Perform the duct cleaning for the system, removed all of the supply air registers and clean each of the branch lines. Cleaned all of the registers and reinstalled them, removed all of the return air registers and clean each individual branch line. Cleaned all of the registers and reinstall them. Cleaned all of the main supply and return trunk line in the basement and the crawl space. Patched all holes and started the system up. There is a section of supplier duct which is 24x10 that is severely rotted and needs to be replaced, there's also a takeoff that feeds one branch that will need to be replaced and a takeoff of the bottom of the duct with another damper that is also rotted and will need to be replaced.