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  1. #1
    Join Date
    Feb 2005
    Posts
    5
    Hey,

    I'm having some HVAC work done and we're rerouting some returns. My buddy wants to use the joist bay in our unfinished basement as the "duct" for part of the return.
    The idea is to sheet metal the bottom of the joists, enclosing the bay, and with the subfloor and floor upstairs, it will be airtight.
    I've never heard of this. Have any of you?
    Is is safe? Functional? a good idea?
    Please let me know.
    Thanks


  2. #2

  3. #3
    Join Date
    Feb 2005
    Posts
    5
    Yes,

    except with sheet metal and not rfoil.
    This isn't such crazy idea then?

  4. #4
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Okay if it's truly air tight(all sides and the ends),in our area it's not allowed by code,as the wood is flamable.I know it's common in other parts of the country.


    Oh,it also needs to be large enough to handle the airflow required,may need more than one.

  5. #5
    Join Date
    Sep 2001
    Location
    East Stroudsburg, PA
    Posts
    13,215
    Very common, just bear in mind that you can only do that with the return, and sealing it to the return ductwork is necessary.

    There are other products available, such as thermopan, and the dubble-bubble that can be stapled up, but sheet metal panning is the best way to go.

  6. #6
    Join Date
    Feb 2005
    Posts
    5
    The joist bay is 14" by 9 1/2"

    "sealing it to the return ductwork is necessary."

    You mean connecting it to the return so it functions, right?

    Thanks for your help!

  7. #7
    Join Date
    Sep 2001
    Location
    East Stroudsburg, PA
    Posts
    13,215
    Yep. You want to attach the panning to the joists with roofing nails every 4-5". The panning should be sealed off from the area that it's in, and the ductwork should be connected to the panning. IOW, don't leave the panning open on one end and defeat the purpoose of the panning.....

  8. #8
    Join Date
    Feb 2005
    Posts
    5
    Ok,

    I get it.
    We're cutting a hole in the floor and running a duct UP from that hole. That duct will have vents for returning air.
    The joist bay under the hole is going to be sealed the length of the bay with sheet metal and attached to a duct on the other side of the house.
    The duct it's attached to feeds the return on the furnace directly.

    So, there's no opening's except for where the ducts are.
    Thanks again, this site rocks!

  9. #9
    Join Date
    May 2004
    Location
    Rapid City, SD
    Posts
    7,415
    Just curious why you choose metal?

    I know everyone (including me) preaches metal on this site (as opposed to flex). But sometimes the metal panning can "bong" when you walk across the floor, or as the house settles in the future.

    Just throwin my 2 cents out there.

  10. #10
    Join Date
    Feb 2005
    Posts
    5
    what are my choices?



  11. #11
    Join Date
    Jan 2002
    Location
    tip of the mitt
    Posts
    1,982
    Good stout metal 22 or 24 guage with a pitts on one end and a crossbreak. There will be no oilcanning.
    I have my own little world. But it's OK...they know me here.

  12. #12
    Join Date
    Aug 2003
    Posts
    1,841
    klipper Hey,

    I'm having some HVAC work done and we're rerouting some returns. My buddy wants to use the joist bay in our unfinished basement as the "duct" for part of the return.
    The idea is to sheet metal the bottom of the joists, enclosing the bay, and with the subfloor and floor upstairs, it will be airtight.
    I've never heard of this. Have any of you?
    Is is safe? Functional? a good idea?
    Please let me know.
    Thanks

    Yes we do it all the time in wv we use duct board or metal to pan with check out your code first.

  13. #13
    Join Date
    May 2004
    Location
    Rapid City, SD
    Posts
    7,415
    Whoops, guess I should have posted what else you could use. I typically use a lot of thermo-pan (basically a cardboard type stuff). Also, it's true that a thicker metal (22 or 24 ga) probably won't "bong", but around here all I have ever seen is really thin, like around 30 ga.

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