Subfloor advice needed

[Trekbike]

So here's the deal.   I'm in process of installing 3/4" hardwood on the second story of my house.   Everything has been going well until I get to the final room which is the master.    We've had a few places around the house where the subfloor creaked when the carpet was down.    Up until the master, the creaking has been solved after I went through and screwed down the subfloor in all the rooms with some 2" long subfloor screws.  

 

So here's the trouble in the master.   Even after screwing down the floor I still have an area that creaks.   I went back and added more screws to the area.   Still creaks.    I went and got 3" long screws and swapped them out instead of the 2" long screws.   While the creaking has maybe gotten slightly better, it's still making noise.  

 

Honestly at this point I'm wondering if the noise is coming from the joists themselves and not the movement of the subfloor on top of the joists.   One area of note, in the area of the creak, the framers messed up and had one joist laid off the normal 16" centers.   It's the only one in the room like this.   So the spacing in this area is 16",19",13", and then back to 16's.   So I'm guessing this isn't helping but not sure if it's the root of the problem.   Also there is a subfloor seam to the left of the "off spaced joist" but it doesn't necessarily creak right there.   In listening at floor level while someone walks across the floor, it doesn't seem to be making noise in one specific spot so this has been half the battle in figuring out what is going on.      

 

Short of pulling up/cutting up the subfloor to better see what's going on, is there anything else to try?    If it's flex in the joist system the 3/4" hardwood might help some I'm guessing.   But once, I lay the hardwood down, it's down regardless of creaks or not.    The house is about 25 years old and I've owned it the whole time.  

 

I'm hoping someone can offer some advice.   

 

 

 

 

[Ted S.]

#### that sucks after doing all that work. If it's a joist and you can find out for sure, it might help to brace the joists with adjacent planks, I.e., screwing a few planks crossways into the problem joist and a few others to redistribute stability.

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EDIT: If you can talk to a pro carpenter, do that before investing in my suggestion. Edited March 6, 2016 by Ted S.

[quietguy]

Are the joist regular 2x material?  

 

If so, you can drill a few larger holes between your screws and squirt in some construction adhesive.  If it is I-beam construction, that presents some other challenges.  

[Trekbike]

Are the joist regular 2x material?  

 

If so, you can drill a few larger holes between your screws and squirt in some construction adhesive.  If it is I-beam construction, that presents some other challenges.  

 

Yes, regular 2x joist.   

 

On the adhesive suggestion, since the creak seems to be moving I'm not sure where to try the adhesive.   Right now the screws are about 4" apart, not including the original nails, so I'm not seeing how the stinking thing can still be making noise unless it's coming from the actual joist.    :wall:

[MacGyver]

If you've got a seam that isn't centered on a joist, you're going to squeak sooner or later - regardless of the length of the screws.

[quietguy]

Yes, regular 2x joist.   

 

On the adhesive suggestion, since the creak seems to be moving I'm not sure where to try the adhesive.   Right now the screws are about 4" apart, not including the original nails, so I'm not seeing how the stinking thing can still be making noise unless it's coming from the actual joist.    :wall:

Is the noise coming from right beneath you, or from the edge of the room?  If its under foot, then the adhesive should help.  If it is more distant, then you would probably have to pull the subfloor to figure it out.  

[quietguy]

If you've got a seam that isn't centered on a joist, you're going to squeak sooner or later - regardless of the length of the screws.

That was exactly my thought.  A good adhesive will create a bumper to keep the panels from wearing against each other in the problem area.  The sound moving around is probably just areas along that seam that are rubbing together.  

[Trekbike]

If you've got a seam that isn't centered on a joist, you're going to squeak sooner or later - regardless of the length of the screws.

 

My comment earlier about the seam wasn't clear.   The seam I was referring to is centered on top of a joist as it should be.   It is on the joist to the left of the 19" span.    So I was wondering if the extra 3" span in that one section was enough to make the seam move.   That seam though has the crap screwed out of it now so I can't see how it can still be moving.    

 

Is the noise coming from right beneath you, or from the edge of the room?  If its under foot, then the adhesive should help.  If it is more distant, then you would probably have to pull the subfloor to figure it out.  

 

Yea, that's the problem.  It seems to be coming from somewhere else and moving around.  I'm going to give it another try to track it.   

[No_0ne]

If the noise is emanating from a seam or along a wall (where there may not necessarily be a joist) sometimes pouring something like Dawn dishwashing detergent will stop the squeak by providing some lubrication between the joint ...

[peejman]

Is the ceiling under it accessible? You might try listening there and looking or feeling for movement while someone walks.

Is there plumbing or significant wiring in that floor? Could be more movement than usual due to holes drilled in the joists for pipe or wire passage.

[Trekbike]

Well after spending way too much time tracking the noise I decided to cut into the floor. I'm taking up a 4x4 section. I'm off to get some plywood before the store closes. I'll update the thread with the outcome of my endeavors.

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[Trekbike]

After cutting up that section of the floor I think I might have found the trouble. The framers installed two of the cross joist braces on a vertical angle. The result was contact with just one thin edge which would contact the subfloor when you would walk across it.

It will be the end of the week before I can fix and put things back together due my work schedule. So hopefully that will solve the problem.

Thanks to everyone for their replies.

Sent from my SCH-I545 using Tapatalk Edited March 7, 2016 by Trekbike

[pcrc11]

The only way to eliminate squeaks in a floor is to glue the plywood to the joists with a construction adhesive like liquid nails. That is the way it SUSPOSED to have been done when it was installed. Glue all joists and the tongue and groove seam as well. If it is already done you are just going to have to live with it.

[bigun]

Old trick for hard wood floors was to spread baby powder on the whole floor. Sweep it back and forth with the boards to get it between the boards.

[Dolomite_supafly]

Run some screws down in between the seams and see what happens. Just a couple over the course of the seam and see if it gets better. I fixed a few noisy spots that way.

[RED333]

Let it make noise, lets ya know the wife is coming up from behind.

[tacops]

You could try turning the volume knob clockwise.  This works for a knock in the #7 cylinder...but not for long. :doh:

 

Seriously, it sounds like the above answers pretty well covered the options.

Edited March 8, 2016 by tacops