Owning a home for several years should require at some point painting the exterior, normally now most reputable exterior paints hold up even through extreme conditions for more than 15 years, if preparations are done correctly no matter what time of the year exterior painting is accomplished.
Here in Denver Colorado is no different than most other parts of the country, in that exterior surfaces collect dust, debris, not usually seen with the naked eye. This is why it is imperative to power wash, cleaning substrate, giving fresh new paint a clean surface to bond. If pressure washing is not done, fresh new paint will trap dirt and grime underneath, impairing the paint's life and duration. In the painting industry, pressure cleaning is referred to as giving the painter a clean canvas to work with; comparing to Van Go.