I think the other theory is you're better not to clean it. If you clean off the muck then it leaves gaps which leak.
Moss holding my roof together? Sounds about right. Just going to brush the single storey bits and get a guy to clean the gutters. Quite a few plants growing up there.
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I think the other theory is you're better not to clean it. If you clean off the muck then it leaves gaps which leak.