Replacing Subfloor

Jim, so what did the Advanteck Rep. have to say and what were his recommendation to you on what to do? Just curious.

Marcel :slight_smile: :smiley:

Your reasoning makes sense, Marcel.
I think the 1/2" OSB was someone’s mistake. That won’t work for a floor, way too much deflection. After the OSB was all installed someone who knew what they were doing showed up, said “well, we can’t pull it up without dinging it up so bad we can’t return it, so we might as well leave it down. No point in sheathing with 3/4” if there’s already 1/2" down there", so they went with 5/8".
Since they didn’t know what they were doing, they didn’t glue the OSB to the joists, and now there are squeaks. Scewing to joists should help

Sounds like a likely deduction of events to me Kenton, and I agree, if it is screwed down properly, it should help or alleviate the problem but might not appease the Advanteck Rep. because the top layer is plywood. ha. ha.

Marcel :slight_smile: :slight_smile:

Because it is only 1/2" OSB and because particle board does not have the strength of plywood, my intent was to replace the particle board with plywood and screw through both layers. Surely this would create a stiffer floor than just screwing through the particle board, no? It can’t be just gaps between the particle board and osb that is the movement I feel as the lamps on my end table will vibrate when I bounce in the middle of the room (end table and I are on different sheet of particle board) - it has to be joist movement.

However, the Advantech rep recommended against screwing through both layers into the joist regardless of whether I use plywood or Advantech. He indicated I could be creating torque problems with the different layers expanding and contracting at different rates which would then induce squeaks. He recommended screwing the OSB into the joists (after removing the particle board) and then screwing the plywood or Andvantech into the OSB but not the joists. Seems to me if I follow this route, the floor will be less stiff then if screwing both layers directly into the joists. I don’t know if his “torque” concern is valid.

You could add a second layer of 1/2" OSB, Glue the layers together with PL400 and screw both to the joists. Stagger the joints on the second layer and you’ll have a solid OSB floor an inch thick w/no differential expansion/contraction problem.

While you’re down to one layer you might pull up a few sheets of OSB and jamb some 2x4 scrap, broken cinder block and misc. stones under half the joists. I’ve seen so many of those lately it’s beginning to feel like standard practice.

Seriously though, you could take advantage of easy access to install a strongback/girder at midspan.

Good advice Kenton.

Personally, I think screwing the sh#t out of the existing material and then adding an underlayment to the requirements of whatever flooring material is used would meet the Advanteck Rep’s recommendation and strengthen the floor properly without squeaks.

The alternative, if I understand Kenton’s post, would be to sister the floor joist at every other one if that is feasible.

The screw method would work for me and Bridging would be an another alternative from underneath.
Solid bridging could be added to the mid span of the existing floor joist which would provide additional support for the OSB and also modify the existing floor system to more of a diaphragm component.

Good luck.

Marcel :slight_smile: :slight_smile:

Before you start, you should check the floor joist from under the crawl space for bridging (criss cross metal or wooden supports between each joist) or solid blocking down mid-span of the floor joists. If it’s not there, I would add some solid blocking to help stiffen up the floor system. After ripping up the carpet and underlayment, locate the squeaks (check the underneath side if maybe you can add some shims) and screw the sh*t out of the subfloor. Add the new plywood underlayment, carpet and you should be home free.

If you’re doing this yourself good luck, ripping up the partical board may be a daunting task at best.:wink:

I was suggesting installing a girder, Marcel… like a double 2x10… perpendicular to the joists and beneath them, at about the center of the joist span.

Now, Kenton, how would you right that up if you were to inspect that one?

The floor structure seems to have had some sagging difficulties in the past which is showing some reinforced cross beam support added to eliminate sag and bounce to a previous condition. Would recommend a Prominent General Contractor to assess the condition prior to closing. ha. ha. :wink:

Marcel :slight_smile: :mrgreen:


Instead of trying something that will “maybe” solve your problem, why don’t you just “solve” the problem? (Ref. your quote above) Since you are willing to go that far, just rip it all out, OSB & PB, and start from scratch. Glue and screw down 3/4 T&G plywood to joists, followed by 1/4 PB glued and fastened with ring shank nails. Problem solved…for a long, long time.

When I built my home 15 years ago, I went for overkill. I went 3/4 plywood glued and screwed, 1/2 plywood glued and ring shank nailed, 1/8 PB glued and nailed. My floors are as solid as a brick sheethouse to this day !!! No Deflection, no noises…ever. :smiley:


Good idea however as Jim stated earlier, the floor joists are 13+’ long and the room is some 31’ wide (as I read it). No matter what you use (2 x 10’s, LVL or steel) for a beam you’d need to install some columns to support them or they would sag, thus defeating the whole pupose.

I also can’t believe 2 x 10’s 16" o.c. spanning only 13’ would cause that much of a problem, JMO.

Gotta differ with you guys on the bridging and midspan blocks. They are anti-rotation devices and both have been known to squeak. The more metal (fasteners) to wood or wood to wood connections, the more opportunities for squeaks.