DIY subfloor repair advice...

[Bronn]

Hi all...

So I have a spot in my kitchen that has always kind of "given" a little bit when you step on it. Over the past year or so it seems to have gotten worse (it could be our imagination, but it is noticeable).

Originally, I wrote it off as poor underlayment beneath the linoleum or a bad piece of subfloor base that they put in.

I've gone under the house and there is a joint in the OSB at this location, but no signs of water, bugs, or rot. I also don't see any breakage or anything that would cause the sagging. No joist problems, etc. There isn't a water source nearby either, and it isn't in a spot where a roof leak should be the cause.

I guess my DIY solution for the time being is to just cut out some OSB inserts and put it up under the sagging joint with some nailer strips into the sides of the joists on either side and see if that jacks it up enough and stops the give.

Sound like a good plan?

[Floppin]

9 minutes ago, Bronn said:

Hi all...

So I have a spot in my kitchen that has always kind of "given" a little bit when you step on it. Over the past year or so it seems to have gotten worse (it could be our imagination, but it is noticeable).

Originally, I wrote it off as poor underlayment beneath the linoleum or a bad piece of subfloor base that they put in.

I've gone under the house and there is a joint in the OSB at this location, but no signs of water, bugs, or rot. I also don't see any breakage or anything that would cause the sagging. No joist problems, etc. There isn't a water source nearby either, and it isn't in a spot where a roof leak should be the cause.

I guess my DIY solution for the time being is to just cut out some OSB inserts and put it up under the sagging joint with some nailer strips into the sides of the joists on either side and see if that jacks it up enough and stops the give.

Sound like a good plan?

Subfloor breaks should always be over joists. Add a joist under the joint. Unless it's just the t&g joint that runs over the joists horizontally. If it is just add a piece of blocking between joists at the sag.

[Jase]

Just wad up some duct tape and stuff it in there, IMO

 

But seriously, I ended up replacing all of the underlayment in my upstairs and there is no substitute for tearing it all out and re-doing it correctly.

[Jimmy]

If the joist is sagging then do what @Floppin suggested. Just brace it and also just cut the amount you need as well and replace that portion of OSB. 

[Bronn]

2 minutes ago, Jase said:

Just wad up some duct tape and stuff it in there, IMO

 

But seriously, I ended up replacing all of the underlayment in my upstairs and there is no substitute for tearing it all out and re-doing it correctly.

I just hate to get too labor involved because I think our current plan is to sell in the next 5 years. 

The house is only 12 years old and this has existed since then in some form since we bought it new. 

I think I might add a block under the joint like Floppin' said and see if it makes it at least less noticeable.

thanks for the responses guys!

[cookinbrak]

If you can get to it easily, put a hydraulic floor jack under it, raise it up to flush, and scab a couple of 2x10s onto the floor joist.

[PandaPancake]

8 hours ago, cookinbrak said:

If you can get to it easily, put a hydraulic floor jack under it, raise it up to flush

FTFY

[Anybodyhome]

1. Determine whether it's the actual subfloor (OSB or plywood?) that's sagging and not the floor joist.

2. If it is, in fact, the subfloor and the sag is at a joint, is that joint running parallel or opposite the joists?

3. If the joint is running parallel to the joists, you'll need to install blocking:

4. If the joint is running perpendicular to the joists, the joists are likely uneven. There should only be 16" between the joists and a piece of 5/8 or 3/4 OSB or plywood isn't going to sag in a 16" span.

5. If the subfloor in that particular spot is not resting firmly on the joist or the joist appears to be sagging, you can insert shims between the subfloor and the joist. But first ensure the joist detaching from the beams, which could be causing the whole mess to begin with .

[Bronn]

22 minutes ago, Anybodyhome said:

1. Determine whether it's the actual subfloor (OSB or plywood?) that's sagging and not the floor joist.

2. If it is, in fact, the subfloor and the sag is at a joint, is that joint running parallel or opposite the joists?

3. If the joint is running parallel to the joists, you'll need to install blocking:

4. If the joint is running perpendicular to the joists, the joists are likely uneven. There should only be 16" between the joists and a piece of 5/8 or 3/4 OSB or plywood isn't going to sag in a 16" span.

5. If the subfloor in that particular spot is not resting firmly on the joist or the joist appears to be sagging, you can insert shims between the subfloor and the joist. But first ensure the joist detaching from the beams, which could be causing the whole mess to begin with .

Thanks for this... But now I am getting more concerned...

The joists look fine... they aren't sagging or lower in that spot. The OSB joint above them runs perpendicular between them.

It is the OSB that is giving. I had my wife go the the spot while I was under the house and step/jump/stomp. The joint between the OSB just gives and sags.

I feel like something at some point, possibly even during construction or prior to, just happened to get into one of these pieces of OSB (bugs, moisture?) and caused it to rot/weaken.

Underneath the house, I see no visible rot or moisture, or even a source for moisture to come from. I don't see any breaks in the OSB other than the joint between the boards.

Could the tongue have broken off of this section during original install, causing it to not sit in the groove of the opposite side? Or, could they have messed up and used a piece of sheathing instead of tongue and groove for this spot of sub?

I'm thinking I'll be able to just reinforce it with supports between the joists. As long as I see no evidence of termites or other borers, and there isn't any moisture or any signs of rot, don't you think that should be the first go at a fix?
 

[Anybodyhome]

11 minutes ago, Bronn said:

Thanks for this... But now I am getting more concerned...

The joists look fine... they aren't sagging or lower in that spot. The OSB joint above them runs perpendicular between them.

It is the OSB that is giving. I had my wife go the the spot while I was under the house and step/jump/stomp. The joint between the OSB just gives and sags.

I feel like something at some point, possibly even during construction or prior to, just happened to get into one of these pieces of OSB (bugs, moisture?) and caused it to rot/weaken.

Underneath the house, I see no visible rot or moisture, or even a source for moisture to come from. I don't see any breaks in the OSB other than the joint between the boards.

Could the tongue have broken off of this section during original install, causing it to not sit in the groove of the opposite side? Or, could they have messed up and used a piece of sheathing instead of tongue and groove for this spot of sub?

I'm thinking I'll be able to just reinforce it with supports between the joists. As long as I see no evidence of termites or other borers, and there isn't any moisture or any signs of rot, don't you think that should be the first go at a fix?
 

Either the T&G failed or they used straight edge sheathing. OSB is very good at showing signs of rot, decay and moisture and it would be very obvious to the most novice of DIYers, so I don't think you have an issue there. 

Here's how I would approach it:

Sister a pair of 2x (whatever the joist size is). This is a ceiling pic, but same principal:

Install the 2x's between the joists such that both edges of the OSB subfloor are fully supported. Also, I'd use a joist hanger versus just toe nailing the blocking between the joists- much tighter and less likely to give.  

 

[Anybodyhome]

Install the hanger, insert the 2x's and before you hang the other end between the joists, have someone step on the joint a couple times to make sure you get the 2x's all the way up underneath the OSB so it doesn't continue to give. Like I said earlier, you can use a couple cedar shims to close any small gaps and tighten it up.

[SmokinwithWilly]

Had this happen to me several years ago. It ended up being one of the floor joists was sagging a little. I ended up adding a pier under that spot and inserting a couple of shims. 

Run a string line along the joists and see if you have a noticeable gap near the weak spot. That will help you see if it's the osb or the joists.

[PhillyB]

i have a rental property built in the 60s that had sagging spots in the bathroom and one of the bedrooms. i fixed both of them by taking some shims and tapping them into place under the joists. it's tricky business - you can easily push it up too far and get an obnoxious rolling effect. once you get it right, slather them with wood glue, tap back into place, and you should be good.

i've installed extra joists underneath too, as anybodyhome suggested.

another option is to fake arson and burn it down for the insurance money

[Paa Langfart]

what ever you do dont cheap out on the repair.  when it is time to sell your place if someone finds shoddy repairs it is going to cost you a lot more than making the proper repair now.