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.
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