Contractor Talk - Professional Construction and Remodeling Forum banner

duct taping your joints

15K views 14 replies 12 participants last post by  able14 
#1 ·
I recently built a house, the Hvac was all installed and I was wandering if you should duct tape all your metal duct joints and little holes where air can seep out. My installer says no, but doesn't make sense to lose warm/cold air in crawlspace/attic.
 
#3 ·
Was the IRC the code document that covered this job? If so, here you go:

M1601.3 Installation.
Duct installation shall comply with Sections
M1601.3.1 through M1601.3.6.
M1601.3.1 Joints and seams.

Joints of duct systems shall be made substantially airtight by means of tapes, mastics, gasketing or other approved closure systems. Closure systems used with rigid fibrous glass ducts shall comply with UL 181A and shall be marked ia181A-Pla for pressure-sensitive tape, ia181A-Mli for mastic or ir181A-Hli for heat-sensitive tape. Closure systems used with flexible air ducts and flexible air connectors shall comply with UL 181B and shall be marked ia181B-FXlv for pressure-sensitive tape or ia181B-Mls for mastic. Duct connections to flanges of air distribution system equipment or sheet metal fittings shall be mechanically fastened. Crimp joints for round ducts shall have a contact lap of at least 1.5 inches (38 mm) and shall be mechanically fastened by means of at least three sheet metal screws or rivets equally spaced around the joint.
 
#11 ·
Was the IRC the code document that covered this job? If so, here you go:

Crimp joints for round ducts shall have a contact lap of at least 1.5 inches (38 mm) and shall be mechanically fastened by means of at least three sheet metal screws or rivets equally spaced around the joint.
what do you mean with 3 screws? Can anyone else confirm this?

See above quoted code...
 
#5 ·
I always tape my joints. I only use metal tape. If it is not available I use "pooky" aka duct sealer. I do not use pooky all the time due to the fact that it takes the neatness out of the install but it works just as well. I do not think it will make a world of difference but I would go ahead and do it anyway it shouldnt harm it unless he is making up for something else that is not right. I have seen contractors leave spaces open on purpose if they have over sized the unit, do not know how to set it up or the blower size is too small to push the heat out fast enough before it goes off on limit. Good luck.
 
#6 ·
Same here. On new installs alwys tape the joints. Only if it's an old house upgrading to a new service where you might want a bit of seepage. But you mentioned a crawl space and an attic. Not the kinds of places you want to crawl back into if you think you're done the job.
 
#12 ·
thanks dustball-I had in my head a previous poster was referring to fibrous ductboard, in which case 3 screws didn't make a lot of sense.

when he says ducttape, is he not referring to the metal ducttape but the 'duck tape'?

When applying metallic ducttape to fibrous ductboard, do you clean the surface first (at all or w/ a particular cleaner)?
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top