If you still hear them too much, a laminate floor up there floated over an acoustic pad/membrane may further separate the surfaces transferring sound.

After installing the cement boards and taping them and all that jazz I ended up using a waterproofing membrane which was considered optional. 

Sam:The aluminium pigmented coating on the rooftop is primarily aimed at protecting the roof membrane itself with reduction of thermal loading in the building being secondary.  

I am not convinced as to the longevity of copper vs. membrane shower pan, that's a tough call.Also, do not skimp on a cheap stamped steel tub.

concrete backer board is one way to go or you could use DITRA the orange membrane that goes underneath tile and is a great product.

All you do is collect a check whether it's to pay off your debt and keep in your bank account..Some office buildings if it is occupied by one big tenant may have Absolute NNN where the tenant is responsible for tax insurance and maintenance as well as structure and roof membrane of building..I am not too familiar of Office Buildings in terms of force appreciation but Multi family apartments offer that strategy..Hope this helps Good luck

The biggest thing is to make sure that it is sloped properly and all the flashing and roof membrane is in good condition.

Last seller purchased for $389,000 and had to do extensive excavations/renovations to waterproof the basement/added tank, added commercial gutters, waterproofing membrane, etc.

And, modern flat roof systems consist of a membrane to waterproof the roof and not the layered felt & hot asphalt.  

If you're worried about cracking, use a crack-isolating membrane like Kerdi.