The sheet metal frame in the floor (below where the air register sits) and the flex duct are ruined and must be replaced. The sheet metal in places is completly rusted through and crumbling. The floors are tile and hardwood. Some is acessible via the basement between the floor joists. Most is between the upstairs floor and the sheetrock ceiling downstairs. The house is about 13yrs old. The hvac units are all in good shape and working properly, so they arent an issue.

What is the easliest way to go to do this? Is there any way to avoid tearing out the sheetrock ceiling? Say perhaps pulling new duct through the opening. Thanks, thanks.