if you have a wfp trolley, fill it full of pure water or even tap water and put in a solution of Swift & Sure safe algae remover , this when applied will loosen the algae and just glyde off without problem and most other dirt, if the soffits or facias have ingrained carbonised staining then this will be a lot harder to clean and when they in this state, they are probably very old, so a solvent based cleaner would have to be used by hand, which is more difficult what with health & safety rules.
Black mould is one of the worst fungi,s for spreading rapidly, this is normally found at whiskey bonded wharehouses , this why these building are normally in the sticks and not in a built up area, for instance, I was called by a company to advise on removal of black mould near Bathgate in Scotland, the company wanted to erect more buildings on site and they had an issue with the local council planners, of fear of black mould spreading to nearby residential areas. I arrived on site and used the wfp system on a 3mtr section of guttering, the pure water was working but very slow , so i used the trolly eyetem with the swift & sure mix and it slid off the guttering and facias very easy, this was a test case to see if the company could control black mould before being allowed to build new units on site. I went back 6 moths later and there was no sign of growth on the areas we had cleaned, hence permission was granted.
I f anyone out there cleans exterior of caravans especially in wooded areas this is an ideal product for the safe removal of green algae.
If you require futher info on this subject you can contaxct me on 07771523669
