I am interested in floating a solid hardwood plank floor (3/4" x 3").
Has anyone successfully done this? I am leary of glue down application
onto the above grade cement slab. Here in Hawaii we have alot of
moister in the air and I feel that allowing the the floor to shrink and
grow and generally allowed to roam is a better option than locking it
down which then could lead to buckling and other nasty things. Plus
wood floors are supposed to give and take underfoot and not fee like
I have successful tried this in a small room in the house for testing
and all went well and it has been over a year with no issues to date. I
left 1/2" gap all round the room for expansion space. Now, I want to do
the main living room which is a lager space and higher traffic area.
What are your thoughts, ideas, recomendations, and concerns?
Go straight to the horse's mouth, so to speak (National Organization of
Floor Manufacturers) installation guidelines/instructions has all you
need to know...
You can install wood flooring above or on grade concrete if slab is
prepared and drains properly and proper moisture-barrier
protection/provisions are followed.
INSTALLATIONS OVER A CONCRETE SLAB. Hardwood flooring can be installed
successfully over a slab which is on-grade or above grade. Below-grade
installations are not recommended. The slab must be constructed properly
(dry and flat with a trowel finish). Watch out for water. New concrete is
heavy with moisture, an inherent enemy of wood. Proper on-grade slab
construction requires a vapor retarder such as 6 mil polyethylene film
between the gravel fill and the slab. While this prevents moisture entry
through the slab, this membrane also retards curing of the slab. So test for
dryness, even if the slab has been in place over two years. Slabs younger
than 60-days are generally too wet for flooring installation.
Absolutely ... around here (Gulf Coast) hardwood floors are routinely
installed on concrete slab foundations thusly:
The concrete floor is first sealed with a layer of hot tar.
1" - 1 1/2" "screeds" (ripped SYP 2 x 4's are commonly used) are then placed
on top of the tar about 12", or less, apart.
The hardwood floor planks are then laid perpendicular to the screeds and
nailed to them, leaving approximately 1/2" - 3/4" room for expansion along
The expansion gap is then covered partially by the baseboard and completely
by the shoe molding.
Hardwood floors done in this manner on concrete slabs generally survive
better in this climate than hardwood floors laid on the subfloor of a
Thanks for the tips. It seems that many installation provisions
recomended boil down to a nail down type installation, either over a
plywood subfloor over concrete, or the use of screeds. However, what
about my orignal idea of actually "floating" it?
Here is what I did on my test room:
1) My house is over 5 years old and the concrete is dry as its ever
gonna be. It tested well.
2) I laid out a poly/foam vapor barrier over the entire space, with 12"
overlaps and is taped using 3m blue tape.
3) I glued each plank of the 3/4" solid wood flooring to its neighbor
via the tung and groove.
4) left a 1/2" space around the entire perimeter of the room.
Thats it. The floor is floating much like an engineered product would
be installed, but is a solid 3/4" plank floor (3" wide). The room has
been going good for over a year now. Has seen all the seasons.
Is this a crazy idea?
"using 3m blue tape"
Hey, you have demonstrated that it works in your location. What can we
possibly add absent such personal experience.
Assume new installation is also at or above grade as well (below grade
installs over concrete are the iffy installations).
Not sure 3M Blue Masking tape would be my choice for the vapor barrier as
opposed to the tape sold for use with Tyvex House Wrap or similar.
I'm wrestling with a below-grade concrete basement floor I want to serve as
my workshop and would love it if your approach mightwork. But the moisture
would create MOLD big time if the wood pulled off the one basement wall is
From what I've found, there's little one can do with a below-grade cement
basement floor and medical advice is "don't spend time standing on
Well, he's demonstrated it for _one_ year for a flooring product that
traditionally installed could be expected to last multiple lifetimes.
Not exactly a conclusive test. :)
Hardwood flooring is definitely not an option for below grade. Unless
the slab was laid w/ an effective moisture barrier underneath and
otherwise prepared, it may be difficult to do much in a solid flooring.
Possible alternative would be the perforated cushioned pads for a
walking surface. I use livestock padding as it's significantly cheaper
than most sold as comfort pads.
"I use livestock padding "
I was pricing that at Tractor Supply and bought some of those 24" square
foam interlocking sections at Big Lots (6 for $12) to serve immediately.
But the concern I have is that they may hold the moisture beneath and create
a layer of mold between concrete and "livestock pads" which appear
Do you ever check beneath them to see if anything's growing there?
I use a 24"x24"x 3/4" foam padding product I got from an auto supply
store. It does trap moisture underneath (house built in 1945) so I stand
the pads, one each in front of lathe and TS, up on edge when I am
vacuuming and leave them up until time to use them again.
Works for me. YMMV
In a lab with concrete floors (and no moisture barrier beneath), I used the
heavy black "welcome mats" with rubber fingers in front of each major work
area. I turned the mats upside down so there was some air circulation under
the mat, and I had a solid surface to stand on. Worked quite well.
But, I don't have them in a basement, so if it's particularly damp I
suppose it _could_ be a problem. But, in the shop I only place them in
the places where I normally stand frequently, like in front of the
tablesaw, bench, etc., etc. Consequently, they're easy enough to flip
over and move if want one somewhere else temporarily. The particular
ones I was thinking of aren't solid, either, so that the amount of
moisture entrapped wouldn't be that much (again, unless it were
_really_ damp). They have about a 50% or more open spacing. Does mean
they collect the sawdust in the holes, but as they're not that heavy,
as noted above, all it takes is flipping one over to sweep. Most of
the time the shop vac w/ the floor sweep tool is enough, anyway,
OBTW, they were even cheaper than the solid ones by almost the 50%
factor so I gather they're basically priced on the amount of material
since they're mostly an artificial rubber, they're pretty much tied to
petro prices. I also have a thin, salvaged truck bed liner that I
didn't want in the truck that came w/ the used truck I bought that I've
tossed on the floor in front of the chopsaw bench -- it isn't nearly as
comfortable as the others, but even it helps noticeably both for softer
standing and not so cold in winter.
For most builders (at least in this area), perhaps. Mainly because it is a
departure from a method that _has_ stood the test of time, and one with well
known and relatively easy/cost effective solutions to problems that may
arise in the future for both the builder and homeowner.
For you, that does not mean that it won't work, but that only time will
Why not consider a floating floor product i.e. engineered wood floor? The
finishes available are durable (probably more durable than finish in place
floors) and the seams can be tight and near invisible. And it goes in very
fast. Use a good quality underlay.
That's _ONE_ year for a flooring material that can last 200 or more --
not a very long time yet.
What I see as potential issues --
1. The tongue and groove of strip flooring aren't made to fit to a
close tolerance for a glue joint. You don't mention what you used as
the glue, but I would be quite surprised if you can find a way that
these joints will last for a long period of time w/o eventually failing
at the joint. Remember, this is potentially a multiple-lifetime
flooring material and you've seen the results of your experiment for
only _one_ year so far.
2. For a large floor, you don't have any way to prevent movement
between boards over time other than the above glue joint -- rarely (as
in never) have I seen strip flooring which didn't need at least some
persuasion when initially being laid to close the joints and for a
large area I think you'll run into problems of a very high
rejection/wastage rate if you require every piece to be absolutely true
its entire length in order to pull joints tight during the
installation. The supplier will not think these pieces out of spec as
they would work fine w/ recommended installation techniques so this
will raise cost.
3. You don't say, but I'm assuming you didn't finish four sides (top,
bottom, two ends -- sides obviously can't be if gluing). Thus, as w/ a
convential strip floor, you still have three of the four sides
available for moisture movement. Over one year, maybe you got by, over
a long-haul I don't expect you to be so lucky. Finishing the
bottom/ends might help a little, but finishes don't stop moisture,
transfer, they slow it down.
Overall, I think you're risking a pretty sizable investment on an
unproven method of installation when proven methods are available. If
it were something that would be relatively easy to fix later, I'd say
"sure, give it a shot", but once this is down in an entire house, _if_
it does fail, you've got a real mess on your hands plus quite an
expense. I'm w/ the other poster who suggested if you want a floating
floor, buy a product designed to be installed that way.
It's your house and your money, but I'm not that kind of a risk-taker.
IMO, YMMV, $0.02, etc., etc., etc., ... :)
If high and/or stable humidity is a year round thing in Hawaii floating
shouldn't be needed as things would tend to stay constant (wet) and thus
stay put. Letting the flooring acclimate in the house and then installing it
would suffice. It's the seasonal variations and/or not letting the flooring
acclimate that tend to cause problems.
What about termites though?
DRIcore subflooring would be an option. Termites may not like this stuff at
all due to all of the adhesives and plastics. It might be worth checking
that out. http://www.dricore.com/en/eindex.htm
Another option, again with the termites in mind, would be PT sleepers to
flatten and PT ply subfloor, vapor/squeak barrier and then nail down your
wood finish floor. If the concrete is relatively flat PT plywood glued down
may work just fine however you may need two layers to deal with the
I'd be concerned with the termites if untreated wood were basically in
contact with concrete. They'd likely find it sooner or later.
On 19 Dec 2006 19:27:51 -0800, email@example.com wrote:
Follow the manufacturer's instruction. If not, a warranty is
immediately voided. You pay premium in HI for products now.
Adhesives, as I understand now have moisture barrier quialities.
Prepare the floor, get a good adhesive and put the floor down.
Floating in your test room may not have the same end result in the new
"Well, it doesn't happen all the time, but when it happens, it happens
It's Marc from recdotwindsurfing (and the old King of The Cape days. I
miss going to the Brazilian Grill in Hyannis). How are you and
Iyesha? I've seen some of your windsurf posts on recdot recently.
Sorry I don't have any advice for your floor question. But now if you
want to know how much downhaul to put on your sail, well maybe.
Take care and Merry Christmas/Happy New Year.
T.O.M. (The Other Marc)
instaled over concrete. While I can't remember the specifics of the issues,
the reader's digest version is that it, the flooring and the plywood
subfloor, rotted out in a relatively short period of time. Mike went
through the trouble of making sure there were no other water leaks that
could have caused the problem. He even drilled into the concrete slab that
was poured 25 years ago only to discover that it was the proper thickness,
the styrofoam under the slab was fine and the dirt below that was dry. I
think he concluded that the moisture in the concrete was causing the
flooring/subfloor to rot. He ended up putting down a slate tile with an
electric heating pad underneath.
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