Ok so I have recently took on 2 very large care homes on 4 weekly windows, a 90 bed and a 75 bed. The buildings have been unloved for 5 years been left empty since been built, some money issues with the development, anyhow the care firm that have now took this on want to clean it up, they have asked me about the cleaning of the render, huge job and not something I will prob end up doing, but what would be your approach to it and what would you use to clean it? I tried a small patch with Ubik 2000 and a WFP brush, let it dwell and scrubbed, but nothing came off. I was thinking Hypo ? Would this be ok going on to the windows which are all white Upvc, just been cleaned up. Plant/garden wise nothing to worry about really.