How Often Should You Pressure Wash Your Home's Exterior?

Most driveways, walkways and siding benefit from a pressure wash once a year — twice if your home sits under heavy tree cover or gets a lot of shade, both of which encourage algae and mildew to take hold faster.

The giveaway signs are easy to spot once you know to look: dark streaking on siding, a greenish tint on concrete in shaded spots, and a driveway that looks noticeably lighter right after it rains and dries. Any of those means grime has built up past what a hose can fix.

Technique matters as much as timing. Different surfaces need different pressure and nozzle settings — too much on old mortar or painted siding can do more damage than the dirt ever would. That is the main reason to hire it out rather than rent equipment for a once-a-year job.