Pine floor flexing between joists.

Old 10-28-14, 11:53 AM
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Pine floor flexing between joists.

Have a home built in 1930s with pine flooring. While trying to eliminate squeaks I noticed that in between one particular section of joists the floor boards were all bending when stepped on in between the joists, and I attributed it to a large gap (almost 23 inches of air) between joists in that particular section. There was no subfloor installed, damn Hoover and Roosevelt. Short of installing a new joists, is there anything someone could suggest to brace the boards between the joists?

My thought was putting a 1x4 running up the center, parallel to the joists. I would brace them with 2x4s crossing between the joists. I would at least put construction adhesive on the top of the 1x4 (against the bottom of the floor) and maybe screws if I still noticed a bending. I suppose option 2 would be to use plywood, again with construction adhesive and 2x4 bracing.

Not sure if it matters but the joists are 10x4s true to size. I do not notice ANY bending in the joists themselves so it's not the normal bouncy floor issue.

Thanks for any solutions you can offer, particularly ones that don't require second mortgages.

Last edited by Towsonite; 10-28-14 at 02:48 PM.
Old 10-28-14, 02:15 PM
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I'm not sure I understand your 1x4 plan Do you have access from beneath? if so, I'd add a joist between the joists which would give your floor the support it needs.
Old 10-28-14, 03:48 PM
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I'm not understanding the 1x4 idea especially since you also mention using 2x4s. I don't know if you would call it a cripple joist but at each end of the area I would install solid blocking between the existing studs as headers. They don't have to be the same size as the current studs. Then run a short joist between the blocks to support the floor. If it's a really small area you might get by with 2x4 but I'd probably use at least 2x6 to allow more nailing area.
Old 10-28-14, 05:24 PM
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If your joists are 4x10's, true measurements, it ain't the joists bending, but the flooring between the spans. Yeah, there should have been a subfloor installed, as is the practice, today. In the '30s you probably were lucky not to have a dirt floor. If you do decide to install false joists, you will need to use 2x10's with very good support at each end. Can you tell us what the unsupported span is between where the existing joists rest?
Old 10-28-14, 10:00 PM
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Chandler, you're correct. It's just the flooring boards that are bending. The unsupported span between the joists is 23 inches. The neighboring spans are about 19 to 20 inches and the floor boards do not bend like in the problem area, so my thought was it just needs a little support.
Old 10-29-14, 02:44 AM
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I think a little support will tend to flex and more squeaks,

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