Floor joist twisting

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  #1  
Old 02-19-12, 08:46 AM
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Floor joist twisting

Hello, I have what I believe is called floor joist twisting. The floor joists appear to be coming apart at their connecting point under the i beam.

My questions are:
1. How serious is this problem?

The reason i want to fix this is because I wanted to do solid bracing between the floor joists to remove some bounce in the floor. I want to make the floor joists 16" on center again. Right now they are a little off of 16" centers.

2. Any ideas how I can pull the joists together and secure them together again?

There isn't much over lap under the ibeam so I'm concerned if I drill it and pull it together with a large bolt it might split and reduce the strength of the board even more.

Earlier I was trying to use a hammer to pound the nails back together and the joist was sliding along the i beam.

 
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Old 02-19-12, 09:34 AM
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If nothing is holding the joists out of position, like drywall or flooring above, then it isn't that difficult to pull them together. Unfortunately, in the real world a 14.5" block and a 1.5" joist never adds up to 16", so a saw cut or half a cut less than 14.5 seems to work better. Just measure as you go to be sure you don't accumulate.

Nails will rarely pull boards like that together. IMO, I would use 4" torque screws, at least one on each side to pull them to where you want, and then a couple of 3" up higher to secure them. The shift in length may be needed to get the screw and drill into the 14.5" space. That depends upon your tools.

The other approach would be to pull the boards into place by other means and then secure with screws. But a torque screw with a washer if needed can pull like crazy.

Bud
 
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Old 02-19-12, 10:24 AM
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I don't quite know all the details of what is going on in your home, but that picture you showed doesn't concern me at all. It appears the joist has cupped or was cupped when it was installed. I would not try to pull that back together. The strength is derived from the joist sitting on top of the beam. The connection made to the other joist is really just to hold it in place until the rest of the house goes together. Not having blocking between the joists is more of a concern to me. How old is the home? Do other joists should this type of movement? If so, could you say that joists appear to be rolling over?

Why are you so set on getting the joists exactly 16" OC? Are they that far off? You aren't going to have much luck doing that with flooring nailed to the top of them.

Check out this link on bouncy floors: 6 Ways to Stiffen a Bouncy Floor - Fine Homebuilding Article

And this one on bridging: The Importance Of Floor Joist Bridging - Part 1
 
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Old 02-20-12, 08:07 AM
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More Details

The house was built in 1965. I am concerned about twisting or cupping just because all of the joists appear to be doing this. The reason I was thinking about pulling them back together so I could brace between the joists, under the i beam. Is that a good or bad idea?

I was thinking I would glue two 2x10's together then screw it in place under the beam to keep the joists from moving at all.

My intentions are to add solid bracing, to brace the subfloor and the joists, because the subfloor feels a little weak between the joists.

I was considering 16" on centers just because there is some play in the joists, some are 14" inside of joist to inside some are 14.5",inside of joist to inside of joist, etc. Not dead set on it but thought it would be good to move them back to original spacing if possible.

Is it good to solid bridge if you do sistering with say plywood or another 2 x 10? Again one of my concerns is the subfloor seems a little weak so I thought the solid bridging would help that a little bit too.

Down the road I was considering using the squeek no more screws to top fix the floor into the sisters or bracing.

Thanks for the help.
 
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Old 02-20-12, 10:51 AM
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Why do you keep saying "under the I beam"? Aren't the joists above the I beam?

You are assuming the joists were set perfectly 16" OC to start with. You shouldn't make that assumption.

There is a difference between a bouncy floor because the floor joists are flexing and bounce between the floor joists because the subfloor is flexing. So what problem are you having? Is it dipping down between the joists or is the whole floor bouncing when you walk across it?
 
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Old 02-25-12, 06:54 PM
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If it were mine, I'd live with it. Not worth the effort, and to accomplish exactly what? If you were to compare all of the room sizes and out-to-out dimensions of your house with the dimensions shown on the as-built plans, I suspect you would find more than just a few discrepancies.

And the subfloor fasteners at the tops of the joist ends will likely restrain them from moving, or worse yet possibly get split and/or damaged.
 
 

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