[TomCrowther]

Hi All, I hope you can help with this question re mossy walls.
I do a variety of cleaning services and have just been asked to "overhaul" a small block of flats, 20 apartments in total, five floor building. It has been unmaintained for years and the gutters have been blocked for ages, water spilling over down the face of the building. The results aren't pretty and areas of the walls are covered in moss as a result.
I think the first job is to clear and repair the gutters which should be fairly simple {apart from the height}. The moss is in a number of large patches, some right up near the roof level, some lower down. If I powerwash the moss off the walls, am I likely to be left with patchy walls? Should I powerwash the whole wall area in order to achieve a decent result? The bricks are a light colour which I think will make the clean areas stand out more once done.
Also, would hot water make the job easier?
Cheers for any replies, Tom.

[Blast Away]

You may find there's a light inconspicuous growth of algae which has accumulated from surrounding trees so yes the area would stand out.
Hot water would be a waste of fuel in this case. Cold water will do the job, if done thoroughly as when dry you may find stripes. Fan lance to prevent damage.

[TomCrowther]

Thanks Blast Away. Would you treat it before pressure washing? And would you offer to seal the wall after or is that something that is not normally part of your routine? Many thanks.

[Matt Gibson]

Sealing wont stop the moss growing back, but if you fix the gutters etc, then it will never get as bad as it has done.