When duct-work is installed at the rough in stage, a contractor will usually try to be as efficient as possible with the ducts and do his best to minimize ducts that stick outside of walls and ceilings. A less experienced tradesperson can needlessly ruin a ceiling in the home where there could have been a solution for the ducts popping out. Our contractor goes a step further to minimize bulkheads: exterior wall ducts. Normally, ducts are not installed inside exterior walls, as the walls are always insulated, so there is no room for a duct. This problem is solved by insulating and sealing the space between the studs in such a way as to retain proper r-value, while also accommodating a duct.
We like clean walls and ceilings without unsightly boxes sticking out of them. Yet another trick from our million dollar homes. Hidden accomplishments such as these make us have a very nice feeling inside.