<p>If they power wash your house before they paint make sure they 1)use a very low pressure stream, 2) wait a least a full week of very dry weather before applying paint, and that you have enough money to repaint the house in about five years.<br>
I would never power wash a house, let alone before painting. The pressure drives water into the wood and it takes several months for it to come back out, even if it appears dry. If you put paint over moist wood, the paint will just peel off. Better to dry scrap loose paint and brush the house off. Only those parts of the house that are seriously dirty should be “washed” and even there a good brushing should take care of most of it.</p>