Roof cleaning starts with a sweeping and blowing off the roof to remove loose tree debris like pine needles, branches and leaves that can trap moisture and keep your roof surface damp. Trapped moisture on the roof makes it possible for moss to easily start growing on the roof and then that moss further traps more moisture close to the roof. Constant moisture can lead to bacteria and mold growth. This eventually can lead to holes in your roof and leaks into your home. Also, the root-like structures of moss and lichen can degrade the shingle surface and heavy moss can lift up shingle edges allowing water to get in where it never should. This increased risk of damage to the home has led many insurance companies to cancel Homeowner's Policies when an inspector finds moss on the roof. Roof cleaning as part of home maintenance can help prolong the life of your roof and protect your home from costly water damage from leaks or rotting roof structure.
What to look for in a Roof Cleaning Company
For moss removal make sure that you hire someone with the proper pesticide license from the Oregon Department of Agriculture. You can look up any company to see if they are licensed here: Search Pesticide Licenses. The Oregon EPA regularly audits roof cleaning companies and their service records. If an unlicensed roof cleaner has been performing work illegally, they can be fined $10,000 for each violation and clients who hired the unlicensed roof cleaning company can also be fined $10,000.
Never let anyone pressure wash your roof. Most roofing manufacturers will void your roof's warranty if it is pressure washed. Pressure washing degrades the roof surface and causes excessive wear and damage.
Make sure that the company is working safely to prevent falls. The products used to treat roof moss are extremely slippery and should not be attempted by an untrained homeowner. Anyone working on the roof should be using a safety rope and fall safety harness according to OSHA standards.
All moss treatment products are classified as pesticides and have the potential to be harmful to humans, pets and other vegetation. Protective gear including eye and skin protection and respirators should be worn whenever working with these products and the surrounding area should be protected to prevent harm to any other living organisms in the vicinity.