On a metal roof you can just brush it off or use a little pressure to sweep the lichen off. Generally you will know its dead once it turns white, at that point it will come off on its own in time.
This is not the case with other roofs though, anything other than metal you will want the lichen and moss to come off on their own which can take months.
To answer your question, the lichen is dead within minutes of its contact with the SH.

Thanks a million for that.

Nothing outside of telling her that if it has not come off than it is not ready to and when it is decomposed enough it will just fall right off. Taking it off now will just cause excess damage. We learned the hard way that it can take up to 6 months to fall off, and make sure to tell all customers that it can take from 3-6 months to come off.
Message me if you want regarding the BBB complaint.

I don't know if the cooler weather slows down the process.  Maybe the roof needs to be retreated because the lichen wasn't completely dead.  Did you stop by to see if the lichen turned white?

Hi Tim,

It is all white/dead . we are just hitting 3months of when I did the roof.

Hi Mike,

Thanks, I will try and talk to them about that. I was thinking of retreating the roof in March.

I tell everyone the same...3-6 months. Some people call after a few weeks and say its ot off yet. I remind them and they usually don't care. I did have be lady complain, so I told her I would remove it with medium pressure and a broom, if she would sign off that any leaks, damage, granular loss or anything wrong with the shingles after we finish,  am not responsible for. She said no and waited. It all came off in two months or so, and she called me and thanked me for the info.

Great to hear all this advice. I have also thought it might be a good idea to use low pressure a couple of months after treatment just to remove.... Maybe a good add on service if the customer is impatient

Zach Maynard wrote:

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Honestly Garon, when it comes to lichen and fiberglass shingles I think all the guys agree that this only applies to worst case scenarios. Making lemonade out of lemons is always a smart move but the potential to cause damage will always be a concern.

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ABSOLUTELY.  Sometimes it seems to be a delicate balance between pacifying a customer and possibly damaging their roof.  I agree whole-heartedly with the advice to have the customer sign a waiver which describes in detail what industry expectations are for lichens to release AND sign off on what the possible damage could be to their roof should they insist on having lichens or moss "forcibly removed" as opposed to weathering off safely.

The entire reason we service their roof is to END the damaging process caused by the infestation. The customer must completely understand that what they are requesting us to do is in direct conflict of what they contracted us to acheive.