Last weeks Ask This Old House episode had an item about sealing
heating ducts. They mentioned that you shouldnt use use Duck Tape to
do the sealing because the adhesive dries out after a few years. They
said to use metallic tape instead.
My question is, why doesnt the metallic tape adhesive dry out too? Is
it different from that used on Duck Tape?
I'm also wondering why I couldnt just use the tape used to seal the
joints in Tyvek house wrap. Its supposed to last many many years and
it sure is tenacious and sticks to anything.
There are thousands of types of adhesives for many different uses. Use the
one appropriate for your situation for best results. The Tyvek tape may or
may not hold up on sheet metal that is heated. Just don't bitch if it does
not work. I doubt an of us here know the proprietary formulations of the
different tapes to give you the definitive answer.
So sticky that it comes with a waxy paper backing that you remove prior to
using. Once it sticks, it's on to stay - even to itself. I found it
easiest to cut the piece the length needed, then start pealing just the end
of the tape. Stick that end straight and square, and with the rest of the
piece laying in place, peal the rest of the backing paper off as you press
the tape in place.
On Fri, 23 Nov 2007 14:36:47 -0500, email@example.com wrote:
Thanks for all your comments.
I have a bucket of the duct mastic too. I was going to use that on the
non-round, irregular duct joints.
I'll use the metal tape, but the roll of tape I bought is not called
HVAC tape or anything like that. Its just plain metal tape. Does that
make a difference?
I'm also going to do an easy to access joint with the Tyvek tape, just
as a test. If anyone's still around in a few years time, I'll report
My concern with Tyvek tape is, would it be a fire hazard?
I know I can put my hand on ducts and not burn myself, but, would you
like to explain to the insurace company that, because you were too
cheap to spend an extra quarter on a roll of tape that is designed for
the purpose of heat ducts vs combustable tape.
I can guarantee that duct tape does dry out and break down.
Mike Holmes on Homes (canadian show) talked about tape too. They were
repairing an issue with the heat not getting to the third floor.
10% of the heat was lost in joints alone!! do the monthly math...
worth the trip to the store and back.
Busting the drywalls reveiled that a pipe was disconnected and was
just blowing in the ceiling and walls.
Since i'm on it, they also added insulation around the ducts, which I
would love to do since my basement is not finished ... yet.
Use UL-181 approved tape only. The rubber backed duct tape of yesteryear is
no longer approved for flexible ducting. The UL-181 is a newer standard
that uses acceptable adhesives and is used by the manufacturer of flexible
ducting to connect collars. It is also advisable to use a "mechanical
restraint" on duct connections. A 48" zip tie is used today by the trades
to provide the mechanical restratint requirment. When ever you join two
pieces of flexible ducting, you must use a metal collar or sleeve to connect
them. Duct sealing mastic is also approved for flexibe ducting but it too
must have the UL-181 approval. Duct sealing mastic is designed to stay
flexible and expand as the ducts are warmed. Approved tapes also have a
none permeable [breathing] backing so the adhesives have a longer life than
those in rubber backed duct tape [cloth tapes.]
Through recent testing it is know that most residential air duct systems
have a leakage rate as high as 30%. By providing superior sealing you can
cut that to 6%.
I hope this is helpful.
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