I’m ripping up wall to wall carpeting and replacing with 3/4″ X 2 1/4″ t&g red oak. The subfloors are 3/4″ Plywood. They have construction adhesive and nails. I have added screws to supplement the nails. The room I am working in is on the first floor over an unfinished basement. There is a t&g joint that runs perpendicular to the joists and squeaks pretty much along its entire length. I tried working talcum powder into the joint but this has only helped a little. I’m thinking I should brace these joints from below. What’s a good material to use and fastening technique? I was thinking pieces of 2 X 4 between the joists bridging the t&g joint. Screws from below through the 2 X 4 into the subfloor and screws from above through the subfloor into the 2 X 4’s. Construction adhesive? Overkill? Lay the flooring and see if this tightens everything?
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I can't say that it's correct, but I've used wood glue (eg, Titebond) in the T&G joiints in such situations in this house.
Get it fixed before you lay the flooring.
Wood Glue in T&G Joint
Interesting idea. Do you think the glue will hold if the joint isn't tight or maybe it'll just act as a cushion and keep the wood from rubbing?
In the couple of cases where I used it the joint was not particularly tight. (The only thing that was "particularly tight" about our house was the builder.)
In one case I actually injected the glue through vinyl flooring with a syringe. In the other case the carpet had been removed, so I just squirted it into the joint.
But my experience is limited to those couple of cases -- they've held & kept quiet for 20-30 years -- and I have no idea if that is typical or not.
There should be gaps
All plywood joints should be installed with 1/8" spacing or "gaps" per manufacturer specifications. If structural sheating was installed tight, then it was installed wrong. This spacing includes all butt joints and running joints (including T&G). If you're able to squirt glue ithrough a vinyl floor with syringe and into a joint, then it's the wrong glue to be used for a Glued Subfloor System.
If it worked somewhere to solve a squeak, then you were just lucky.
use the right glue
"wood glue" is a rather unspecific term. Titebond makes many different type wood glues.
Gluing subfloor structural underlayment is a good idea. According to Georgia Pacific an APA rated Glued Floor Systems are "so strong that floors and joists behave like integral T-beam units". Further, " "Gluing helps eliminate squeaks, floor vibration, bounce, and nail poping".
These system involved glue between the plywood and joists and also involves gluing the tongue and groove joint. It should be noted that plywood must span two or more joists to meet span rating printed on the sheets. The glue used must also meet ASTM D3498 or Performace Specifiication AFG-01.
Ohio Sealants Inc. (OSI) makes a very good subfloor adhesive called SF-450. It meets the Glued Floor System requirements. It is not reg. carpenter's yellow glue (aliphatic resin), but rather a sythetic rubber & resin based glue. This is what I use. I believe most lumberyards--and the even the big box stores-- carry it.
Block away mate
If you're going to reinforce a potentially unglued T&G joint with 2x4's (not a bad idea), then I would recommend the following installation.
Install blocking flat ways (3.5 side horizontal), librally glue the face going against the existing subfloor with OSI SF-450 and then pockst screw the ends with wood screws into joist sides. If you can pressure fit the length where you can go upstairs and screw through plywood into 2x4's from above (definitely not from 2x4 into subfloor), then run your joist screws you'll get the best fit to the joists and risk less glue "bridging". Or have a helper screw from above while you glue and fit blocks from below. I find that the most effecient way to tackle this kind of task.
BTWI wouldn't use any nails for your remodel task. Matter of fact, pull any nail you see in subfloor and replace with a screw. Screws are helical wedges. They have tremendous holding power (if you use the right ones) and don't squeak because they really can't rub against anything.
Blocking
I'll do the pressure fit. I've got some PL Premium Construction Adhesive...is this ok to use? I'll screw through the subfloor into the blocking. Then pocket screws through the blocking into the joists. Just out of curiosity why shouldn't screws be driven through the blocking into the subfloor?
Blocking
I'll do the pressure fit. I've got some PL Premium Construction Adhesive...is this ok to use? I'll screw through the subfloor into the blocking. Then pocket screws through the blocking into the joists. Just out of curiosity why shouldn't screws be driven through the blocking into the subfloor?
Thought you might ask that.
I avoided it in my previous post because I find it tougher to explain in words (rather than illustrate in the shop).
But I'll give it a shot:
1. As a general rule, it's not a good idea to screw thicker material to thinner material. With screws, the idea is to "clamp" one material to another. To achieve the best clamping pressure you don't want the screw, or helical wedge, to catch on the material you're pulling through as your screw grabs the material you're anchoring to. When this happens, you get whats called "screw jacking". You actually start to force the materials apart instead of together...that or the threads strip out of the anchoring (to) material before they strip a clearance hole in the 2x (through) material. This is why it is a good idea to have a clearance hole through the material your clamping through...and why many wood screws have a partial smooth shaft toward the torquing head.
2. Even if you pre-drilled a clearance hole through the 2x, you only then have 3/4" of plywood material (with which to develope torque or wedging power) before the tip pokes up through the floor. It can be done (and sometimes one has to because of limited access), but the clearance hole needs to be correct and the screw length (and set depth) need to be just right. And even if all that i just right, you could still strip out easily; particularly if you hid a void area in the plywood. Why engage in an "iffy" proposition when you don't have to? It's much easier (and forgiving in terms of screw lenght and set depth) to attach the thinner plywood to the thicker 2x from up top.
Make sense?
Makes Sense
Makes perfect sense. Thank You for taking the time to provide a thorough explanation.
Deadnuts
I tried blocking a couple of bays but the squeaks didn't go away. I then pulled some of the nails and the squeaks were gone. They used bright shiney common nails.....nice guys. I had added screws between the original nails but apparently that wasn't enough. Well anyway, I've started pulling the nails and replacing with screws. I used Spax #8 2" between the originals and I'm using Evercote #8 2" decking screws in the nail holes as they are slightly thicker than the Spax. These screws correct? I've installed the hardwood in 7 other rooms and none had squeaks like this room....I had to pull some bent nails in the other rooms and I believe they were ring shank or at least I hope so.... too late now.
Those new fasteners are fine.
Yep. Those screws will work fine. Like I said, pull every existing sub floor nail in sight and replace it with a screw It might be a P.I.T.A., but if you think of like every nail your pulling is like elimiating a potential squeak, then it's easier to handle.
The other thing to remember is that you can't generate a squeak w/o deflection (movement). Adding the hardwood decreases deflection. So adding hardwood, in and of itself, reduces squeaks. Screws are just the icing on the cake.
Fasteners
One more question...just to beat it to death. The (pilot) hole left by the nail is slightly larger than the pilot hole that the charts indicate should be used in softwood.....that's why I went to the Deck Mate Evercoat which is slightly thicker than the SPAX. The (pilot) hole left by the nail is the pilot hole size that the charts indicate should be used in hardwood. Would I be ok using the SPAX or is the (pilot) hole too big for a good hold?
P.S. In fairness to the original builder I did find that they used a few spiral shank nails.
Fasteners
One more question...just to beat it to death. The (pilot) hole left by the nail is slightly larger than the pilot hole that the charts indicate should be used in softwood.....that's why I went to the Deck Mate Evercoat which is slightly thicker than the SPAX. The (pilot) hole left by the nail is the pilot hole size that the charts indicate should be used in hardwood. Would I be ok using the SPAX or is the (pilot) hole too big for a good hold?
P.S. In fairness to the original builder I did find that they used a few spiral shank nails.