Sealing heating ducts

[dicko]

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.

-dickm

[Edwin Pawlowski]

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.

[J.A. Michel]

Metal tape is VERY sticky, and has the added benefit of crimping and crunching down on small openings. It's what you should use on ducts.

[scott21230]

Don't use duct Tape, it's crap. The metal HVAC tape mentioned about is what you should use yes.

[Red Green]

dicko wrote in news: [e-mail]:

Different tape material and glues.

You could. You could also use $1 a roll Mainstays clear tape from Wal- Mart. Tyvek house wrap is for Tyvek.

On Tyvek I bet you're right.

For some period of time, I bet you're right...day, week, month, year, years.

See

[HVAC tab] for proper stuff for your application.

[J.A. Michel]

Did you read my post? I agree, metal tape is what should be used.

[gfretwell]

Check with your utility. Some will subsidize a professional "mastic" job or just pay for it outright. That is a lot better than any tape.

[dicko]

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 back :-)

-dickm

[cln]

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. cln

[Zyp]

Dicko;

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.

[dicko]

Thanks, It helped a lot. The roll of metallic tape that I have does not mention UL-181 anywhere on the package. I'm going back to the store to search for a roll that is UL listed.

-dickm

[Mark]

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.

[CJT]

Get the UL listed stuff.

[CJT]

It won't be cheap, but you'll be glad you did.

[cln]

I was at an open house and noticed the duct sealing mastic. Which would be better, tape or mastic? Price or other comparisons appreciated?

cln

[cln]

Here is an interesting PDF with facts on heating ducts