Replacing Subfloor

The flooring under the carpeting in our downstairs greatroom consists of 5/8" particle board over 1/2" OSB nailed to the joists (doubtful that the OSB is glued to the joists). The joists are 2x10 spaced 16" OC with a span of 13’-8". There is noticeable bounce to the floor and popping sounds can be heard in various locations as you walk across the floor.

Since we will be replacing the carpet, my intent was to pull up the particle board and install 3/4" TG plywood on top of the 1/2" OSB screwed into the joists. Should this solve the bounce and noise issues? Should I also glue the plywood to the OSB?

The framing and spacing are adequate.

The popping noise you’re hearing must have something to do with the particle board breaking at loose nail locations or air gaps. I’d remove the carpet and then walk across the floor to determine what is causing the noise and bounce.

Other than that, there shouldn’t be deflection in the joists themselves with the sizing you described. It’s got to be air gaps under the particle board.

Instead of replacing the sub floor perhaps you can screw the existing floor down and then install the carpet, this has been done for years, cheaper and quicker too.

Even though screwing the particle board into the joists MIGHT eliminate all of the problems, I feel like replacing it with 3/4" TG plywood should definitely stiffen the floor more since (1) I am adding an extra 1/8" of flooring (particle board is only 5/8") and (2) the plywood is structurally stronger than particle board, correct? If I am screwing the plywood through the OSB into the floor joists, is there any reason to glue the plywood to the OSB or to not glue the plywood to the OSB?

The glue will help eliminate future squeaks.

I agree with Peter & David, 2 x 10’s 16" o.c. are more than adequate for that span, you shouldn’t have any (or minimal at worst) deflection.
2 things - 1.) I’m curious as to how old the house is. The reason being you described 5/8" particle board over 1/2" osb. I’m wondering why a builder would add thicker underlayment to a thinner sub-floor. If it is newer, one of the flooring materials could in fact be a product called Advantec which is just as strong if not stronger than plywood and be more durable. Item #2 - if you are determined to add the 3/4" T&G, I would suggest going around the entire area measuring doorways, thresholds, heating, baseboard and most importantly where this floor would meet another floor. Although you may only be adding 1/8" inch more in height, that along with new carpet and pad could cause you a whole bunch of headaches.

Like Peter and David said - pull back the old carpet, locate the squeaks, drive several long screws and they should go away.


The house was built in 1994. The builder used 5/8" plywood over 1/2" OSB in the “wet” areas (kitchen and bathrooms). The rest of the house looked like particleboard when it was installed. How can I differentiate between particle board and Advantec? I haven’t yet pulled back the carpeting. The additional 1/8" height won’t create any significant problem.

Pulled back carpeting in a corner and looked at register vent - underlayment is definitely particle board. Went under the crawl space and measured distance between each joist. Average was about 16.25 inches with a couple having 16.5 inches between them. There were also two double joists near both ends of the masonry fireplace and the spacing on either side of these was significantly less than 16". The physical measurements on the joists are 1.5" x 9", slightly less than the 1.5" x 9.25" I would expect on a 2" x 10" joist.

Only about 1-7/8" of the joist is supported on the exterior wall end versus 4.5" on the interior wall end. There is room to wedge a 2 x 4 between the foundation and the joist on the exterior wall. Would the additional end support of the joist make much difference in firming up any deflection?

I spoke with an Advantech representative who recommended against screwing through the top layer (whether it is Advantech or plywood) directly into the joist. He indicates this could create torque problems in the floor with the two layers expanding and contracting at different rates. Any comments on this warning? I actually did this when I tiled the kitchen a year ago and then added a 3/8" layer of plywood on top screwed only into the underlayment and OSB, not the joists, pryor to installing the tile. So far I’ve had no problems in the kitchen

Jim, not sure where you live but Advantech has only been in this area for a few years. I know the screw method works as someone makes a special kit to do this while the carpet is still down. Once you determine where the floor joists are you use special screws that allow you to go through the carpet into the sub floor and joists, once this is completed you take the tool they supply and snap the head of the screw off below the carpet.

Peter, you got me hunting again, ha. ha.

Squeaky Floors under Carpet

Can you tell me how to repair squeaky wooden floors that have carpet over the floor ? I have seen advertised on the internet "Mr.Squeeeky which consist of screws that break off after they are screwed into the floor. Do these screws really work ?
I never used this product, but I just checked out their website and I do believe it would work. It only seems a shame to have to pay that 39 dollars for some break away screws.
I would be tempted to try it myself… score some screws, do some practice drilling to see how much to score… and how well they break off. The last thing you want is the darn screw broken off just low enough you can’t get a pair of vise grips on it… and just high enough that you feel it with your bare feet. Know what I mean?? Anyway. If you are dealing with a floor where you can’t get to it from underneath… then these screws do look like they will do the job. Whether you buy the Mr. Squeeeky set up or try it yourself I would recommend doing the first one in the corner, where you don’t walk. Just to get the feel. And when you do it over the squeaks, add some extra weight… really weight it down over the joist, so it gets pulled in tight. With the threads going through both the underlayment/subflooring as well as the joist, the screw will not be able to pull them all together. So you want the weight on top to do that.

: I have a carpeted floor that squeaks – but we can’t get to the squeak from underneath. How do I stop the squeaks?
A: First you must find the squeak. Then use a stud sensor to find the nearest joist.
Take a utility knife and carefully cut a small hole in the carpet webbing above the joist just big enough for the head of a screw.
Wrap transparent tape around a 1 1/2-inch screw to prevent it from catching on carpet strands, and then drive it through floor and subfloor and into the joist. When it’s all the way in, put a little glue on the head of the screw and position carpet back over it.
If you have a number of squeaks, you might consider a kit designed especially for fixing squeaks under carpet. These come with special breakaway screws, a bit and a depth-control device.
Most squeaks are caused when the subfloor begins to separate from the floor joists. The nails squeak as they slide in and out of the joists. To fix these, it’s best if you have access to the floor joists.
To fix squeaks caused when larger gaps develop beneath the floor, fasten a piece of scrap wood against the nearest floor joist so that it fits snugly against the subfloor. The scrap will support the subfloor, preventing it from moving down to the joist.
For smaller gaps, apply construction adhesive to a wooden shim and slide the shim into the gap between the joist and the subfloor. But don’t force the shim into place; if you do, you’ll only create a wider gap between the joist and the subfloor.
If the problem stems from the floor separating from the subfloor, use a short screw to fasten the subfloor and floor together. Don’t use a long screw: it could go all the way through the floor.

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Squeeeeek No More®for Carpeted Floors](, stops floor squeaks from the top of the floor by safely going through the carpet!
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By gesuesss, Peter, you were not dreaming. Here it is.

Marcel :mrgreen:
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Marcel! That’s where I saw it!! it was an episode of ask this Old House.

I new I wasn’t crazy. Sure beats tearing up the 2 sub floors and laying a new one.

Thanks Marcel for the links.


Peter; how are your jobs going? Anything knew?

How far are you from Eping?

My sister in-law lives there in the boonies somewhere, ha. ha.
Nice place.

Marcel :slight_smile:

Marcel, Jobs are up and down this year, lost a few but we are getting by.

The job I had in No. Berwick went south due to zoning, It’s gone from a complete second story addition to a vinyl siding job, OH well…

I live about 30-40 minutes north of Epping, which I believe is the center of the universe isn’t it? If you know someone there ask them!!!

Peter, if I ever go back to Eping, I might swing by that way just to say Hi. to an Hi. ha. ha.
PM me your address and cell phone, whether it is next year or so, if I need it I will stop by and say hello.

Marcel :slight_smile: :slight_smile:

Marcel, I would be very happy to get together with you. I’ll send my contact info. to you. By the way where is Winslow ME?


Funny Pete, at least I am near a highway, and the only one at that. Interstate 95, ha. ha. across the river from Waterville, Maine.

One hour an one half North of Portland.

Marcel :slight_smile: :wink:

I did a commercial inspection up that way in LA a few months back.

Not as spectacular as the on in CA. but there was no smog!!!

Sqeaking is almost always caused by sheathing sliding up and down on nails as it flexes while being walked on. Nails will pull loose over time and provide room for sheating to flex, especially if the joists are not crowned correctly. Anywhere you have a joist crowned down with joists on either side crowned up, nails will back out in the joist which is crowned down resulting in squeaks toward the center of the span and pops toward the bearing points where less flex has not yet worn the nail holes so much.

Gluing plywood to OSB couldn’t hurt, but what’s most important is to pull all the nails.

Kenton, I agree with what you are saying, but something to me dose not sound right.

In one of Jim’s post, he mentioned that the 5/8" particle board was installed over a 1/2" OSB.
Well to me that does not sound right.
In this area, the standard would be to install a sturdi floor or Advanteck 3/4" T&G or square edge nailed and glued and later apply a 5/8" underlayment plywood.

The reason for plywood would be for the fact that most VCT and linoleum Manufacturers will not warranty their Product if installed on OSB unless another 1/4" product of their approval is installed. Carpeting makes no difference.
Not sure what the specifications might be in your area.

Jim also asked what the difference was between particle board and advanteck. Particle Board Jim consist of pressed sawdust and advanteck is like an oriented stand board that looks like wood shavings.

I have seen on one occasion where OSB Advanteck got so saturated before a building got enclosed, that it produced a bright Pink Mold. Had never seen it before. Once cleaned properly and dried up, everything was fine.

The trick Jim would be to screw your underlayment to the joist as much as possible and maybe if accessible from underneath, screw that 1/2" OSB to the 5/8" plywood. I have a feeling that the 1/2" material is sagging and creating air pockets that was mentioned.

Jim, you also mentioned that the spacing in between your joist was 16.25" to 16.5", how can that be for 16" O.C. spacing framing?

Marcel :slight_smile: :slight_smile:

Thanks for getting my post back on track.

It may not sound right, but it definitely is 5/8" particle board over 1/2" osb. I suspect it was done to save money. So, as clarification, I will not create any potential problem by screwing the underlayment & osb directly into the joists (see concern raised by the Advantech rep in my post earlier in this string)? My intent was to screw into EVERY joist with a 6" to 8" spacing between screws.

There are 25 joists for 31’ of flooring. The joist spacing at four points near the masonry fireplace is much tighter than the rest of the floor (ranging between 2-3/4" to 12-7/8"). For the remaining 21 joists, the average spacing works out to slightly more than 16-1/16" but the spacing is not uniform. This results in 10 of those joists spaced more than 16-1/16" apart, one exactly at 16-1/16", and the remaining 10 spaced less than 16-1/16". The largest spacing between joists is 16-7/16".