Are you going to beef out the exterior walls to make room for more insulation? 

New AC, Insulation vacuumed out and replaced. remodeled the bathrooms, new tiled shower surrounds and fixtures, .

Again, if you don't follow some simple rules on how to manage each LLC you may pierce the veil and lost the insulation between entities that you wanted, so it's not bullet proof but could be pretty solid if you do it properly.

Hello BiggerPockets Community,I'm embarking on an exciting journey to acquire and renovate a duplex from 1900, aiming to tackle the inherent challenges of outdated insulation and the lack of modern vapor and air barriers.

A few things to watch out for when buying homes this age would be electrical, insulation, sewer and plumbing.

Sandblasted the storm windows > foam backer > insulation > then cement board right over it for tiling. 

Is floor insulation required? 

It takes into account what size and type of windows you have, where the windows are located, insulation in the walls and ceiling, the type of construction etc.

I am about to add a shell in Dubai to further insulate and add more protection.   

Well-insulated walls cut down on noise.