Sealing metal ductwork

[Bob Cooper]

Dust collection. I have always sealed all the seams of my metal ductwork. I'm wondering is its common or necessary. I cover each seam with AL tape. The straight runs are simple but the L's are a naturally a pain. Is this overkill?By the way I was apprehensive about using metal vs pvc but having done it I can't imagine doing it any other way. The flexibility of the L's is just so nice. Thanks

[Ben Rivel]

Yes you should. I am in the middle of setting up my first duct work system myself and from both Oneida and all the research Ive done you most definitely should be sealing all ductwork. From my research I plan to seal straight run snap lock along the seam with silicone, as well as 45 degree bends on their angles, then run proper aluminum ducting tape around all seams ensuring to cover completely at least three screws or rivets per union.

[Joe Jensen]

I read somewhere to use clear silicon because it was easy to remove if you reconfigure. That's what I did when I first installed my system and it was indeed pretty easy to rub the silicone off the duct with your finger, Also, the clear silicone disappears and it looks nice. Then I went and ran the wires for the auto gate system and taped them down with foil tape. Oh well :)

[Brian W Smith]

We use duct seal.All our dust collection tubes are painted.Custom hangars,sleeve and band connectors,blast gates are left,"in the white".We've rolled about 90% plus,all of the fittings...transitions,wyes,ells,etc.

Cheap flat "latex" paint on metal ducts.Provides that much more sealing(beyond duct seal).

[Ole Anderson]

Aluminum tape on the longitudinal seams and the easy joints, clear silicone on the bends and wyes.

[Jim Becker]

I use foil tape for sealing and yes, I use narrow pieces of the tape to seal up the elbows once they are adjusted to where they need to be. It does a good job and as long as the duct is held up steady, the foil tape will stay in place just fine. Many folks do use HVAC caulking for this purpose instead of the tape.

[Ben Rivel]

We use duct seal.All our dust collection tubes are painted.Custom hangars,sleeve and band connectors,blast gates are left,"in the white".We've rolled about 90% plus,all of the fittings...transitions,wyes,ells,etc.

Cheap flat "latex" paint on metal ducts.Provides that much more sealing(beyond duct seal).
Using duct sealant was something I was considering too. I didnt know if it was paintable or not. I was considering using this stuff: LINK (http://www.lowes.com/ProductDisplay?langId=-1&storeId=10151&catalogId=10051&productId=3736193&cId=detail)

[Bob Cooper]

Ok good. I've not really used silicone as it just seems like it would be somewhat messy but I do see where it could be easier to get into tight joints. In some areas I e used the fiber reinforced duct mastic and it sure seals well but as could imagine it's pretty permanent As far as undoing areas I've taped...that's not been difficult. I just finished reworking some sections and the tape was not too difficult to remove. Many times I want to keep the 90 anyway...just need to move it.

[Ben Rivel]

Ok good. I've not really used silicone as it just seems like it would be somewhat messy but I do see where it could be easier to get into tight joints. In some areas I e used the fiber reinforced duct mastic and it sure seals well but as could imagine it's pretty permanent As far as undoing areas I've taped...that's not been difficult. I just finished reworking some sections and the tape was not too difficult to remove. Many times I want to keep the 90 anyway...just need to move it.
Yea the sealant should only be used on pieces that will always be that shape or length. Im only doing 90 degree turns using two 90 degree adjustable elbows each in 45 degree orientation so they will always be used in the 45 degree setup and thus can be permanently sealed that way. Straight runs same thing. Those can be cut shorter if needed.

[John C Bush]

Duct sealer is inexpensive, easily applied with a brush, elbows, Y's, and other hard to reach connections are easy to seal, can be separated if reconfiguring, you can "touch up" leaks with the DC on if needed. Only negative is it isn't very pretty. I tried tape initially and the duct sealer is much easier to use-cheaper too.

[Daniel O'Neill]

FWIW you can paint the duct sealant. I've never had to but you should be able to break it apart if you want to reconfigure. Though I imagine it would still be a pain to do that.

[Jim Finn]

As a retired sheet metal worker I recommend the brush on duct sealant. I have even used it on the inside of duct where the outside was not accessible. I installed a six inch, metal, dust collection system in my small wood working shop.

[Ken Fitzgerald]

I used aluminum foil tape and it's held up for years.

[Tom M King]

If you know you're going to move some of it at some point, this stuff works great. On our jobs, the setup might be for a year or two sometimes, and this comes right off leaving no residue, but still seals the ductwork just fine. I think they claim three months or something outside with no residue, but I have only used it inside. I sealed the ductwork with the real aluminum duct tape once, and it was more than a royal pain to get off.
http://www.amazon.com/Scotch-Painters-Clean-Removal-Outdoor/dp/B0067NLZOE?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o07_s00

[Clay Crocker]

Foil tape works well for me. I use full width tape on straight joints and cut the tape down to 1/2 width for taping the elbow joints. If you ever need to reorient an elbow, you can just slice the tape at the joint seam with a box cutter around the entire circumference, twist the elbow joint to the new orientation, and then just re-tape over the old tape.

[mike mcilroy]

Foil tape works well for me. I use full width tape on straight joints and cut the tape down to 1/2 width for taping the elbow joints. If you ever need to reorient an elbow, you can just slice the tape at the joint seam with a box cutter around the entire circumference, twist the elbow joint to the new orientation, and then just re-tape over the old tape.
Clay is right, I've done it a few times now as I learned permanent doesn't exist in my workshop.