Indiana code for smoke detectors in rentals?

[Tricia O'Brien]

Hello!  One of my rentals has 11-foot-high ceilings in all the rooms except the kitchen, and a new handyman told me yesterday the smoke detectors are in the wrong location.  I have  6 smoke alarms on the main floor and one in the unfinished basement.  All of them are currently placed on walls at 8 feet off the floor except the kitchen one.  The handyman is recommending they should be moved up about 2.5 feet to within 10 inches of the ceiling to be up to code.   He is saying, at the place they are now, there would have to be 3 feet of smoke in a room before the detector goes off.

Does anyone know if this is correct?  I think it makes sense, but I also think if the detectors are that high off the floor, tenants are less likely to change the batteries when they go bad. 

What is the minimum number of smoke detectors required and do they need to be in every bedroom? Or just 1 detector per each floor of finished living space? 

Any replies would be appreciated! Thanks :)