Cleaning lichen from long run Roof

[TheLibrary]

Need to engage a someone to clean the roof which has quite a bit of lichen on it, but first am seeking some advice on this forum about the process I should agree to. Is there a preferred method? I see some info on certain sprays and chemicals being used, but are they bad for the roof in the long term. What about water blasting?

More interested in getting it done correctly than the cost.

Thanks in advance.

[artemis]

We use Chemwash for all exterior cleaning including roofs. May not be in your area but they have a lot of information on their website about their processes and products used. For lichen and similar they have a spray and leave process, kills the spores and they blow away over time. They also give a service warranty that we have used a couple of times (over many years and many jobs) where a few roof spots were missed. Quickly remedied.

[heugumper]

I have applied two products myself, as different jobs, a cheap brand moss and mould killer and a more expensive one from wet & forget. Both worked well, equally slow on lichen, I missed parts each time and had to return. Can be hard to reach everywhere.

Roofer contact suggested against water blaster, due to risk of damage and forcing water into the roof cavity. Also, above method avoided walking on the roof.

I have recently paid for a company to redo one roof, six years later. Low pressure, no walking, etc. Too early to tell the results.

[TheLibrary]

Thank you both. Very helpful advice to move foward.

[Buzzair]

I've used Edwards & Hardy for many years - 100% recommended. Slow acting over a few months and well priced. They guarantee their work.