Roof Cleaning method 2.

The chlorine-bleach roof cleaning method

Roof cleaning contractors who use sodium hypochlorite (chlorine bleach) mix it in high concentrations with other chemicals such as trisodium phosphate, also known as TSP. 

They spray it on the roof and wait for it to dry and then re-apply it several times as needed. Stains and moss or lichens that don’t come off on the day of treatment may eventually come off with rain in the months to come. 

Pros: The bleach method can be less expensive than other methods because the chemicals are inexpensive and the technicians generally don’t get on the roof to rinse or inspect after the application. 

Cons: Strong chemical odor and results that may not be instant, particularly when moss and lichen colonies are involved. There is also a possibility of posing harm to people and pets if exposed to the fumes or fluids. The effects of bleach on landscaping can cause permanent damage to plants, trees, grass and shrubs. Contaminating bleach and phosphates can leak into waterways in watershed areas.

Tip: Roof cleaning contractors who use chlorine-bleach typically don’t advertise or divulge that they use bleach. If they need to wet down plants before, during, or after treatment or use a runoff recovery system or cover plants during the roof cleaning process, these are indicators that a harsh chemical such as chlorine bleach is being used.