Telephone building renovation and remodel

I own a commercial building with a 2,000 sq/ft private residence penthouse on top and would like to renovate the inside and buildout a new master bedroom suite on top of an existing lobby in the commercial part of the building. The addition would add an additional 1,000 -4,000sq ft or so also installing an elevator that would access the private residence and also the rooftop. There’s an existing small ADA compliant elevator/lift that already exists but does not access the private residence or roof top currently. I would also like to structurally engineer the rooftop to be a one of kind outdoor entertaining space with a rooftop kitchen, hot tub, gas fire pits, and a shallow but expansive reflection pool. Again, one of kind.