question about quarterly deep cleaning at office bldg
I do a 20,000 sq ft office bldg weekly, just a really basic floors/garbages/kitchen/baths clean with light dusting for spiderwebs and some glass doors. They have expressed interest in having a quarterly deeper cleaning done, where we would dust all office furniture and cubicle tops, wipe doorframes and baseboards, clean interior glass, and generally get all the details we can't do every week. Has anyone done this and what percentage of their usual fee do you charge? I do residential, as well, and if I do a deep clean at a repeat customer's house I usually plan on it costing 200-250% of a regular clean, would that be a fair price for an office deep cleaning? Thanks for input, they are a really great client (always pay bill within 2 days, forget net 30) and I don't want to put them off by quoting something that's way too high, but I don't want to get ripped off either!