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Raising a wood floor

| Posted in Construction Techniques on October 2, 2004 06:16am

Well, it’s not quite like the title sounds.  I had a discussion going a few days ago about putting a wood floor over a concrete porch slab, and got reasonable advice.  But the specs have changed a little.

The concrete porch is 5 inches lower than the kitchen floor, and the client wants them to be close to even.  So … 3/4″ floor + 3/4″ ply subfloor leaves 3-1/2″ to fill.  I like the idea of filling the gaps between the sleepers with foam.  Would you use a 4×4 sleeper?  Or stack two 2×4’s?.  What about running two layers of 2×4 at right angles, and still filling the gaps with foam?

 

Whenever you are asked if you can do a job, tell’em “Certainly, I can!”  Then get busy and find out how to do it.  T. Roosevelt

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  1. fredsmart48 | Oct 02, 2004 06:35am | #1

    The last time I measured a 2 x 4 it was 1 1/2 x 3 1/2 so if you lay the 2 x 4 on it's side and stack you have 3 inches in height. You will still need 1/2 inch.   Why do you think you need 3 1/2 inch nailing service

    1. FastEddie1 | Oct 02, 2004 08:08pm | #2

      Why do you think you need 3 1/2 inch nailing service  Not sure what you mean by that.  What I'm trying to do is find the best way to raise the finished levelk of the floor to +5".

      Whenever you are asked if you can do a job, tell'em "Certainly, I can!"  Then get busy and find out how to do it.  T. Roosevelt

      1. User avater
        JeffBuck | Oct 03, 2004 03:01am | #3

        uhhh ...

        3 1/2 ...

        +

        3/4 ....

        +

        3/4

        ?

        the 4x4 is gonna be 3.5 tall ... and wide. He was asking why U need 3.5 wide ... to nail the 3/4 ply to. Why not a 2x ... and nail the 3/4 ply into the 1 1/2 edge ... like any other floor.

        JeffBuck Construction, llc   Pittsburgh,PA

             Artistry in Carpentry                

        1. FastEddie1 | Oct 03, 2004 05:22am | #4

          ... like any other floor.  Never done this before.  The "answer" is probably painfully obvious, and will be clear as mud when I'm finished, but at this point in the project I'm struggling for help.

          Had a thought after I posted the Q ... Just frame a series of 2x4 "floor joists" complete with blocking, and fasten the ply on top.  One of my initial concerns was the tendency of a vertical 2x4 to roll over, whereas a 4x4 would be more stable.

          Whenever you are asked if you can do a job, tell'em "Certainly, I can!"  Then get busy and find out how to do it.  T. Roosevelt

          1. User avater
            JeffBuck | Oct 03, 2004 07:07am | #5

            a framed floor is just like a wall .... the end plates are .. or band/rim joists ...

            and simply top and bottom plates ..... but the "wall" is laid down.

            just lay the peremiter boards .... then infill every 16oc with the joists ...

            I'd lay a nice bead of PL adhesive first .. then set the 2x framing into place.

            coupla angled toenails if you can't get to the egdes to nail thru ....

            The sheath with the 3/4 ply.

            the toe nails are just to keep the joists from rolling as ya sheath.

            after U sheath ... and once the glue sets .... you'll have a rock solid dance floor.

            are U going to need a VB or insulation in the mix somewhere?

            JeffBuck Construction, llc   Pittsburgh,PA

                 Artistry in Carpentry                

          2. FastEddie1 | Oct 03, 2004 04:47pm | #8

            Jeff, here's a link to my first discussion on the porch floor ...

            http://forums.taunton.com/n/mb/message.asp?webtag=tp-breaktime&msg=48072.1

            As someone noted, I may have to scribe the joists to get a level floor, but otherwise what you describe is what I will do.

            Whenever you are asked if you can do a job, tell'em "Certainly, I can!"  Then get busy and find out how to do it.  T. Roosevelt

          3. DANL | Oct 03, 2004 04:06pm | #6

            From what I heard earlier from others here, is that 4x4's tend to be twisted because they are often cut from the center of the tree, so 2x4's would be better. They won't roll after you put the sheathing on, but you could put blocking between them down the center of the room, or anywhere else where you'd like to have a nailer to support edges of sheathing. Styrofoam between sounds good.

          4. mikerooney | Oct 03, 2004 04:42pm | #7

            If that floor was originally a porch, it'll be pitched away from the house. You'll have to shim it level. 

          5. Piffin | Oct 03, 2004 04:51pm | #9

            Ed,

            I have done this with PT 2x4 frame laying directly on the slab, except that at the perimeter, I use 2x6 ripped to fit the slope, and shimmed under midspans for extra suipport. In that case, there was no need for insulation, but I suppose FG or faom could be inserted between.

            My idea here, since insulations seems important is to frame a band joist perimeter of 2x4 PT ( if slab is level) and then infill with 2" DOW blue foam over entire slab, and then lay 2x4 sleepers flat across the foam nailing into the band joist to hold them in place. I did something very similar to this on a raise wood deck being converted to interior space. The space between sleepers served to allow for runs of heating PEX 

             

            Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

          6. FastEddie1 | Oct 03, 2004 10:10pm | #10

            Pif, you're saying a framework of 2x4 on the flat, fill with foamboard, then a framework of 2x4 on the flat at 90 degrees?

            What about a vapor barrier?  Where in the sandwich would it go?

            Whenever you are asked if you can do a job, tell'em "Certainly, I can!"  Then get busy and find out how to do it.  T. Roosevelt

          7. FastEddie1 | Oct 03, 2004 10:37pm | #11

            Another part of my puzzle.  The attached rendering shows roughly what is involved.  There is an existing concrete porch slab with a small landing and a ramp to grade.  I'm going to add a wood floor about 5 inches higher.  They have a handicapped child, so creating a step at the doorway is not a good idea.  The existing posts will remain (4x4 at about 5 ft o.c.) and will be filled with windows ... and a door.  How would you terminate the wood floor at the doorway, and how to add 5" to the landing?

            I'm thinking about setting anchor bolts into the top of the landing, form and pour a 5" cap.  Should I just terminate the new concrete flush wiht the posts?  I was going to go close to the end of the ramp, saw and chip a recess so it doesn't feather to zero, and pour a topping on that as well.

            Yes, there is currently a 5" step between the porch and the kitchen, and I don't know how they handle that.  One of the reasonms for this project is to make it as wheelchair-friendly as possible.  Interesting situation ... the father is a doctor, the mother is a nurse-turned-mother, and the 5 YO boy has brittle bone disease.  You can literally break his bones just by picking him up.

            Whenever you are asked if you can do a job, tell'em "Certainly, I can!"  Then get busy and find out how to do it.  T. Roosevelt

          8. Piffin | Oct 04, 2004 01:56am | #12

            Nope, the foam is continuous and the framing 2x4s lay on the flat over it, except at perimeter where they stand on edge like a band joist normally does. The interior portion of the framing is sleepers over the foam so you have 2" foam plus 1-1/2" sleeper for 3-1/2" framimng then your 1-1/2" of sub floor and finished floor equals 5" total 

             

            Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

          9. FastEddie1 | Oct 04, 2004 03:18am | #13

            A question born of ignorance ...  The foam is obviously strong enough to support the live & dead loads, right?  Any problem with squeeks?  What about a vapor barrier?

            Whenever you are asked if you can do a job, tell'em "Certainly, I can!"  Then get busy and find out how to do it.  T. Roosevelt

          10. Piffin | Oct 04, 2004 05:41am | #14

            EPS foam IS a VB.

            Squeeks ( just blame the mice, LOL) I think that we laid a ply of paer over the foam and under the sleepers, but can't remember now. But no complaints and i don't remember hearing any squeeks. For insurance, you could always use spray foam to glue down the sleepers and foam to crete connection as well as sealing the butt joints in the foam sheets themselves. That would also grant you a better VB too.

            Yes it is strong for spread out loads like this. Remember, it is used under concrete slabs for insulation. Your only loads on it will be the flooring and live laods there. The walls would load on the perimeter, transmitting load of roof, wind, walls, etc to the slab directly and by-passing the foam. 

             

            Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

          11. FastEddie1 | Oct 04, 2004 06:52am | #15

            Muchas gracias senor.

            Any thoughts on adding concrete to the ramp?

            Whenever you are asked if you can do a job, tell'em "Certainly, I can!"  Then get busy and find out how to do it.  T. Roosevelt

          12. Piffin | Oct 04, 2004 07:01am | #16

            Form it up and pour it.

            What did you do with the real Ed Hilton?

            You seem off your game today.

             

             

            Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

          13. FastEddie1 | Oct 04, 2004 03:35pm | #17

            In a bit of a funk. 

            But, I find it much easier to give advice on other projects than my own.  Somehow, when it's me looking at doing the work, everything takes on a different perspective.

            Whenever you are asked if you can do a job, tell'em "Certainly, I can!"  Then get busy and find out how to do it.  T. Roosevelt

  2. csnow | Oct 04, 2004 09:23pm | #18

    You will probably want some sort of moisture barrier between the masonry and the wood to prevent 'rising damp', and condensation.  Think of concrete like a big sponge.

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