Painting a house is a tough project, but the finished job can be quite rewarding.
After you've put any remaining paint away and sat down with a glass of tea to enjoy watching it dry to a beautiful new finish, you think to yourself how wonderful it is that you won't have to paint again for a number of years.
However, if you didn't pressure wash prior to painting, you'll be in for a pretty terrible surprise. Foregoing pressure washing prior to painting will leave residue in place that won't allow the paint to fully stick.
When chalky residues and dirt that weren't removed in the beginning start to come loose, they'll take the overlying paint off with it.