I'm delighted to find a forum with a section dedicated to roof cleaning at last!
I've been reading the old posts for a while, and I'm learning loads already.
My name is Nathanael, born in the UK, and living in Ireland for the last 18 years. I own and operate a contract cleaning company, and at the moment 90% of my business is window cleaning, 10% pressure washing.
I've been asked a few times by existing clients if I could clean their roof,... and my only option so far has been to use a roof ladder (Roofs in Ireland are generally quite steeply pitched) and climb up on the roof with a pressure washer.
Before you start to panic, we don't have shingle or asphalt roofs here. We have a fairly even mix of concrete tile, natural slate, composite (fibre cement) fake slate, and occasionally a fired clay tiled roof.
The pressure washer doesn't do any visible damage once the right tip is used, but I'm still not comfortable using it, and neither am I comfortable climbing up a roof ladder over slippery tiles with a heavy pressure hose pulling me down!
So I've been searching for an alternative.
I've read so much advertising & promotional blurb from makers of "Roof Reviver" type products about the damage that bleach can do to a roof, that I'm quite surprised to see how widely used it is by contractors here!
So,.. my questions are:
1: Can chlorine based cleaning damage or discolour slate/concrete tile/clay roofing, or is it all just hype?
2: How do you apply your cleaning "solution" to the roof? eg. stand on the ground and spray it up?
3: Do you need to scrub it,.. or is it a case of leaving it to work and simply rinsing it away?
4: Does your cleaning solution require you wear protective clothing, and does it do any damage to plant's etc where there's accidental overspray?
5: What is "apple sauce"??? I understand the Chlorine & tsp,.. but apple sauce is what I put on my roast pork normally!

Is there a generic, possibly internationally recognised alternative?
OK,.. I've more questions, but this post is long enough already, and I have to go to work!!!
Thanks in advance for the replies!