yes by all means make sure he runs actual ducts and not even just span them with metal. If you dont, the return air will coming also from uncondtioned air in the walls and worse from any attic spaces. This will increase the load on your hvac and decrease the efficiency. while you are at it see if they will do a proper airsealing package and not just insulation.

Since you mention stud bays and sheet rock without more info provided, I am guessing your system will be in a semi-conditioned basement?

In that case, a good installer and homebuilder that follow his work will assure that the holes, risers and plates are sealed.

It is extremely rare that full sheet metal is run for returns with exception to the main return trunk that runs perpendicular to the joists.

I fact the only time I have seen such a house with full ductwork was when I sick person need better system hygienic and cleaning capabilities.

If your application is a attic, unconditioned space such as a crawlspace, thatÂs different and changes things abit.

Thank you. I'll provide a little more info. We are in Syracuse NY. The house will have spay foam insulation. Half of the basement will be finished, the other half unfinished. The unfinished half (where the furnace will be)will be insulated and should be pretty close to the finished portion in terms of temp and humidity.

My goal is to make this house as tight and efficient as possible. I expect that any holes drilled and the openings around risers will be sealed. The sheetrock will be screwed and glued to the studs. If we dont do ducts for the returns I will have him caulk or spay foam around the return vents. What do you think of that as an alternative to ducted returns?

As long as the top plates are sealed and better yet the builder or installer blocks above where he plans on cutting return registers, you will be fine.

ItÂs the fire code that will help you on the dead ending of the return cavities to prevent flame spread

A little bit of infiltration as long as it is not blowing by a water pipe is not a bad thing.

BTW, your going for tight but then you will be adding an HRV for fresh air right?

By your original post, I figured you were in the north, Go Orange!

I've always preferred ducted returns. Using building cavities can develop large resistance to flow, and there is a great potential for inleakage when joist bays are used; there's usually construction debris present, which can present Air Quality issues (also on that topic, the wood supports mold growth when wetted).

All well and good but, it is rare residentially in the north to duct the drops and how would the returns get wet?

Besides using the cavities is just the opposite of what you are saying Ferd, as the potential for larger returns is there versus stuffing a wall stack with turns in the studs, and boots for the return trunk.

Leakage in the north is not such a bad thing in the right places. Leakage in the north as it is located in a basement that tends to be used or even finished as living space is not such a bad thing. Time and time again there was such an effort to seal up the ducts in the basement area, only to turn around and cut registers and diffusers in the ducts in the areas that were just sealed to deliver conditioned air to the space.

Just had one where the contractor was afraid to cut the plate the full width of the stud space three places in each of eight townhouses, and I see that a lot; this guy left a half inch of plate all around the openings, and he'd been doing that for the five or six years he'd been in busuiness - possibly that creates a restriction to flow.

Never mentioned wall stack: I prefer bringing ducts into corners of closets and boxing them in; I've also had great success with ducted floor returns, even where floor supplies are used.

I'm not one for "return in every room" either (unless the AHJ can't be persuaded otherwise): Central returns are a valid way to reduce installed cost, something with which everyone's concerned these days; it also reduces pressure drop on the return side, which is a major problem with the work I see (it's quite common here to find more than half of the air pressure drop on the return side).

It's rare to see a basement here, crawl spaces with dirt floors are the norm; you have a valid point where there's a full finished basement.

Having plenty of experience with central NY HVAC installs, central returns are not acceptable unless for AC only on a hydronic home. Returns are the norm in every room except kitchens and baths and the airflow is made up in common areas and hallways.

Now being in Texas, what's up with these "jumper grills"? (Bedrooms tied to common areas via flex duct and two ceiling grills on a central return configuration in case the door is closed). Whats the purpose, for all the labor and material required, why not just run as a full return to the unit ?