Flooring Forum - DIY & Professional

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John L

Jan 19, 2023
Looking for advice on leveling (or more accurately, flattening) a floor before installing subfloor. I'm down to the joists and have one joist that's lower by approx 1/8" than the two adjacent joists. Sistering is not feasible due to plumbing/HVAC. Can I rip down some 2x4 shims to glue and staple to the top of the joist? ..or is this a future problem? Should I even worry about an 1/8" over 16" o.c. when adding an additional 3/8" underlayment on top of the 3/4" subfloor?
The 2nd area that I hoping to level (slightly) has a more substantial slope: 1" over 7 feet. I can sister 2 of the joist relatively easy, but can only shim the other 3. The joists are not accessible from below (finished space). And, yes, the joists are structurally sound... Same question as above: Can I shim with ripped 2x's glued and stapled?

Thanks for your help!
John - the newbie.
You gotta ask your self if adding shims is going to cause a peak and make the area out of flatness standard for what your doing. Lots of times I'll sand one side down or use a hand planer.

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