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subfloor for hardwood install

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  • subfloor for hardwood install

    I will be installing 3/4" ash hardwood flooring on the main floor of a townhouse (circa 1976). The subfloor is 5/8" plywood and was nailed to the 2x8" 16" O.S. joists. The floor is a bit bouncy and squeaking in some places. I plan to put in some sister joists and blocking in the basement below but aside from that what else would your recommend I do before laying down the hardwood? I would like the floor to be stiffer and without squeaks. I could screw down the existing plywood. I could add another later of plywood (1/2" or 5/8") and glue and screw that down (about 450 square feet). I welcome your suggestions.
    thanks,
    Andrew

  • #2
    Re: subfloor for hardwood install

    My only real concern is if you add another layer of sublfoor, you will have issues with the transition into other rooms. Most certainly I would recommend screwing the existing plywood to the joists for eliminating the squeaking. How is the floor bouncing? Is the plywood flexing between the joists, or are the joists flexing as well? If the joists are flexing, I would suggest setting a beam mid span instead of sistering on new joists. If the plywood is flexing between the joists, you can glue and screw more plywood to it, that will make it bomb proof. An alternative to screws is to use a crapload of 1 1/4" medium crown staples. Installation is a TON faster with staples unless you have a self feeding screw gun.
    We don't have preventative maintenance around here, we have CRISIS MANAGEMENT!

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    • #3
      Re: subfloor for hardwood install

      I have a quick drive 3ft. stick screw driver. If You don't own one rent one and screw down the Ply. NO new ply. From the basement,Add solid blocking 8 Ft. on center between joists. Use sub floor adhesive with the BIG CAULKING GUN,and run a bead from underneath on one side of each joist and Ply joint. Use red Rosen paper stapled over ply between hardwood. Red Rosen paper eliminates squeaks.
      Your floor will be rock solid and quiet. Good Luck
      I can build anything You want , if you draw a picture of it , on the back of a big enough check .

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      • #4
        Re: subfloor for hardwood install

        MB, Thanks for the reply. There will be no issues with transition to other rooms since it only has to transition to a 40 square foot foyer and I will build that up appropriately to get an even transition. I think the bouncy floor is caused by flexing plywood and flexing joists. This based on viewing from below while my nephew jumps up and down on the floor above. The mid span beam is a good suggestion but I am reluctant to affect the headroom in the basement with that solution unless I have to so I am looking at other options. The span is only 10' so I would have thought the 2x8 16" O.C. would have been more effective. The medium crown staples would be quicker but I am inclined to go with screws for the holding power which I think helps eliminate the squeaks. I don't mind spending the time or the money, I just want to get it 'right'.
        I appreciate your input,
        Andrew

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        • #5
          Re: subfloor for hardwood install

          Originally posted by toolaholic View Post
          I have a quick drive 3ft. stick screw driver. If You don't own one rent one and screw down the Ply. NO new ply. From the basement,Add solid blocking 8 Ft. on center between joists. Use sub floor adhesive with the BIG CAULKING GUN,and run a bead from underneath on one side of each joist and Ply joint. Use red Rosen paper stapled over ply between hardwood. Red Rosen paper eliminates squeaks.
          Your floor will be rock solid and quiet. Good Luck
          Thanks for the replay toolaholic. I read in a FHB article that blocking isn't that effective but I think blocking makes sense and I intend to do it. So, the paper helps with squeaks - good to know. Your input is appreciated!
          Andrew

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          • #6
            Re: subfloor for hardwood install

            Sorry, that's incorrect info about blocking! I've been a carpenter 49 Years Blocking adds great strength to floors! When You step on 1 joists ,the ones on either side help take the load. In the U.B.C. Blocking shall be no less than 10 ft. On Center.
            I can build anything You want , if you draw a picture of it , on the back of a big enough check .

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            • #7
              Re: subfloor for hardwood install

              What we do when don't have transition issues is : remove all the existing nails ( they are causing your squeeks ), put PL premium on existing floor, top with 3/4" advantech, screw with 3" screws ( do not use drywall screws) into the joists 6" on the perimeter & 8" in the field ( you can get by with 12" in the field). If time is not an issue & you want make sure you do it right get a countershink bit with a pilot bit, because you want make sure all the screw heads are not sticking up & cause you problems with your hardwood floor. If you still have a bounce you can sister up the floor joists & add blocking. We have never had a floor fail the BIG BOY test ( 300+ .lb carpenter jumping up & down ).

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              • #8
                Re: subfloor for hardwood install

                Mr. Fudd,

                Removing all the nails? I was hoping you wouldn't say that
                Do you have This would be hundreds of nails, and I wonder if I will do more damage to the plywood and erase any benefit.
                What if I just drove in screws in adjacent to the loose nails?
                If removing nails is the only way to be 100% confident then I'll do it. Any tool you'd recommend other that by claw hammer?
                One more thing, when I glue and screw down that second layer of plywood/advantech do you recommend I screw into the joists? A guy on another forum was quoting the building code (I forget the location) where they recommend the first layer gets screwed into the joints but the second layer is only glued and screwed to the first layer but recommends avoiding the joists.
                Thanks,
                Andrew

                Comment


                • #9
                  Re: subfloor for hardwood install

                  Avoid the joints?? Why on earth would you avoid fastening the joints?? When attaching the second layer, fastner location is less important or critial than on the initial subfloor. I would run my sheeting cross ways and avoid having my seams lining up with seams below if at all possible. For removing existing nails, I would invest in the following.





                  These three tools plus a block of wood will pull the nails with ease.It sounds like pulling nails is not your cup of tea, yes you can just add screws to existing joists, and set the existing nails, that will stop the squeaks for now, but no guarantee they wont come back. With the right nail puller (the largest one you can buy) pulling all of the nails in the floor will take less than 2 hours if you are slow, an hour or less if you are fast. You can do it wrong twice, or right once.
                  We don't have preventative maintenance around here, we have CRISIS MANAGEMENT!

                  Comment


                  • #10
                    Re: subfloor for hardwood install

                    Originally posted by athuswal View Post
                    Mr. Fudd,

                    Removing all the nails? I was hoping you wouldn't say that
                    Do you have This would be hundreds of nails, and I wonder if I will do more damage to the plywood and erase any benefit.
                    What if I just drove in screws in adjacent to the loose nails?
                    If removing nails is the only way to be 100% confident then I'll do it. Any tool you'd recommend other that by claw hammer?
                    One more thing, when I glue and screw down that second layer of plywood/advantech do you recommend I screw into the joists? A guy on another forum was quoting the building code (I forget the location) where they recommend the first layer gets screwed into the joints but the second layer is only glued and screwed to the first layer but recommends avoiding the joists.
                    Thanks,
                    Andrew
                    Every nail you leave in will be a potential squeeker. I would remove them all. The tools Masterbeavis recommended will work just fine. You can also get a good set of knee pads (ones that don't fall down to your ankles every 5 mins.) or a knee board. You need to screw into the joists, because you are not going to screw the the first layer to the joists before putting the 2nd layer on. Also like Masterbeavis said avoid the 1st & 2nd layer seams from lining up. Also before you put the second layer down mark on the bottom of your walls where the joists are, so you can pop a chalk line on the 2nd layer.

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                    • #11
                      Re: subfloor for hardwood install

                      Originally posted by MR.FUDD View Post
                      You need to screw into the joists, because you are not going to screw the the first layer to the joists before putting the 2nd layer on. .

                      Don't you mean you are not going to screw the first layer to the joists AFTER you apply the second layer??
                      We don't have preventative maintenance around here, we have CRISIS MANAGEMENT!

                      Comment


                      • #12
                        Re: subfloor for hardwood install

                        Originally posted by masterbeavis View Post
                        Don't you mean you are not going to screw the first layer to the joists AFTER you apply the second layer??
                        What I was trying to say is after you remove all the nails from existing sub floor you do not have to screw it to the joists before putting down the 2nd layer. Just put PL premium on the existing sub floor & screw both layers to the joists with 3" screws.

                        Comment


                        • #13
                          Re: subfloor for hardwood install

                          Ah, ok, you were describing taking a labor shortcut without fully describing the shortcut...
                          We don't have preventative maintenance around here, we have CRISIS MANAGEMENT!

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