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Community and Q&A

Tongue and groove mishap

Mike M | Posted in Energy Efficiency and Durability on

So I installed my first row of T&G subfloor last night and screwed and glued it. What I didn’t realize was that I installed it with the tongue side towards the rest of the floor.

Rather than rip up the first row I decided to try and pound it in on the tongue side which is not easy nor fun. The only problem I’m running int is that I am not able to get all the the T&G’s to seat fully in the groove, instead they have the a 1/8″ gap or so.

Is this going to prove to be a problem later in the life of my floor? It is pretty solid right now. I was planning on putting a bead of caulk in the larger gaps are roll with it.

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  1. David Meiland | | #1

    Make a spline using a table saw, install it in the groove of your already-installed piece, and install the rest of the sheets the correct way.

  2. Mike M | | #2

    Are you saying just rip a notch in a 2x4 and slide that over to pound them in or completely flip the direction around?

    I already have about 18 sheets installed like this. I'm not very happy about the mess up, but if it will not cause long term issues I can sleep better.

  3. KEVIN ZORSKI | | #3

    "What I didn't realize is that I installed it with the tongue side towards the rest of the floor". It's unclear what this means. David interpreted it kind of the way I did, and his solution is good and practical.But you're reply leads me to think that both David and I don't get your problem. Re-post the question with a more thorough explanation of what the problem is.

  4. Mike M | | #4

    So I think what you and David are implying is that I can make a spline and install it between the grooves. That would not work.

    Right now the tongue side of the board is facing the side of the floor that is unfinished. I have to slide the grooved side of the new board into the tongue. The requires be to hit the tongue of the new board to seat the boards. Since the tongues are pretty weak, I have not been able to seat them completely and there have been small gaps. Not gaps that you can see through, but the tongues aren't completely in.

    I'm thinking of using an epoxy similar to what would be used to repair holes etc. that sets up hard. i can't feel a difference when walking on edges or in the field.

  5. Stephen Sheehy | | #5

    Are you using boards or tongue and grooved plywood? In either case, if you need to pound on the tongue, just rip a piece so you have a groove on one side and a flat side. Put the groove over the tongue and pound on the flat side. You'll deform the sacrificial piece, not the piece you are installing.

    It shouldn't matter whether the tongue or groove is toward one direction or another.

    What is the finish floor?

  6. Mike M | | #6

    I am using Durastrand T&G OSB The only reason the tongue side is a pain is you can't hit it nearly as hard. I tried the sacrificial piece and it didn't last very long as the two smaller edges spit.

    Finish flooring will be mostly laminate wood. One area will be tiled. I have to put 1/2" or more underlayment in to get the addition floor to sit flush with the original home

  7. Expert Member
    Malcolm Taylor | | #7

    Block under the joints on all the sheets you have down and switch directions for the rest of the floor.

  8. KEVIN ZORSKI | | #8

    Mike - It doesn't matter if the sacrificial piece does not last long. That's why it's sacrificial! Make a bunch of them. If you can make one from solid wood that may last longer. Or rip the tongue off one sheet and lay it down next to the last grooved sheet, then you can do the remaining sheets in the other direction. Your screwing and gluing so it should be fine. On that one joint where you reverse direction, you can install blocking as Malcolm suggests under that last edge that won't be tongue and grooved together to strengthen that joint. If this is not being laid over framing, but is laying over another subfloor, you don't have to worry about blocking the "change-over" joint, as it will be plenty strong being screwed and glued.The 1/8 inch joints are not worry worthy either, it may even be potentially beneficial to give the osb some room to expand should it get wet. Good luck on for project.

  9. David Meiland | | #9

    Professional carpenters never beat directly on the tongue when installing tongue and groove materials--we make sacrificial "beater blocks", as many as necessary, and beat on them instead. You would be better off with the groove side of your plywood facing the room, but unless you want to change directions, just put the glue in the groove side of a loose piece, then beat it into place using a beater block. If the OSB is not holding up, make some blocks out of solid wood.

    Malcolm's plan for changing directions is a good one... maybe do that? How big a room are we talking?

  10. Howard Gentler | | #10

    I always use oak T&G strip flooring pieces as beater blocks. They will last a long time even with the abuse. You can use them to pound in either the tongue or the groove.

  11. Mike M | | #11

    Everyone thanks for the help. It sounds like it is not going to be a huge structural issue. I am going to plan on blocking the ones with bigger gaps (there is not visible light gap, just not full engagement) and just finish up the floor.

    I will try beating them harder and cleaning up the tongues as I go. I also may try not putting in the last row of screws on the previous board as this seems to make it harder to start.

  12. Dan Kolbert | | #12

    Depending on how much you have left to do, Malcolm's suggestion makes sense to me. Just block under the next course so both sheets can be fastened into it, and then flip directions for the groove is facing out. The reason for the T&G is to prevent the sheets from moving at the seams, and the blocking will do it as well as the T&G. It is a pain and a waste of time trying to install with tongue out.

    Also, DO NOT fill the gaps. You're supposed to leave a bit of a gap anyway for expansion and contraction, and you definitely don't want to make movement difficult. You'll just create bulges or pops. Any flooring will either easily bridge the gaps or have a layer of underlayment first.

  13. Mike M | | #13

    Dan I've got about 12 more sheets to lay down today. I could rip the tongue of this last row and flip and block them as well. If I had more money and patience I would just rip it all off and restart, but I'm pretty sure that would destroy the TJI's below since I glued them all.

    After going out there this morning, the lumber must have been really dry. We generally sit in the 80+% in the summer outdoors. After a light sprinkle and sitting overnight, the gaps have already started to shrink up to where I'm not as worried.

  14. Andy CD Zone 5 - NW Ohio | | #14

    Yeah, no worries on the issue of an eighth-inch gap. Even if you install these things the other way around and beat the groove side senseless, you won't get t+g subfloor to be tight. Surely the manufacturer does this deliberately to save us builders from installing them too tight, which would eventually result in swelling at the joints and angry calls to customer service.

  15. Mike M | | #15

    I was able to get all of the boards seated much better/faster today using a longer beating block. The boards from yesterday seem to have swelled a bit and the gaps are now not too bad. I think I may still block all of the seams under the bathroom area to limit the deflection if weight was directly placed there. I have a bad tendency to think of a few thousands off as the difference between a happy machine and a corn-cobbed turbine, so to have an 1/8th gap was a lot. I keep telling myself an 1/8" in stick framed construction is normally nothing to worry about.

    Putting too much underlayment down will make my life difficult as I would have to then put it over the original slab on grade portion of the house (3300 sq. ft total) so I wanted a good subfloor. I was hoping to use a vapor barrior/slight insulation type underlayment under a floating laminate floor in about 75% of the house and just caulk any gaps that look to wide. There will be tile in two bathrooms and a kitchen that are now slab on grade, and tile in the master bath that will be over the addition. I have 3 extra joists in the bath area for under the whirlpool tub and shower. I figured a mud shower pan and an 80 gallon tub might need a bit of help. There will also be a mud base for the shower tile. The floor was designed with L/480 deflection over a span of about 16' before the LVL. At this they should be good for 63 PLF for live and 95 total. I hope that this will allow us to have a good tile floor (not natural stone). They should also be good for a 17'8" span with L/480 deflection and 40 PSF live load and 20 PSF dead loads.

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