I’m never certain whether it is the result of lack of experience and knowledge or an intentional plan to provide a service of limited value.
Regardless, some Portland roof cleaning contractors continue to offer to treat roofs (most commonly cedar) with treatments that should be preceded by power washing. Don’t get me wrong; we prefer to clean cedar roofs with less invasive methods such as brushing and treating and to avoid power washing.
The key, however, is using the right roof treatments. Not every treatment that preserves wood or prevents moss growth has any cleaning capabilities by themselves. Our proprietary treatments do, but most other treatments require the roof to be previously cleaned. Copper and Zinc treatments are meant to be applied to a clean cedar roof only. They possess no ability to clean the roof. This would require power washing.
Yet, when faced with a homeowner who has done some research (maybe on our site!) and who states a preference not to have their roof power washed, some contractors will just offer the treating portion of the job. This results in all the dirt, pollutants and fungus just getting sealed right into the roof. This is very inappropriate and not beneficial to your roof.
So beware – if someone offers to simply treat your cedar roof, make sure it is with a treatment that possesses actual cleaning capabilities and is designed to be applied to a dirty roof, such as our sodium silicate based CedarGuard.