Got my first commercial job to look at in London. They want specialist clean of self coloured render and a treatment to prevent further staining. I was thinking a trolley system with pole and chemical. Anybody got any advise on techniques , how to price and what the best chemical would be? The price will be for the whole building but I need to confirm this. These pictures are from streetview and will be visiting the site over the weekend. There are 3 blocks of flats.