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Bridging floor joists: proper method around ducting?

Bridging floor joists: proper method around ducting?

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  #1  
Old 12-24-12, 07:45 AM
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Bridging floor joists: proper method around ducting?

My house has 2 x 12, 12-inch o/c floor joists. The heating system is forced air natural gas.

I want to bridge around the 7" galvanized ducts. I thought about laminating two 3/4 pieces of plywood and installing that as the bridging and running the duct through a hole cut in the center. Or possibly doing the same thing with heavy aluminum instead of the plywood.

Are these ideas okay to do and are there any better ways?

Thank you!
 
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Old 12-24-12, 09:54 AM
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You're looking to cut through the 2x12's? Or are you just boxing around the ducts?
 
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Old 12-24-12, 10:16 AM
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I'm with Tolyn, I'm not sure I understand what you're proposing.
 
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Old 12-24-12, 10:30 AM
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Why do you feel the need to add bridging to these areas?
 
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Old 12-24-12, 11:33 AM
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You're looking to cut through the 2x12's?
No. The ducts run parallel to the joists and within the joist spaces.

The metal strap-type bridging was removed or bent when the ducts were installed.

Why do you feel the need to add bridging to these areas?
To minimize squeaking and creaking when walking on the floor. Plus, I may want to install ceramic tile on the floor above and I want to do whatever I can to lessen the chances of cracked grout or tile.
 
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Old 12-25-12, 09:31 AM
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I could be wrong (not a carpenter) but it is my understanding that bridging is for horizontal movement of joists. It is not necessary to replace the removed bridging.

Squeaking and creaking is from the sub-floor moving along the nails that is holding it to the joists, not the joists moving. If you are planning on tile, you will want to beef up your sub-floor with a tile backer like Hardiboard or durarock. your 12"OC joist spacing will also help for tile, not bridging.
 
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Old 12-25-12, 12:51 PM
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Bridging does add to the stiffness of the floor by tying multiple floor joist together. It spreads the loads across multiple joists and adds some stiffness to the flooring. It also keeps joist from twisting or moving (horizontal movement). Adding additional layers of plywood also will tighten up the floor. Cement backer boards do not add structural stiffness to the floor.

Squeaks are nails that are rubbing with the floor movement. They are either mis-fires that are riding on the egde of the joists. These can be bent out of the way to quiet the sqeak. Nails that are not ring shank or spiral shaft may be moving within the hole they are set in. When you go to install tile, these nails should be pulled. I screw down all my floors before tiling to prevent nails working themselves loose.

If you can get some solid bridging in the cavity, anything is better than nothing.
 
 

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