Duct Taping Your Joints

Travis

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.

JPF

Every ducting i've seen, there is the metallic duct tape at all the joints and seams.....i can't think of a reason you can't do it yourself, if you think it requires it.

mdshunk

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.

snapperhead

might want to get a gallon can of the commercial duct sealant they use and just brush it around the joints and holes (with the fan off till it cures)cures supper hard!stay away from just the plain duct tape,use aluminum or the same with a fiber in it...will last forever

FemaleAstarCO

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.

Hurley

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.

acefurnacefxr

In our area it is code, tape first then 3 screws..........in that order.

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Same Old

I understand you CANNOT use "duct" tape per IRC. You must use the metallic tape.

acefurnacefxr

Duct tape is accepted here.....

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72chevy4x4

what do you mean with 3 screws? Can anyone else confirm this?

Dustball

See above quoted code...

72chevy4x4

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)?

acefurnacefxr

Cleaning is not normally needed, but if the product is cold, its acceptable to heat it up with a heat gun slightly first, before applying the tape. Then a squiggie (spelling*?) is used to flaten out the tape and remve air bubbles.

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PrecisionFloors

When I say the title to this thread I just had to respond....



Don't that taste like ****?
sorry couldn't help myself.

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able14

Im with snapper head use foil tape or duct sealer is the duct insulated if not I would wrap it first