Power Washing Your House

The Importance of Power-Washing Your House Prior To Painting

The best quality paint is only as good as the surface to which it is applied.  A clean, sound surface is essential for proper paint adhesion.  Paint applied over a dirty or contaminated surface is likely to fail in the future.

Besides normal dirt buildup, three forms of surface contamination may exist which are not readily apparent.

Salt Deposits

Eaves and protected areas of your home are susceptible to condensation and deposits of salt.  These salts are the result of water-soluble chemicals in previous paint films being drawn to the surface by moisture.  When the moisture evaporates, the chemicals are left on the surface in a crystalline form.  If not washed away prior to painting, these salts can attract moisture.  When temperatures dip below freezing, the moisture in the salt freezes and expands causing the new paint to peel.


After many years on a surface, a paint film breaks down to a powdery substance called chalk.  Heavy accumulations of chalk prevent proper paint adhesion and should be removed prior to painting.  If you wipe a gloved hand over a surface and chalk dust covers your entire hand, the chalk should be removed before painting.


Mildew is a fungus carried by the wind that can attack any painted surface.  Left unchecked, mildew can discolor and even destroy the paint film.  If painted over without treatment, mildew will often grow through the new coat of paint.  Mildewed areas should be treated with a solution of hypochlorite-type household bleach before painting.  Unfortunately, mildew can only be controlled since there is no known method of eliminating the return of mildew to any painted surface.

To effectively clean your house prior to painting, we use an industrial pressure washer.  This machine dispenses 4-5 gallons of water per minute at pressures up to 3,000 pounds per square inch.  Chemicals can be introduced into the water stream for the treatment of areas affected by mildew.  After pressure washing, your house will be free of any surface contamination that could jeopardize the longevity of the new paint job.

The information in this report was drawn from the following sources:

1)  Sherwin-Williams, “House Paint Inspection Manual”
2)  National Decorating Products Association, “Paint Problems Solver”
3)  Glidden Paints, “How to Control Mildew”