I don't think a video will convince me of purpose or the point,lol

I believe that if you join 2 solid 2x4's together, it's stronger than a 4x4. I don't see this with 2 cross grain construction thickness's, adding up to the total of the same cross grain thickness. Especially stapled with a fastener that has 1/4" of grab,( surely less grab than that of the thickness's glued and pressed). Infact I believe if anything this compromises a solid layer of 3/4".

The OP mentioned "2 layers compensate for floor varience better than a single layer". The existing substrate varience is what it is, until you address that issue. If not within spec, the 2 layers are not changing that. It may be giving you a false sense by walking on a waffle of 2 layers, but it's not making the problem better than 1 layer of the same thickness .

Well I ain't impressed with what the NWFA says anyway. heh heh. Lots of strips of 3/4 laying on the ground not conntected to anything does not sound like a solid floor to me.

...."The OP mentioned "2 layers compensate for floor varience better than a single layer". The existing substrate varience is what it is, until you address that issue. If not within spec, the 2 layers are not changing that. "

I refer to a small variance in the floor , had to remove 2 layers of tile and grind down the slab to remove excess thinset . small peaks and valleys from grinding but within tolerances ,. the two layers on 3/8 overlap seem to smooth that out . like the quote below i dont like the idea of simply laying strips of 3/4 plywood down and letting the 3/4 wood floor make it a cohesive unit .

.... " Well I ain't impressed with what the NWFA says anyway. heh heh. Lots of strips of 3/4 laying on the ground not conntected to anything does not sound like a solid floor to me. "

can anyone give a opinion on staples ( 1/4inch crown x 5/8 ? ) , also was gonna use a very light application of gorrila glue ( expanding urethane ) between layers and keep the wood boxes on it over night . i am no stranger to carpentry , that being said , this aint no book case either and i have seen amateur book cases built by friends and if any of you can relate my wife would never let me live down an ugly book case.

i really appreciate you all coming back with your input . i dont do this everyday and i can imagine a 100 ways of doing it wrong and only a few that are right .

in reading the forums here and elsewhere as well as discussing with some in the biz , i find that hardwood over concrete is situation specific and cant be one size fits all . if the economy were better i would hire a pro , but after reading some posts here i dont think some of the ones i have talked to locally are likely to do anything but screw the job and get me divorced . i can tell you for sure that most guys calling themselves flooring professionals in south florida dont know a dam thing about hardwood over concrete and have never heard of the NWFA . a few might but they are the ones i cant afford .

so i am pretty settled on :
2 layers of 3/8 stapled and glued together floating over 15 mil paper overlapped and 6 mil plastic w/ tapcons at the thresholds . then 2" staples into 3/4 oak w/top nail top/secret nails and some glue at beginning/ends and thresholds . all finalized with the wife's base of choice ( this part i do very well , she is a baseboard and crown molding nut ) .

if anyone sees a tragedy in my approach your input would be priceless to me. thanks.

I told you what I use above, the 7/16 crown with the 5/8 leg , 16 ga are not easy to find. Shoot in at an angle and counter sink.

I've been meaning to address your tapcons at the thresholds. You do not want to lock in a floating floor system. So don't do that unless your going to tapcon the whole shebang.

Also use the 6 or 8 mil plastic on the slab first, then the 15lb paper if you want. I like the paper on top of the plywood.

IMO the best install for a floating plywood subfloor/underlayment for hardwood flooring IS...... roofing mastic or Bostik MVP4 troweled on using the trowel bostik specify's, I think it is a 3/16 x 5/32 V notch, for either one. That goes down first, then six mil plastc ( do this in 3 to four foot wide shots across the room for ease of plastic installation) and then the plywood, then the roofing felt. It is basically the old NOFMA fastened plywood over concrete installation except if your fastening to the slab you should use two layers of mastic and two layers of plastic. That way the fasteners that puncture the vapor retarder get sealed up.

I's really not that much more work than a single layer of 3/4 plywood when you take into account all that ripping of the 3/4 into what...18 ich wide strips? That sounds nuts to me.

Quote:

I told you what I use above, the 7/16 crown with the 5/8 leg , 16 ga are not easy to find. Shoot in at an angle and counter sink.

looked for 16 gauge , bigbox stores no go (16 gauge stapler, yes , but 5/8 long staples that work in it and are 16 gauge, no , , that why i was leaning toward the urethane glue between sheets and 18 gauge . can suggest a stapler for 16 gauge that has 5/8 long available ?



was gonna do the front door threshold ( 36 inches ) , and a transition to tile in a dining room ( 8 feet ) . they are on opposite sides of a 20 room ( say east to west ) running with the wood , was not intending to lock down the plywood anywhere else .what are the concerns in this ? can it raise up/expand with this approach ?



i thought the idea of 15 paper down first was to stop the slab from rubbing a hole in the plastic . ??

as for mvp or any mastic glue or adhesive . i have too pass . i am all for over kill , but i helped out another amateur one time and the mess was never ending .




here i agree with you , and dont forget the suggested kerf cuts into the wood every 12 inches before you cut it into strips. i would have to see that done before i could begin to understand the benefit . ( NOT THE KERF CUTS , BUT THE 18 STRIPS )

so again, why the big concern about fastening the down the float at a couple of points of concern ? can you elaborate ?

thanks

Yea, anytime you lock down a floating floor and underlayment it will buckle up unless the whole floor is fastened down. It needs to be able to move freely.

And actually the MVP4 is not that bad. You can do the whole floor, come in the next day and it is all set. Can be kinda tacky so rolling out plastic and be a slight hassle. It depends on how long you let the MVP4 set up and the humidity. More humidity helps it set better, less tacky.

I'm certain Howard would agree.

Sometimes you need to think outside the big box

http://www.google.com/products/catalog? ... DIQ8wIwBA#


http://www.amazon.com/Anchor-6605PG-10M ... B0024NKL7I

Oh Yea, I'm just taking this interesting process all in Keeping to myself......for now.

Two thumbs up for thinking outside the box!

I do this for this very thing! Peace of mind!

so the paper is first ? , can anyone contribute to my ( now ) concern of attaching my floating subfloor at the thresholds .??

as a side line home depot is blowing out some pneumatic tools ( some with ridiculous shipping charges , but most not . ) . hope i am not violating any rules by throwing this in . its still on topic since the 16 gauge nailer was talked about .. thanks for any input


Senco SKS M12-M17 Pneumatic 18-Gauge Strip Stapler
Model # 300152N Internet # 100617635
$76.00/EA-Each Ships FREE with $249.00 Order

Senco Roof Pro 455 XP
Model # 3D0101N Internet # 100615075
$74.75/EA-Each This item does not qualify for free shipping.



Senco SNS44 XP Pneumatic 16-Gauge Strip Stapler
Model # 3B0101N Internet # 100617636
$74.75/EA-Each Ships FREE with $249.00 OrderOnline Special Valid: 12/23/2010 - 01/05/2011
http://www.homedepot.com/h_d1/N-5yc1vZ1 ... ogId=10053


Senco FinishPro 32 16 Gauge Finish Nalier
Model # 1X0201N Internet # 100615089
$34.75/EA-Each Ships FREE with $249.00 OrderOnline Special Valid: 12/23/2010 - 01/05/2011


Bostitch Strapshot Metal Connector Nailer
Model # MCN150 Internet # 100536502
$54.75/EA-Each Ships FREE with $249.00 OrderOnline Special Valid: 12/23/2010 - 01/05/2011


PORTER CABLE 1-Nailer & Compressor Combo Kit
Model # PC1PAK Internet # 100672205
Store SKU # 977509
$95.60/EA-Each This item does not qualify for free shipping.Online Special Valid: 12/23/2010 - 01/05/2011


PORTER CABLE 18 Ga., 1-In Narrow Crown Stapler
Model # NS100B Internet # 100672215
Store SKU # 222708
$22.25/EA-Each Ships FREE with $249.00 OrderOnline Special Valid: 12/23/2010 - 01/05/2011


DEWALT 21 Degree Full Round Head Framing Nailer
Model # D51850 Internet # 202188241
$71.25/EA-Each
This item does not qualify for free shipping.OrderOnline Special Valid: 12/23/2010 - 01/05/2011

Paslode F275C Coil Master 15 Degree Pneumatic
Model # F275C Internet # 100609901
$96.25/EA-Each This item does not qualify for free shipping.Online Special Valid: 12/23/2010 - 01/05/2011

Not so sure the floating plywood is going to move that much. But yet another reason to trowel on a vapor retarder like MVP4 first.




Thresholds or reducers and transition strips?

FYI- I am bidding on a job right this very minute where the owner had a guy come in and glued 3/4 beech, 5" wide to the concrete. It was pretty ugly but he is going to try and keep it in some little room. I doubt it will stay as many planks are already peaking at the long seams and has maybe a quarter inch expansion at his floor to ceiling windows. Heat is not on.

So on the big living room I am (if he accepts my bid) do the two layers of 3/8 with plastic and MVP4. One wall has 3 feet of fill in back of it and the water cascades down the mountain when it rains with no french drain....where does that water go. Whatwas the architect thinking? It's up against a mountain so that makes it a below grade install anyway. Gotta take extra precautions.

Please help…

I am planning to do about 220 SQ feet of 3/4” solid cherry over a concrete slab and another 500 SQ ft over a wood subfloor.

Over the concrete; I was planning to do:
- MPV4
- 6 mm plastic
- ¼” Foam taped on seams
- 3/8” plywood
- Another layer of 3/8” plywood layed 90degrees to first layer glued together (please provide recommendation for glue) and stapled
- 30 lb felt
- ¾” Cherry with lots of staples

I would appreciate any feedback:
- Is MPV4 the right product to use? Is there a less expensive alternative?
- Do I need the 6 mm plastic if I do MPV4? If I do 6 mm plastic is there a particular tape to tape the seams?
- Is the 1/4” foam a bad idea? I am thinking it will absorb some small surface issues in the concrete (compress around high spots)
- Would I be better off using ¾” plywood or OSB on top of the foam and securing with Tapcon’s? I assume if I use tapcon’s I need to drill into the plywood so the head sits sub flush
- On the OTHER part of my floor which is on a plywood subfloor, I was planning to add a ½” OSB on top of existing plywood and screw down to the joists, reason is to bring the floor up a bit to match what I am doing on the concrete portion. Is this a bad idea?
- In some posts people were talking about scoring or cutting down the plywood so it would conform to the surface. Is this necessary?

Thank you for taking the time to read and respond!!!!

i too am curious how the experienced installers here will reply . i am doing over 1k ft and the idea of putting that many tapcon to hold down the plywood pushed me toward floating the subfloor . my concern now is the two threshold points that i feel i should attach with tapcons , but it seems some here say thats a bad idea if i am floating the rest of the subfloor . was hoping fro some experienced input .. thanks

Yup, that's the bottom line, like SP said earlier.

Thresholds are anchored. They are not flush cut transitions. They are overlap, so the floor floats under them.

Custom milled for height needed.