The best and simplest answer for this question is yearly or before and after the severe weather season in your climate (winter for northern areas, summer for southern areas)
A homeowner can perform an inspection from the ground with a pair of binoculars or during regular homeowner maintenance on the roof (more info here for completing a homeowner inspection). You can also find a local roofing contractor to come out and do an inspection for you.
Sometimes there are issues as homeowners we do not see that only a contractor might see. For example, the photo to the left had water from the gutter sit against the siding, which caused a leak. On this house the water was also running inside the wall, rotting not only the siding, as well as the wall studs, flooring, and ruining the insulation. The owners were unaware there was a problem going on for years. However, without a proper inspection, these issues are difficult to find.
Don’t hesitate to call for your inspection! It is best to know the exact conditions of your roof! Call us for your FREE inspection! 866-ROOFING or 360-652-4300.