[thewordsmith]

On internal walls, how does one deal with "top and bottom" 2x4's when running ducts from say 2nd floor to the basement? the 2x4, being only 3 1/2" thick, seems too small to cut a hole through to pass a duct down. Do you just cut out an entire section of the 2x4? I'm clueless. Any links and pointers would be helpful. Thanks so much!

 

[gregzoll]

You cut a hole down the length of the drywall, then either use Duct board to create the duct in the cavity, or build out the wall to allow the 6" or 8" duct the room that it needs. Keep in mind, if you are feeding multiple rooms with this feed, you are going to need more than one 16" by 4" space for the volume needed to feed all of them.

Then there is the issue of distribution to those rooms, so that means cutting into the ceiling drywall to do that.

 

[Marty S.]

Lose a little living space and make a chase for the duct. Much better than chopping up the structure and it will work better too.

 

[beenthere]

Cut out all but an 1/8" on the 3-5/8" sides. Put a brace plate on it afterward.

 

[joecaption]

I try to run the chases in a closit whenever possible.
Or add one to a room so I can run it.

 

[REP]

Well I suppose that if you've never done it you just dobn't know but a standard size stack ducting comes in 3 1/2 inch and 2 1/2 inch sizes.It comes in 10",,12",,and 14" withs.On internal walls you always use the 3 1/2" stack and external walls you use 2 1/2 " stack so you can get at least 1" of insulation in.
And to answer your question yes you cut the top and bottom 2x4 out so that the stack can get to the rest of the system.

 

[beenthere]

Well I suppose that if you've never done it you just dobn't know but a standard size stack ducting comes in 3 1/2 inch and 2 1/2 inch sizes.It comes in 10",,12",,and 14" withs.On internal walls you always use the 3 1/2" stack and external walls you use 2 1/2 " stack so you can get at least 1" of insulation in.
And to answer your question yes you cut the top and bottom 2x4 out so that the stack can get to the rest of the system.

The inspectors here frown on us if we cut out the entire 2x4. And have to install a brace plate weather you cut out the entire 2X4 or not.