First off, thanks to all of you more experienced folks that come along and answer these questions. I am a pretty good DIY person and a very experienced woodworker. I have done nail down floors myself, but always over a subfloor. For the first time, I have to deal with a concrete floor.

1) I want to avoid that "Pergo" like feeling. So I am nervous about a floated floor. I have read that some of the floated floors are less prone to "Pergo effect"? Should one put only a vapor/radiant barrier and forgo the insulation padding? Would that reduce the "drum" effect that a floated floor has?

2) I cannot nail down a subfloor, due to both height constraints as well as some pipes in the floor that are unmarked and could be damaged. I could do a "floated subfloor" out of built up layers of plywood, but I would have to use 2 layers of no more than 1/4", for 1/2 total height. And that seems too thin. And the cost adds up.

3) Glue down seems my only remaining option. Or have I missed something? I have done commercial vinyl installs (the 12x12 squares that you wax, that have no adhesive -- you trowel out adhesive, let it set up, then pop down the squares), so I can handle a trowel etc. Maybe I should go for it? Or should I hire it done?

Looking to use a square or micro bevel engineered product. Not looking at the long term, so I do not need a wear layer that will take lots of sandings. Floor is good concrete, on grade, no significant moisture issues. Climate is Kansas City -- cold enough to take radiant heat loss through the slab into consideration. The slab is NOT subinsulated, though it is vapor barriered apparently. Would like to avoid that "cold room concrete floor feeling".

Jeeze -- I am asking for the impossible I suspect.

Thanks in advance.....

No, you should not forget the pad that goes under floating floors. Real wood floating floors have less of that "tapping" sound than laminates. There are thicker, more sound absorbing materials available which would also be good insulaters for that "cold" slab (which is considered a subfloor, BTW). But it sounds like you don't want a floating floor and prefer a direct glue down. Glue downs are more difficult to do with many things to take into consideration. I've seen some pretty bad jobs by DIYers who thought they could handle it. And on the other hand, you maybe someone who can. It isn't rocket science (darned close though ) Lots of "tricks" that aren't mentioned in the instructions, like wedges and blue tape. Perhaps you could go to a jobsite and watch someone install a gluedown OR buy a video. Good luck!

The 4 most costly DIY mistakes...

They rarely undercut the doorjambs. It looks terrible with caulking gobbed in there.

They don't understand what 1/8 inch in 6 feet - 3/16 inch in 10 feet, is talking about, when subfloor specs mention it. They install right over it and blame hollow spots on the glue, releasing.

They don't understand or know how to properly test for subfloor moisture. They blame the wood and the "water proof" adhesive.

They buy it, bring it home, and start installing it an hour or two. Big, Big mistake. They blame the wood when it gaps all up, or it buckles off the floor.

I too am considering doing major hardwood over slab installation. Unlike cd, I am planning use of nail-down prefinished following instructions given on nofma.org site (6mil, ¾” cdx nailed down, 15# felt roofing, then flooring). Am leaning toward Mirage S&B nail-down. On-grade slab is 12 years old in Phoenix, with no apparent moisture problem and Bruce “Toast” glue down in 2 rooms for that period (which will be replaced). Will replace all baseboards and shave door bottoms if necessary, so I can accept 1-1/2” height increase. Am experienced wood/DIY’er with most of the tools on-hand already. Here are my questions:

1. Where can I find moisture testing procedure for slab?
2. Assuming no moisture problem, should I seal minor cracks in slab with something like plastic cement. Would like to avoid mastic mess if possible.
3. Is 6mil moisture barrier enough? What about the concrete nail punctures in this moisture shield?
4. Some recommend 5/8", wouldn't 3/4" ply be better?
5. Will ply make up for minor slab cracks and height differences or should I use thin-set if slab is not absolutely level?
6. Any advantage in doubling 15lb felt and 90 degree rollout?
7. Is Harbor Freight T&G nailer (http://www.harborfreight.com) by Central Pneumatic as high a quality as the Bostich version? It sure looks like the same nailer for a lot less $.
8. Can finish stapler be used where T&G nailer will not fit (under where shoe molding will go)?
9. Does everyone "rack"?
10. Has anyone installed Mirage flooring? Is it as good a product as some think? Any suggestions as to other manufacturers (natural oak 3-1/4")?
11. Any other tricks to doing over concrete installation?
12. I have 2500 sq ft to do and local installer wanted over $16,000 to do it excluding actual flooring and all baseboards. Add the flooring/baseboard cost and we were talking serious money. If that’s the going rate in Phoenix, you installers should come out here or I'm in the wrong business! Unless I win the loto, the only way I’ll see real wood in this house is to do it myself. While I am comfortable doing the work and expect the project to take at least a month, I wonder if I am biting off more that I can chew.

Comments please before I commit to ordering the flooring without professional installation included. All help appreciated and thanks in advance!

Hey VP, That's alot of questions! But since I'm in a generous mood, I'll do my best to answer.
1) Calcium cloride test is most reliable and prefered by most flooring manufacturers. Local floor supply (for pros) will have kit.
2). Use a urethane caulk, if you like. NOt really necessary unless crack is large (1/4" or more)
3) I have seen nailed only plywood subfloors over concrete fail many times. The method I prefer is instead of 6 mil poly, use a cheap grade of sheet vinyl and full spread glue to slab (After you flatten that slab!). Then glue 2x8 OR 4x4 panels of 3/4" CDX to vinyl using Franklin Advantage AND nail CDX with 1&1/2" fluted masonry nails. The vinyl and the Franklin glue will act as a vapor barrier. Don't rely on glue only.
4) 3/4" YES.... 5/8" NO
5) Try to level slab. 3/4" ply will ride over some flaws. Since you're installing a prefinished floor, subfloor should be as flat as possible. P.S. You can sand the CDX a little bit, not too much!
6) No, one layer of #15 is fine. Lay felt parallel to direction of flooring, overlap seams by 4"
7) It's what's inside that counts. Rent the Bostich!
Finish NAILER, no staples through the face. ALL fasteners can be NO longer than 1&1/2". Where you face nail, use 1&1/4"
9) No, they don't.
10) Mirage is tops!
12) $6.40 per sq.ft. is alot for labor only but what does that include? If it includes demo, vapor barrier, plywood subfloor, all installation sundries, flattening the slab, and installing your flooring, then it is probably about right! Plywood over concrete is alot of WORK! And alot of RISK!

2500 sq.ft. of DIY, plywood over concrete. You better plan on alot of weekends working or taking time off from your job!

Thanks Gary for the great advice and your informative comments to others elsewhere on this board! Took your advice and ordered the Bostitch stapler. Am also ordering my flooring this week and have settled on Mirage. Yes I do have a lot of free time. Good thing as I’m going to need it!

Have read elsewhere on this site that one can float a ¾” CDX subfloor over a 6 mil vapor barrier. From a moisture standpoint, that makes sense because the vapor barrier is not penetrated with tapcons or nails plus the workload/stink of glue and fasteners is eliminated. With this method I take it one would still allow expansion space between panels and at the edges. Does the flooring weight keep it all from shifting or what? Has anyone successfully used this method with ¾” nail down? What are the disadvantages of this? Am I correct that most professionals would not even consider this method? Gary, I assume that you still favor your glue and vinyl under CDX method but that sure sounds like a lot of work compared to simple poly. Would a whole surface glue down of 10 mil be nearly as good? After all, it is the glue that seals the concrete fasteners, right?

Has anyone used the Ramset TrakFast TF1100 gun? It looks like the largest 1-1/2” pins would work ok for fastening ¾” CDX to a concrete slab and it would be fast. Or how about a simple T nailer like the Bostitch?

Lastly, when laying the flooring would anyone use a T molding for a same underlayment and elevation direction change or would you simply butt the two directions together tightly and nail? Because of height requirements on all my mirrored closet doors that cannot be easily cut down, I’ll need to use reducer strips along the tracks. And my two steel-clad French doors are going the need a little trimming along the bottom too. Soooo many things the think about! Hey, this is my first floor ok.

This board is a great resource. Thanks to all!

Hi VP,
A reason for not using a floating subfloor was your desire not to have a Pergo-like feeling. I've walked on floated subfloors and they are similar to the effect of a floating floor. You are correct that a floating subfloor will be less work and material outlay but I prefer the two layer system of 1/2" CDX fastened together for a total of 1" thick subfloor (15/16" nominally) over 6 to 8 mil poly. With this system, one does not need to worry about panels shifting as much because when they are fastened together, they lock themselves together creating a monolithic subfloor. Not the case with a single layer 3/4" CDX subfloor. You may be able to forget the vapor barrier under your CDX if the slab tests within specs AND you glue the CDX down with a mc urethane adhesive. The vapor barriers are added protection against moisture problems and are usually recommended. I still prefer my system but each to there own. I think trying to glue down poly would be a messy nightmare but it is a suggested system by the NWFA and NOFMA. You could also glue down two layers of 15 lb. asphalt felt with an asphalt mastic. Again a messy system (I've done this but feel it is not as effective as a vinyl floor) Can't comment on the fastening tools you mentioned. I've only tried powder activated (didn't care for them) and hand nailing. I would think that the Areosmith or something similar would work fine but have no experience with them. The subfloor panels, whether you float or attach, should be gapped 1/8" minimun and allow 1/2" around perimeter. It's difficult to comment on your trim needs. Every job has different requirements and you kinda figure it out as you come across them. If possible, put the tracks or guides for your mirrored doors on top of your new floor. Trim sloping down to tracks looks crappy, IMO. I'd try to remove upper tracks and sheetrock above to gain additional clearance before accepting tracks sitting lower than the floor. Good luck

Ya Gary, gluing down poly would be a mess and the adhesive could disolve the poly.

If you going to glue a moisture barrier, 2 layers of 15# asphalt impregnated felt are recommended. Glue each layer and over lapping and gluing the seams.

I like using Henrys asphalt mastic, found in the roofing sectrion.

Anyone have experience with eflooringwholesale.com?

My plan (but I am open to suggestions):
1) Remove existing carpeting and baseboards
2) Level and clean concrete slab as much as possible
3) Spread 10 mil poly sheeting over entire floor, extending slightly up baseboard and gluing any seams with construction adhesive
4) Lay 2’ x 8’s of ½” CDX in same direction as final nail-down flooring boards, leaving recommended spacing between panels and walls
5) Lay second layer of 2’ x 8’ ½” CDX 90 degrees out from first layer with correct spacing
6) Fasten second layer to first with ¾” finish nails (have a 16ga air finish nailer on-hand)
7) Cover entire plywood sub-floor with 15# roofing felt
Install nail-down 3-1/4” prefinished T&G
9) Install 6” MDF baseboards and quarter round molding

You mention the “Pergo feel”. Yes, I would like to avoid this. With two opposing CDX layers, will that “feel” be minimized and/or be eliminated? Will this hybrid floated floor generally feel like the layers were glued?

Will there be a movement problem given that we are talking about a near solid 1-3/4” of wood over a smooth and level concrete slab?

With a floated floor, how does one ensure a tight fit around “no molding” areas like door jambs – without using caulk or fitting tight (and risking buckeling)?

Gary: would you still go with your glued-down vinyl and single layer of glued/nailed ¾” CDX?

While flooring is enroute, I have 3-4 weeks to decide. All comments appreciated!

Thanks!
VP

VP,
On item 3), one cannot use construction adhesive on polyethylene. Instead, overlap the poly by 6" and tape the seams together with the stickiest duct tape you can find.
On item 6), using finish nails to attach the plywood together won't work. Now is the time for your construction adhesive (or any quality adhesive for wood). Glue the panels together and use 5/8" or 3/4" screws to attach panels till glue dries. Be careful not to drive the screws too deep or you'll puncture your vapor barrier.
A floating subfloor will always have some degree of bounce to it and it will behave similar to a floating hardwood floor but because it has more mass, it should feel more substantial. As far as fitting around door jambs, sorry to say this but if you don't know about undercutting jams and casings, perhaps you need to go over the installation basics before you take on this project. I prefer the feel of an attached subfloor and I've seen many nailed only subfloors fail. That's why I always glue and nail my CDX down. But what to glue the CDX to has always been the issue. I've found cheap $4.00 a yard vinyl to be the answer. You can use 2 layers of 15 lb. asphalt felt but that ashalt mastic is slow drying and I'm not sure you could use a urethane adhesive over it. My system is designed for the slabs where there maybe moisture problems or where one needs to ensure there will not be a moisture problem in the future. You could substitute Taylor's "Lock Down" concrete sealer and their 2170 adhesive instead of the vinyl. That would probably work as well although I have not used it because it is new.

Gary - Before I start any project, I always try to learn everything I can about doing it before taking it on. Besides the flooring I’ve already ordered Don Bollinger’s “Laying Hardwood Floors” DVD. No doubt I will learn lots of techniques and other tips from this. Simply had not thought about the details much as I am concentrating on the big picture of which sub-floor method to use right now. I like the two layer floating method for it’s simplicity and lack of mess but the “pergo” effect has me concerned. The moisture resistance, security and permanence of your vinyl method also appeals to me but I do not like the idea of spreading two different layers of messy adhesive. Right now I am leaning toward the floating method. But that could change tomorrow. Either way, the cost of Mirage flooring is substantial and I would not want to ruin it with a sub-flooring that is not up to the task. Decisions, decisions but at least I have the pros and cons of each thanks to you and this board. Thanks again!

Have question about floating aspect of my plan. With plywood sub-floor, my plan is to leave ¾” spacing from all walls and ¼” both from jambs and between each plywood piece. Since this is a whole-house job, do I have to worry about the floating floor shifting much? Is there any problem with the narrower parts that pass through doorways and/or change directions? Am concerned about possible stress points. We have heavy furniture and once that is in place, I can’t see things moving much. But I do not want the change-of-direction places to pull apart or buckle. Yes, jambs and most cabinets will be undercut with Crain 820 jambsaw. Would there be any advantage to using thicker plywood for one or both layers throughout the job? Finally, do I need to cut kerfs in plywood that are mentioned elsewhere, if I am not gluing?

Working on layout now. Two of my favoite orientations are shown below but I am open to suggestions. Should I keep it all oriented the same way as much as possible? If anyone sees glaring gotchas or potential pitfalls with either of these, please let me know! All comments are much appreciated!

The old carpet tear out and sub-floor install begins right after the turkey is served! Thanks to all for the great advice and to everyone who contributes on this board!

Van

OPTION 1:


OPTION 2:


As reminder: Here’s my plan for ¾” over concrete slab - will first clean and flatten slab with thin set, if needed. It is pretty level already. Moisture throughout the on-grade slab is not a problem. Then will lay 10 mil poly (Home Depot had this discounted for the same as 6mil!) under two perpendicular spaced layers of 2’ x 8’ x ½” CDX, gluing and screwing top layer to bottom layer. Then one layer of 15# felt under 3-1/4” pre-finished planks fastened using 1-1/2” staples from Bostitch MIIIFS gun. Have a Crain 820 saw ready for the undercuts and mitre saw ready for the new 6" baseboards. Highly recommend eBay for tool buying. Saved me mucho dinero.

Oooh, my cheesy graph paper layout diagrams are put to shame...

Why not run it all the same direction?

They do suggest and highly recommend "T" moldings across doorways, to split the installation up, or as you have pointed out, it could get in a bind, and the doorjambs are usually the culprit with a flow through installation.

I have a similar question and rather then posting a new question I thought I'd add to this one. I've whipped up a very very rudimentry and rather inaccurate representation in mspaint, not even vaguely as nice as the above but hey, it gets the point across and I only had 2 minutes to do it .

This is a representation of the various rooms that I will be laying braz. cherry in (prefinished):


The brown dots represent areas that will be getting braz. cherry and the beige dots represent existing tile work that will be staying in place. The arrow shows the direction I am planning, thus far, to run the flooring. I noticed the suggestion about using t-molding at doorways, would that be appropriate in this case? I'm slightly uncertain how I will go about installing the wood throughout the rooms and maintain consistent and straight layout/lines while flowing into other rooms...?

thanks much and any comments/suggestions are vastly appreciated