I clean the office windows for a local warehouse, the owner has now asked me to clean the main warehouse building once a year top to bottom. Its roughly 50m across the front, 100m long and 35-40ft high.. I have no idea on prices charged for this kind of work can anyone help? I want a price for job not an hourly or day rate please. I dont want to over charge nor do I want to lose out. Cheers Dave.