In my experience, contractors (most of them) take the easy/cheap way out. If you want it done right, you need someone who has your back, and that usually means a consulting engineer whose job it is to not only specify items like this, but make sure what is actually supplied meets the spec!

Building your own data center
 

PTS has an impressive track record for unique architectural and engineering designs. We specialize in all aspects of architectural as well as mechanical, electrical, and plumbing (MEP) and building services engineering for virtually every type of building.

http://pts-de.com/