# foil tape vs. duct tape for ducting



## amakarevic (Apr 12, 2007)

are the two pretty much interchangeable or are there specific uses for each kind ?


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## nap (Dec 4, 2007)

duct tape is crap for taping ducts.

Foil tape or mastic (a gooey substance used to seal ducts) is what should be used. The foil tape has limitations. It does not stretch and as such, is limited to what it will seal. Mastic can be messy but does the best job, as far as I am concerned, if applied properly.

in fact, duct tape was not made to be used on ducts. It was invented during WWII by the military to seal ammo boxes. California specifically does not allow it's use on ducts. I understand some other states feel the same way.


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## amakarevic (Apr 12, 2007)

wow, not just an answer but also a history lesson  thanks, dude !


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## beenthere (Oct 11, 2008)

As above. Duct tape is NOT for use on duct work.


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## ptarmigan61 (Aug 19, 2008)

Actually, as I understand it, it was originally duck tape becaue the tape was made with a canvas 'duck' cloth base. Duct tape as a name evolved with usage.


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## nap (Dec 4, 2007)

just call it 200 mph racer tape (that would be something like 322 kph for you in the Great White North)


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## yuri (Nov 29, 2008)

Right on. we'll get you converted yet. :thumbsup: Foil tape is high temperature resistant (to a point) and is sometimes used to seal air leaks on ducts better than duck tape as the glue in the duck dries out after a year and it falls off. The foil tape is on for many years and sometimes permanently. Plus wannabe tin bashers like myself can do a airtight installation much better. Mastic, especially the red duro dyne will get you really stoned in a hurry in an attic. Good for burning out unwanted brain cells.:w00t:


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## plummen (Jan 10, 2010)

the inspectors around here are really pushing the sealing anything and everything around here,even if it doesnt leak.
We have to use the aluminum tape with ul181 stamped all over it,that mastic stuff is just nasty looking slopped on a new furnace/ductwork :laughing:


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## nap (Dec 4, 2007)

plummen said:


> the inspectors around here are really pushing the sealing anything and everything around here,even if it doesnt leak.
> We have to use the aluminum tape with ul181 stamped all over it,that mastic stuff is just nasty looking slopped on a new furnace/ductwork :laughing:


but it does an excellent job if applied properly. It will seal areas that are difficult to get the tape to conform to.

and no cuts from the sharp edge of the tape:laughing:


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## beenthere (Oct 11, 2008)

Use masking tape just like you wood if you were painting trim and didn't want to get any paint on the wall.
Makes it look much better.


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## plummen (Jan 10, 2010)

thats the problem most of the guys around here slop it on like theyre painting a fence! :laughing:


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## Affordable7 (Mar 5, 2010)

Foil tape has 2 different ratings as well. The red lettered foil is code for crawl spaces...etc..where extreme variations in unheated spaces occur. If you use the regular foil tape an astute inspector will fail the job. Mastic best for permanent code complying seal....especially California's .5% loss law.


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## drtbk4ever (Dec 29, 2008)

nap said:


> just call it 200 mph racer tape (that would be something like 322 kph for you in the Great White North)


Do you mean like in an application shown below?

you gotta love the red racing stripe on the RHS of the roof/trunk. Nice use of Red Duct Tape.


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