It will make a difference especially if there are big gaps around bends etc, but whatever you do make sure that you dont use actual duct tape to do the job. Its not designed for ducts. Use mastic instead or even foil tape thats meant for ducts.

Any good hvac installer should be taping or caulking those ducts during construction as a matter of course. Watch your builder like a hawk and inspect everything, sounds like he will skimp every chance he gets.

thanks all...I was gonna go with foil tape only....but good points.

I would use a duct caulk as tape may come loose in the future and you will not know as it is in the wall.

for all your energy saving time well spent materials
www.hardcast.com
mastics like irongrip
tapes like 1402 mastic tapes.
these materials are UL tested and approved, accepted by
hvac industry. they expand and contract with temp differences and when correctly applied have a life of
30 years.

good for you!

good for you

I would use mastic and a chip brush to apply. I would seal all of the returns and supply vents. The time you waste will pay you back in $$$$ and comfort. The more you seal other things like pipe runs and where wires come up into the house and into the attic area the less air you will not waste time heating and cooling.

I would have to say for the average builder if you spent an extra $1,000.00 in sealants and time (yours or the builder's) it would probably pay itself back in less than 5yrs. This is talking going beyond what quite a few other builders do.

I have a quote in front of me for sealing things that I am doing myself after the 'builder thought it was a waste' home was built. If these things were done at the time of building it might have cost an extra weeks labor and less than $1,000.00 materials.

Seal returns in walls and floor joists $400.00
seal around baseboard trim (remove and reinstall and paint) on outside walls $3,000.00

wrap and seal supply ducts $1,840.00
Seal recessed lights $75ea x14
add one 6x30 return in hall wall $800.00

Doing this after the home is completed is a total pain in the rear compared to taking a little time and doing it at the time of the build.

It might seem to be a waste of his time or money but he isn't the one that will be paying the utilities. I would say from the sounds of this guy that you might be best to do some research on the net and ask us and others what to do and how to do it cause I doubt he cares to do it right.

Best of luck,

the bottom line is the installing contractor should seal ALL duct joints. In my area its code to seal ALL (longitudinal and transverse) duct joints with mastic and call for a partial inspection so the inspector can verify they are sealed before he lets you insulate the duct.
The "site supervisor" youre refering to sounds like an idiot. Leaky ducts waste energy.
I would keep an eye on the guy and watch out for any other things he may be cutting corners on.

thanks everyone.....I am gonna act as "hawk"...thanks for heads up

Were they 32years old eleven years ago? lol

Ditto the mastic. Much quicker. The aluminum HVAC tapes are good but they are slow in having to measure, cut, peel off the backing, etc. Mastic is much quicker. Wear gloves, use a brush in open spaces, smear it on by hand in tight places. Have extra gloves on hand to go back to brushing, etc. Especially seal any joints in the attic, and plan on later, after drywall is installed, to seal any penetrations made by ductwork between the attic and living space.