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New Subfloor – Level Vs. Flat

chefwong | Posted in General Discussion on July 8, 2005 11:11am

Hi all –

 

I’m currently planning to redo the flooring in my house . It currently has 3/4″ planks for the subfloor. While I have yet to rip the different layers out – dining room floor is higher than the kitchen, etc , I am trying to decide how to redo the subfloor.

I’m planning to rip all existing flooring, etc so it will be down to the 3/4″ planks. Hopefully, this will bring me to a good level between the kitchen, dining room, etc. There currently is some dips but do to exisiting flooring, I’m not sure how Level it is from one end of the house to the other. So……I may just go for flat vs. level if the existing flooring is really bad.

I plan to use 3/4 BR111 solid wood flooring for the new floor.

I was planning to use 3/4 ontop of the exisiting subfloor and put #15 builder felt on certain areas if I needed to get floor more level.

– Should I be using T&G for this application or non, since it would be ontop of the exisiting subfloor

– On the new subfloor, fastening wise, should I fasten to the old subfloor or fasten to the exisiting Joists ?

 

TIA for your advice !

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Replies

  1. DeaDRingeR | Jul 08, 2005 11:39pm | #1

    Hey Alan

    How much does the floor dip?

    1. chefwong | Jul 08, 2005 11:49pm | #2

      I can't say for sure until I gut everything and see how the floor is with just the 3/4" planks.

      I suspect there's built up flooring on the kitch and possibly a 1/2 ply subfloor- 3/4" wood floor throughout the rest so it's hard to tell due to different flooring heights.

       

      1. DeaDRingeR | Jul 09, 2005 12:49am | #6

        If you have 1/4" dip it should be fine. When you get to the subfloor, screw down the old sub floor to the existing joist and remove any loose nails. Weither it be 1/4" or 1/2" underlayment it does'nt matter if you nail it or screw, I recommend 6" for the outside and 8" in the field, and of course use construction adhesive. If dip is more than 1" or above call me! ;) lol

        1. Nails | Jul 09, 2005 05:45pm | #7

          "When you get to the subfloor, screw down the old sub floor to the existing joist and remove any loose nails. Weither it be 1/4" or 1/2" underlayment it does'nt matter if you nail it or screw"

          We have done it the other way around, 2" staple down tight existing planks (staples work great with old planks that easily split) then screw and glue the underlayment,  being sure to as well hit the joists thru both plys.

          1. chefwong | Jul 09, 2005 08:46pm | #8

            I'm adding another 3/4 is because the floow is not level. There are dips , however I can't see how bad it is until I remove all the flooring.

            There is various underlayment/old flooring between the kitchen, dining room, etc so it's hard to gauge how good/bad the floor is currently. Nevertheless, I know the floor won't be level or flat by the time I rip everything down to just the 3/4 planks.

            I think I will just go for *flat* at the end of the day, and use #15 or #30 builders felt between the exisitng sub and the new layer to level out the dips.

          2. jrnbj | Jul 10, 2005 04:56am | #9

            I'd suggest you think long & hard about using another layer of 3/4 ply to "level out the dips"
            that way lies madness, except when you are planing on setting tile, & can use a self leveling underlayment after the 3/4 ply...
            If you have large dips, you need to see if you have sagging joists or some other structural defect causing them, before you go making youself crazy with strips of tarpaper & pieces of 3/4 ply.
            30 years doing this, I've never tried to level a floor using what is, in effect, a second, unneccessary subfloor.....

          3. JasonG | Jul 10, 2005 05:57am | #10

            I agree.

            I think its a waste of time and money to put another 3/4" over existing 3/4" plank subfloor.

            I have an old home which was gutted down the the floor system. I used the existing 3/4" pine subfloor. Filled in some low areas with self-leveling underlayment, then added plywood underlayment in prep for 9/16" hardwood.

            Not sure what kind of flooring you are going to install after all this, but if you are doing hardwoods, it is actually possible to take care of some dips in the floor sytem with regular ordinary shingles turned over with granules down to build up low areas confined to one area.

            The felt you mentioned is also a good idea.

            Just my two cents

          4. chefwong | Jul 10, 2005 07:08am | #11

            I think I may be phrasing it wrong. The 3/4" ply that I was planning to use was to be used as the underlayment for the wood flooring which is 3/4" solid planks.

            As far as deflection...that is still yet to be determined. I'm just going by what  I see but I can't really gauge the flooring until all the old stuff comes out.

          5. jrnbj | Jul 10, 2005 10:08pm | #12

            Hate to beat a dead horse, but hate even more to see someone waste time & money...per my earlier post, millions of houses have 3/4 hardwood over 3/4 decking (sometimes it's tounge & groove) with red rosin paper in between.....if you really feel the need for an underlayment, why the full 3/4 ? 1/2 or 3/8 will do just as well.....

  2. Shep | Jul 09, 2005 12:19am | #3

    30#  builds up the dips faster

  3. quicksilver | Jul 09, 2005 12:24am | #4

    Since you are tearing into it. You should do a careful inspection of the joist system if possible. Uneven floors can be caused by many things. From a previous owner removing a lolly column in the basement, to bad grading, to insect damage, to just stress on the floor causing the members to fatigue. If you can assess the situation and feel that there is no underlying problem that is going to cause you to have to tear back in before the new flooring warrants, and you can live with floors that are not level but flat I would choose flat. Especially if the discrepancy is not that much. I did a small house last year and the floors were out 2-1/4 inches from center to perimeter of the master and adjacent guest bedroom. We went level but maybe were willing to dig a little deeper than possibly your are.

    Always run plywood perpendicular to the joists, and nail into the joists. As far as T&G I would use it unless budget is so tight that it won't allow the extra dollars. I'm not sure though if it entirely necessary, as long as you made sure the edges were supported in all cases, meaning the sheet should never break on the edge of one of the planks.

    Remodeling requires one to be disciplined in making a decisions on where to stop and implementing them. Every remodel I have ever been on the house cried out to be completely redone. But in actuality it just not possible most of the time. Be careful. It is smarter and less expensive to ask questions and do research than it is to live with an inferior decision that t could have easily been avoided had it sat in the cooker a little longer. Good luck.

  4. jrnbj | Jul 09, 2005 12:24am | #5

    the 3/4 planks are the subfloor...millions of homes have T&G hardwood on 3/4 plank decking.....why do you want to add another layer of 3/4 ply on top?

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