
A solution of 1/3 cup of powdered laundry detergent per gallon of water can be used to wash away grime and dirt that has not been ground into the side of the house. This cleaning solution will probably have to be followed with a mold and mildew cleaner if that is a problem on your home. Make sure to rinse away the detergent with plain water after washing the sides of the house or else the new paint will be unable to stick to the walls.
Bleach
Bleach is also a powerful alternative to TSP. Bleach can be used to bleach away stains, dark spots and can also protect the walls from further damage from bacteria and mold. Wipe a bleach solution of 1 quart of bleach per 1 gallon of water over the walls. Follow the bleach solution with a cleansing solution of detergent or some other cleaning method to remove the grime and dirt from the walls once they are disinfected.
Vinegar
A solution of 30 percent vinegar to 70 percent water can also be used to remove grime and dirt from the sides of a house. This method works best for vinyl siding, rather than brick, wood or shingles. Some other cleaning methods can damage vinyl siding; the vinegar provides a gentle and effective cleanser for vinyl that prepares the area for painting.
Window Washing Solution
Small spots of dirt or mildew can be removed with window washing solution. This method should only be used if you need to clean small portions of the wall, or if you do not intend to paint the walls afterward. The window washing solution will cleanse the area of dirt, tar and even mildew in some cases.
Powdered Cleaners
Powdered household cleaners, such as Comet, can be used to clean the exterior walls of a home as well. Mix 2/3 of a cup of powdered cleaner should with one gallon of water. The abrasive materials in the cleaner can help remove dirt and algae that has become ground into the surface of the walls. This method works best for brick or vinyl siding.