Floating a 3/4" Solid Hardwood Floor Over Above Grade Concrete?

Posted by on December 19, 2006, 3:06 pm

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
contrete.

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?

-Marc

Posted by dpb on December 19, 2006, 3:57 pm

lefebvre@iwavesolutions.com wrote:

> 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. ...

...

> What are your thoughts, ideas, recomendations, ...

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.

https://www.nofma.org/Portals/0/Publications/NOFMA%20Installing%20Hardwood%20Floors.pdf

Posted by resrfglc on December 19, 2006, 4:25 pm

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.

>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
> contrete.
> 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?
> -Marc
>

Posted by Swingman on December 19, 2006, 4:52 pm

> I am interested in floating a solid hardwood plank floor (3/4" x 3").
> Has anyone successfully done this?

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
all walls.

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
crawlspace foundation.

--
www.e-woodshop.net
Last update: 12/19/06

Posted by on December 19, 2006, 10:27 pm

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?

Swingman wrote:

> > I am interested in floating a solid hardwood plank floor (3/4" x 3").
> > Has anyone successfully done this?

> 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
> all walls.
> 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
> crawlspace foundation.
>
> --
> www.e-woodshop.net
> Last update: 12/19/06

Page 1 of 4 1 2 3 > last >>

Similar Threads	Posted
Insulate under floating floor below grade?	December 11, 2006, 4:14 pm
3/4 solid hardwood over gyp-crete?	November 18, 2006, 3:41 am
Floating floor???	May 27, 2008, 9:55 am
Buckling hardwood floor	October 11, 2006, 6:43 pm
Hardwood Floor Help Needed	May 1, 2007, 1:19 pm
Hardwood floor at stairs	September 18, 2007, 8:20 am
Lyptus hardwood floor installation	September 24, 2006, 3:32 pm
nails vs staples, 3/4 hardwood floor	April 29, 2007, 10:55 pm
Hardwood floor install: nail heads visible, what now?	July 22, 2007, 10:34 pm
Hardwood floor for dummy question, Any comments appreciated.	October 30, 2007, 6:45 pm