Construction methods?


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Old 05-01-07, 04:03 PM
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Question Construction methods?

Can someone please give me or point me to a decent description of what
construction methods are allowed for air returns in a residential
application?

Specifically, are we still allowed to box in the space between a
couple of floor joists as part of a return air run? If not, what else
*is* allowed?

This is in 60 year old wood frame construction, with gas forced air that replaced the original "gravity" furnace.

Thanks!

Mike D.
 
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Old 05-01-07, 05:20 PM
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What's Allowed

In general, using panned off floor joists as a return duct system is not acceptable, BUT, you should ask your local officials code related questions since codes, or the lack thereof, vary widely from area to area.
 
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Old 05-01-07, 06:14 PM
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Grady wrote:
"In general, using panned off floor joists as a return duct system is not acceptable, BUT, you should ask your local officials code related questions since codes, or the lack thereof, vary widely from area to area."

Thanks Grady. I will be pulling permits and working with the local inspectors, but at this stage I'm trying to learn enough to not feel completely ignorant talking to them.

So, ducting built to the same standards as supply runs is what is required? Or are there any permissible differences?

Thanks,

Mike D.
 
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Old 05-01-07, 06:57 PM
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Sheet rock, wood, etc is allowed by code here.
 
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Old 05-02-07, 05:31 PM
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Codes

Airman's reply just goes to show you an example of how codes differ from place to place. My local codes used to allow systems like Airman's. Then the floor joists had to be panned off with either sheet metal or ductboard. Now we have to use a duct system like that used for the supplies.
 
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Old 05-02-07, 07:19 PM
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Our is the same as Airman. They don't allow this "Cardboard Panning". must be metal on exposed area, otherwise, sheetrock.
 
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Old 05-02-07, 07:24 PM
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Panning

Jay, are you allowed to use ductboard or other non-combustables or just metal & rock?
 
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Old 05-02-07, 07:57 PM
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I've never seen ductboard used around here.

Flex can be used, but mostly found in attic or drop ceiling.
 
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Old 05-03-07, 11:45 AM
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Thank you gentlemen! At least I understand the degree of variation from place to place well enough to know that asking the inspecter what's allowed around here won't make me look foolish.

Being able to pan the joists and block the ends would simplify construction, but worst case I'll have to do a bit of carpentry to make room for proper ducts.

I've stepped through the design process for adding these two rooms to the system and had worked out nearly every detail of the job except for this. Thanks for helping me finish my planning.

Be well,

Mike D.
 
 

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