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Discussion Starter · #1 ·
I am putting in a partition wall that runs parallel to floor joists below and rafters above. The floor joists and rafters are offset by about 7” and I’m going to build the wall under the rafters. This will put the wall between the floor joists below. I read elsewhere that the floor sheathing should be enough to support a non-load bearing wall like this without blocking the floor joists. I’m new to framing, so should I be concerned?
 

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retired framer
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In new builds we never worried about it for years but just lately they have been calling for a joist under the wall here.
How thick is the plywood? I am not sure anyone worries about it when you are just adding a wall.
 

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Discussion Starter · #3 ·
In new builds we never worried about it for years but just lately they have been calling for a joist under the wall here.
How thick is the plywood? I am not sure anyone worries about it when you are just adding a wall.
I believe it is 3/4” but I’m not at the property currently. I knows it 3-ply.
 

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I (always) agree with Nealtw... but, I'm thinking that if you have access to the joist below the floor it'd take a pair of seconds to install some Simpson hangers and bridge the gap. Or even bridge with a double joist at each end of the wall and then add a proper joist between directly under the wall.

646992
 

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Discussion Starter · #5 ·
Thank you! If I did the blocking in the first image, could I use solid blocks between the I-joists (that’s what the floor joists are)? I think that approach would be easier as the span is so large at about 20 feet.
 

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Just jumping in here, but owning a 40+ year old house and doing some work on it I have see several places where support would have been a definite plus. Even non-load bearing walls will move over time, trust me.

If you have the opportunity, definitely add some support, especially if this is a long term home.
Bud
 
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Discussion Starter · #11 ·
If the existing framing is engineered I-joists, you will need special hangers to connect blocking.
I was reading about connecting an I-joist block to the top and bottom plates of the spanning I-joists. So, I was hoping to either toe nail solid blocks (non-I joists) or to add a nail plate to the blocks - probably will small pieces of plywood that are wider than the blocks and nail that into the spanning joists’ top and bottom plates.
 

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retired framer
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They are TJI 360 14” depth I-joists
My guess would be to add 14" wide plywood and then the block, but I would call a TGI supplier, they can make a call and find what is the correct method.
 

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Discussion Starter · #14 ·
My guess would be to add 14" wide plywood and then the block, but I would call a TGI supplier, they can make a call and find what is the correct method.
That aligns pretty closely to what I read on another site. That makes sense.
 
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