Replies

1. 
   Guest_ | Nov 24, 1999 09:42am | #1

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   Rich, I had to do a floor just as you have described just about a year ago. The homeowners wanted a wooden subfloor to attach oak veneer flooring to. This was in a new home. We used 2X4 treated sleepers laid out on 16" centers shot down with Hilti pins, then we sheeted that with 3/4" tongue and groove plywood using lots of glue. I was not overly impressed with the finished product because you are at the mercy of your concrete guy with this method. If I had had the room I probably would have shot down perimeter sleepers and joisted with 2X4s so that I could have shimmed the subfloor straight where necessary. However the homeowners told me that the new oak floor went down fine with no complaints from the installer.

1. 
   Guest_ | Nov 24, 1999 10:14am | #2

   *Rich, Depending on how nasty the concrete is I would probably take the time to scribe the sleepers to the floor and/or shim as necessary before shooting them down permanently. Any moisture concern? Ralph

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   Guest_ | Nov 24, 1999 10:28am | #3

   *I install treated 2 x sleepers with stainless anchor bolts, countersinking the nuts. Lots more work, but holds so much better than glue and concrete nails.I install sleepers all around the perimeter, and across the room on the flat on 12" centers. I shim to get nice and even, then anchor them. I then install poly vapor barrier. This is absolutely necessary if working with wet treated lumber. I saw a flooring guy screw up once and installed the vapor barrier on the concrete, then installed the treated sleepers. The wood was wet. Trapped the moisture BETWEEN the slab and the subfloor. He had to redo all of it. Kiln dried treated lumber is cost prohibitive here, so I alsways get stuck with some really wet stuff. If you install the subfloor over the wet wood with no vapor barrier to protect the subfloor, moisture will accumulate on the bottom side of the subfloor. Worst case scenario is warpage and buckling of subfloor. Also produces mold and mildew.I really like tongue and groove subfloor, but AC fir works well too. It really depends on the floor covering, and whether or not I need a 3/8" or 1/2" underlayment for the finish floor. I've been known to use 3/4" CD plywood if a 1/2" underlayment is going down on top of it. This is becoming increasingly more popular as young couples buy or build houses. They are going back to traditional wood floors, or engineered wood floors. Just my thoughts...James DuHamel

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   Rich_Schutte | Nov 25, 1999 06:13am | #4

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   Thanks for the responses, but I guess that I forgot some extra information. The basement has a door connecting the garage and not really enough room to install sleepers. I'm not sure about nailing down wolmanized plywood ( or something else ), the hot water tank and furnace are in the basement and carpet will cover the subfloor.

3. 
   Guest_ | Nov 25, 1999 05:44pm | #5

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   Is this going to be a habitable room with the same floor level as the adjoining garage?

   Francis

4. 
   Bill_Guthro | Nov 25, 1999 10:11pm | #6

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   Rich - would the customer be interested in an acid stained or water-base stained floor? How about a stamped overlay in a pine plank pattern? There are many other cost-effective, durable and aesthetically pleasing decorative concrete options available. Best of all, the maximum change in elevation will only be 3/8". Worth considering.

5. 
   Guest_ | Nov 26, 1999 09:38am | #7

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   Rich,

   I recently saw one method that seems to work fine. Here is what the floor company did:

   First they swept the floor clean and trowled out a thin layer of roofing cement. (The thick kind, not the soupy kind) Then after it dried (or the next day) they put down a layer of 6mil clear poly on top of that. Then they cut and laid a layer of 3/4" plywood and shot it to the concrete floor. They had one "badass" nail gun for that. It's made for that purpose. It was so beat-up that I couldn't find a brand name on it, and the guy doing the installation didn't speak English, so I didn't find out where the gun came from.
   After that, they shot down the random width T&G Canary wood flooring. Beautiful floor. They did about 4000 square feet this way, and I haven't seem a problem yet. We used the same method in a small back entry hall on another job. Not having the special gun, we screwed the plywood down with tapcons. Worked great.

   The builder said that this floor company had been using this method for years with no adverse results.

   That's one method.

   Ed. Williams

6. 
   Rich_Schutte | Nov 27, 1999 08:48am | #8

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   Yes, the remodeled space will consist of a game room, bathroom and mechanical room.
   Rich

7. 
   Guest_ | Dec 01, 1999 10:31am | #9

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   It sounds to me that the customer wants the plywood subfloor , either to provide some relief from the concrete when walking on it or to be used for tack strips which hold down the carpet.

   Ijust did a similar job. That is a finshed basement that joins the rest of the house under the same conditions. I thinm that a ply would subfloor is altogether a bad idea. It will not provide any relief to the step if lain right over the concrete, its not an insulator , and tack strips can be nailed to concrete in different ways.

   The first thing I would do is make sure that there is no moisure coming up through the floor. Because you don't see a puddle of water doesn't mean that there isn't moisture. To do this, tape down a pieces of plastic in various spots and wait a couple of days. Right before a rain is good. If there is moisture coming through the floor, you'll see condensation under the plastic. If condesation is prsent, this must be fixed reguardless.

   Any noticable uneveness in the floor can be fixed with leveite or some other self leveling product sold at tile stores

   The money saved by not putting down plywood should be used for top qualitycarpet and matting for under the carpet (8lb)(the proper name escape me now, this is common for me).
   A good matting will surprise you. You may still be able to tell that you're walking on a harder surface, but this is really no different than if you were to put a subfloor over concrete. Again, this is because concrete floors have no give. Suspended floors flex

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   Guest_ | Dec 01, 1999 12:32pm | #10

   *we just did this and its done a lot in palm springs where there's a lot of water coming under the slabs from extensive watering.1: epoxy sealer2: three layers #15 felt w/ henrys mastic heavy between each layer3: min. 3/4" ccx ply w/ mastic and nails or screws4: #15 felt w/ mastic 5: hardwood floor nailed to the plyhope this helpsjohn

8. 
   Kevin_Adams | Dec 01, 1999 04:29pm | #11

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   I recently had a project where I ripped thin strips of treated 2X and used that in various thicknesses (1/4 to 1/2") to shim the sub-floor to an acceptable level. I used a powder actuated gun and glue to attach the strips to the concrete. Then I glued and screwed the plywood directly to the 2X strips.

   This method may not be ideal if you have a moisture problem, because the treated 2X material typically does not have chemical throughout.

   Another alternative could be to go with shimmed 2X4 joists and leave a "step down" area at the door. However, this could become an accident zone.

9. 
   Guest_ | Dec 01, 1999 04:35pm | #12

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   I saw somewhere a mesh-type product that can be laid down between the concrete and a floating plywood floor that you then lay your hardwood to, but I don't have info on it, does anyone know what this stuff is? Looks like Enkasonic mat, or the mesh product that's sometimes used under cedar shingles, or ridge-vent mesh.....

10. 
    Nathan_B | Dec 03, 1999 10:22am | #13

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    More often then not when finishing basements I don't install a subfloor. A recent customer requested a subfloor and I looked for a better way than strapping. There is a product available North of the Border, where I live and work, which is a hard plastic bubble wrap used for water proofing concrete foundations. The same product is available for floors called Delta FL or Home Depot has a Platon Membrane up here. This rolls out on the floor and you lay tongue and groove ply on top with a few tapcons to stop it from shifting. The pattern of the wrap allows for air circulation under the floor which is a big plus and very quick especially compared to strapping. Let me know if you can't get it there - there might be a business opportunity here. Nathan

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   flintin_ | Dec 10, 1999 10:46am | #14

   *I would lay 15lb fely outover the concrete and then shoot down 3/4" square edge ply. I had had alot of success with this method and have never had a problem with moisture perforating through

11. 
    Rich_Schutte | Jan 05, 2000 12:47am | #15

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    A client wants 3/4 plywood laid over the concrete floor, any tips to make this work well?