In areas with moderate humidity you are likely to find that the north side of your home or maybe more areas have moss or mold buildup. Not only can this be a visual problem but over time the buildup will cause breakdown of your shingles and it could lead to some serious damage.
The best way to take care of this problem is to do general maintenance on your home yearly. You don’t want this problem to get away from you or you will end up with a buildup that is difficult to rinse off and then you risk damaging the shingles by removing the gravel surface.
Using a pressure washer on shingles is a bad idea. Even using a normal garden hose at a close distance at a high pressure will damage your shingles.
To kill the organic material you want to use bleach diluted in water. You can apply this with a garden sprayer or in some instances you can use a pressure washer with a soap additive adapter to shoot it up onto your roof or siding from a distance. However never apply it with high pressure.
How To Prevent Moss and Mold Buildup on Your Roof
Some roofing companies may suggest that you install zinc plates across your roofline to prevent organic growth. This may help in some areas where the growth of material is relatively mild but it probably won’t work in very high humidity areas that see long hot days and lots of moisture.
If you live in an area like Florida, Hawaii, Washington State or similar areas then treating your roof will be a yearly job.
Final Note
This is one project that I talk about a lot because many people have this problem. The cure is inexpensive it just takes half a day in the spring to apply the bleach solution. If you are older or just don’t have the ability to do the work yourself then any general handyman should be able to do this for you.