If I have reason to believe there is mold in the ductwork, we'll bring in a company that does duct cleaning with a biocide.It appears the mold in this house is limited to sheetrock and a couple pieces of subfloor, so hopefully it will be as easy as fixing the leak, cutting out the moldy sheetrock/subfloor and replacing it.

(roof- composition shingle on ranch, a/c heatpump needs to be installed with current duct work from furance, 1.5 jack and jill bath, kitchen, 2 bedrooms , its defiantly outdated!

i had one inspection on my first property...he said the attic door was too small for him to go through, and there wasn't enough room in the crawl space due to the ductwork....thanks jackass..350 bucks for him to tell me that a few outlets weren't grounded basically...

They tell me I need new duct work in the basement and also return vents.

They go to your air handler coils, and duct work. 

To convert a den to a room, you will add a closet, which will most likely require an addition and/or a relocation of light switches, outlets, and potentially ductwork for the HVAC. 

When the new HVAC system and duct work was installed, some of the joist bays were used as return ducts.

No duct work currently.  

I am considering replacing.Here is why:  Years ago I bought a home and replaced the furnace and all duct work etc.  

-I don't know about how the duct work is currently set up for ac/heating of this room.