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5/8 T&G OSB on 1by's for Sub-floor


dbdezyne's Avatar
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10-01-16, 11:26 AM   #1  
5/8 T&G OSB on 1by's for Sub-floor

I'm in the process of doing some bathroom remodeling. The original floor has various size 1by's laying at a 45deg angle across the floor joists. On top of that is 3/4" particle board. I'm taking up the particle board and laying 5/8 T&G OSB. My question is what would be the best way to attach the T&G? I probably prefer screws, but should the screws go all the way through the 1by's into the joists or just into the 1by's. Should any glue be used?

thanks

 
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10-01-16, 11:40 AM   #2  
Use 2" decking screws and NO adhesive, missing the joists intentionally with the second layer screws.

 
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10-02-16, 04:32 AM   #3  
Thanks Chandler, I thought that may be the case, but what is the reasoning behind not anchoring to the joists? Is it because the 1bys already perform the connection to the joists?

 
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10-02-16, 05:43 AM   #4  
Yes, the 1x lumber and the OSB must "slip". Yeah, it doesn't sound like they will, but with both connected to the joists, they become one, and they expand and contract at different rates, so decoupling the top layer from the joists, you allow this movement to take place.

 
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10-02-16, 05:49 PM   #5  
What type of screw pattern would be appropriate if the joist are avoided?

 
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10-02-16, 07:13 PM   #6  
The real reason the joist are avoided is because the subflooring always has slight low areas between the joist and you want to draw the next layer down so there's no gaps that are going to cause the floor to flex.
No way would I suggest using screws to attach the added layer for several reasons.
As the screw goes in it's going to lift the OSB, it's going to crush the wood fibers and leave raised spots, cost and take at least 5 times as much time as what it would take to do the same job with 8D ring shanked nails in a nail gun.
Only place I would suggest using deck screws is in the old 1X flooring under what your planning on installing.
That second layer needs to be attached every 4" on the edges and from 6 to 8" in the field.

 
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