Hi everybody,
This is an awesome board for somebody like me, but I have not found my answer so I hope this post will get me some.
I am installing bamboo flooring (second floor room) and realized that 1) subfloor is very squeaky, 2) it is not level and 3) it moves too much.
To investigate the squeakiness I cut a hole in my subfloor to work a bit on the joists to make them less squeaky when I understood my problem with points 2 and 3. My joists are 20+ inches OC apart (max is 24 inches - in the middle of the room) and the subfloor itself is 3/4 inch plywood, but over time (it is a newer house - approx 10 years - but still) the plywood has warped and as such it sits lower between the joists compared to on the joists. The normal high difference (between the "on the joist" and "in between the joists") is close to 1/4 inch, but the problem is when I step on the plywood between the joists it moves another good 1/8th of an inch (if not even more).
So what is my best solution?
Rip the subfloor up all together and replace it with 1 inch plywood to give it extra rigidity? Cover my current subfloor with extra layer or 1/2 inch plywood to give it rigidity? Cover the current dips with something like sand, sawdust, etc.(cannot really sand the plywood from the joists location or it will seriously weaken the floor - i think) and hope the plywood would not warp further (because the additional movement of 1/8th of an inch is within tolerable limits of floor installation)??
Sadly I discovered that there is nothing I can do about the squeaking (it is very wide spread and fixing it is close to impossible), so I hope I can at least fix the issue with the floor "moving".
Thank you,
Indrek

did u determine where it is squeaking from? is it the joist or the subfloor..

1st..

screw entire sub floor...does it still squeak after this?

if its the joists...its not because they are 24 O.C...but the span would be more important

is it the joist hangers?

are there metal braces between them? this can cause squeaks..change them to wood or make sure that they dont touch where they cross..

you can absolutely fix the squeaks..you just need to figure out why they do..

if this corrects the problem..you can then add an additional layer

Thank you for the replies so far, but I need to clarify some things here and although I drew a great pictures of it, I am having hard time showing it here as I do not know how the attachments work.
Hope this is it:


So to explain (completely lacking any technical lingo here). The "A" is the main beam. "B" and "C" are the joists - "B" is the floor joist for the 2nd floor and "C" is the ceiling joist for my 1st floor. Now "D" is a complete mystery to me. I thought it was placed there by inexperience, but I have seen some pictures on the web that have that same piece. "E" is just what it is and the gray area is the... no clue what it is called but it is metal with spikes. (man I suck at this). For the gray metal stuff please see this link - http://www.bethesdabungalows.com/denton ... %20web.JPG - this is what I am referring to). So the squeaking is coming from 3 possible places - between A and D (any where between that), D and E or E and C. All I know is that it is from that area. I put almost a whole bottle of talcum on it and nothing happened. I hammered the bottom part good and the squeaking went away for... 30 seconds, but then it is back.

The reason why I call it a lost cause is that there are about 20 places like that under that one room (3 beams and 5 joists - middle beam has joists on both side), so IF I decided to rip up the whole subfloor then I might be able to fix it in all places, but currently I have opened only this one place only.

BUT... That is not my main concern anymore (one day I might be able to learn to live with this squeaks and knowing that it is just bad construction - my whole house squeaks like that). I would love to get rid of the squeaking, but my main problem is my subfloor warping. Now it looks like this -

and I think that is a direct result of joist spacing and the thickness of the plywood. As said before the spacing is over 20 inches OC apart and the plywood on top is 3/4th thick. I think the 3/4th is OK if the spacing is 16 inches OC but more than that and the wear and tear of the plywood will results in warping. So back to my original question - should I just replace the subfloor with a 1 inch plywood or is there anything else I should be thinking in regards to getting the subfloor to level and increase the subfloor rigidity?
Thank you all,
Indrek

its sounds to me that if you [ull up the existing plywood..this will give you a bettr look at things..
you will be able to walk out the joists and determine the point that actually squeak..

my money is in the fastening and at those metal bridges...

wherever there is metal and wood...also check the joist hangers if they were used..which most likely they were.


I am not a framer or structural engineer, so i cant give any advice as what to actually do to correct...