We do quite a bit of communal area cleaning, we price it at £15+vat per manhour and base the time on not only the cleaning time but the set up time and overall cleaners time away from base.
Our minimum price is 2 manhours, however, things you need to take in to account:
Neighbourhood and tenants, do they look like they look like they have any respect for the stairwell areas or are they just a dumping ground that you will need to be bottoming every time you go there. We have some that needed bottomed out the first time but now just pretty much need a dust and vacuum on a weekly basis
Frequency, weekly fornightly, monthly
What is required
Condition of the building and landlords expectations
Is there a storage cupboard for your cleaning equipment or do you need to bring it on site every time.
Travelling time
It will always be a case of "best guess" when pricing up this type of work, we have priced up work and been double the winning tender and won other work where we have been nearly half of the next best tender, as a general rule we make a decent profit from these jobs, some weeks the cleaners have it easy, other weeks they may come in to something requires a bit more time. Had one on Monday where someone had thrown a full tub of curry all over the walls, floors and windows!! Just got to get on and get it cleaned. In others we have tenants who actually clean and mop the floors on a daily basis so there's very little for our cleaners to do.