Over time, the roof and siding of your garden shed can get covered in a thin layer of moss that reduces the visual appeal of the structure. This can especially occur if the shed spends much of the day in the shade. The solution isn't to redo the roof or siding. Instead, you can rent a pressure washer and restore the original appearance of the shed. Although some scrubbing with a stiff-bristled brush may be necessary if the moss is especially thick in certain areas, you'll generally be able to remove much of the mossy layer just with the pressure washer, which will greatly improve the ease of removing the moss. Here are some steps to take to get the job done right.
Begin with the Roof
Ideally, you can use a ladder to climb up onto the shed roof. This will give you a perfect spot for positioning the pressure washer's spray in the best way possible. The key is to stand at the peak of the roof and clean one side of the roof at a time. It's critical to focus the spray on the top level of shingles and then gradually work your way down to the edge of the roof. The spray should always be pointed toward the bottom edge of the roof; if you were to clean from the bottom up, for example, the pressure washer would push water beneath the shingles, and this could end up rotting the plywood sheathing below.
Move to the Siding
When you've cleaned the roof to your satisfaction, it's time to focus on the siding. Always start at the top of the siding and work your way down; like with the roof, you should make sure that your pressure washer is positioned in such a way that the spray doesn't shoot up beneath the individual siding panels. For this reason, it's a good idea to stand on a ladder so that you'll always be spraying at a downward angle.
Deal with Stubborn Areas
If you've given the entire shed a spraying but there are still stubborn areas—such as areas where the moss has stained the siding—switch to the pressure washer's brush attachment. With this attachment in place, you can direct a powerful spray of water at these mossy areas and scrub at the same time. This is often enough to dislodge any remaining particles of moss and restore the look of the shed. If you're having trouble getting the end result that you desire, consider hiring a cleaning service to finish the job.