tombijak

Scott, thanks for reply, but I'm still searching for definitive IRC code citation/interpretation that prohibits flexduct thru floor/ceiling assembly penetrations in residential construction. I'm beginning think that my city's code enforcement dept. is confusing firestopping with fireblocking where the former applies to rated assemblies and the latter to non-rated typical residential construction. Clearly, flexduct is not permitted thru a fire-rated assembly as in commercial construction or in residential multi-family. I have not, however, found a clear prohibition in IRC that prohibits flexduct in passing thru floor-to-ceiling or wall-to-soffit penetrations.

Aug-04 edition of the "Journal of Light Construction" has a good how-to artical on sealing up/conditioning a wet crawl space. I've not done one myself, but I am intrigued by the idea.

Where specifically in IRC (2000 I presume) does the code exclude Flex Duct for floor-ceiling penetrations? I've read "Chapter 16 Duct Systems" several times as well as the referenced section "R602.8 Fireblocking" and cannot find an exclusion. In order to use ducts in the first place, they must be Class 0 or 1-- which the flexducts are. Regarding thru the floor/ceiling penetrationos, fireblocking around ducts requires approved materials (R602.8, 4.). Is there another code that applies to Residential (single family dwellings) that specifically excludes use of Class 0/1 rated flexduct for floor/ceiling penetrations? Thanks in advance.