Hardwood to concrete floor, with nothing in between?? - Contractor Talk - Professional Construction and Remodeling Forum

SBI · 07-22-2008, 02:21 PM

Don't know how it is done anywhere else, but the area of North Carolina I am in (Eastern) has just in the past few years really started to build more concrete slab houses. For the most part, they have all been on crawl space foundations. I have built a couple now but the biggest issue we've seen is the concrete being un-level and in my 1st case, the epoxy used to glue down the hardwood flooring, being too thick in some areas and not fully hardening. This causing a squishing type of feeling in the hardwood (certain pieces of the boards to move up and down slightly due to the low spots).

My question is: What are the best methods out there to level a concrete floor??

I've seen another post where you would level the floor with Ardex, seal it, vapor barrier, 1x's at about 12" o.c. then nail the hardwood to it. But in the interest of money, especially in the tough bidding wars we have now and projects alread underway, is there anyway good way to level that concrete floor so the hardwood can continue to be glued down to the floor??

Using Engineered by the way. I know others that have in the past used a vapor barrier, then 3/4 ply, then the hardwood. For both that method and the 1x's at 12" o.c., are you guys glueing that down or nailing it to the concrete???

Thanks.

paccstfloors · 07-23-2008, 12:01 PM

Make sure your slab is dry and level.
It should be flat to withing 3/16 in 10'.
Ardex is probably the best product to float out lows spots. Just make sure you use the primer that goes with it.
Grind down all high spots with a 7 1/4 grinder attached to a vac.
Blastrac makes a good grinding system.
Once you have made sure your slab is flat and clean, use Bostiks Best urethane adhesive and use thier reccomended trowel for your flooring choice.
If you have a higher moisture content that the manufacture of the flooring allows, use Bostiks MVP as a moisture barrier. Its applied using a trowel and when used with Bostiks Best, is as good a moisture barrier there is.

Floordude · 07-23-2008, 12:13 PM

Quote:

Originally Posted by paccstfloors

Make sure your slab is dry and level.
It should be flat to withing 3/16 in 10'.
Ardex is probably the best product to float out lows spots. Just make sure you use the primer that goes with it.
Grind down all high spots with a 7 1/4 grinder attached to a vac.
Blastrac makes a good grinding system.
Once you have made sure your slab is flat and clean, use Bostiks Best urethane adhesive and use thier reccomended trowel for your flooring choice.
If you have a higher moisture content that the manufacture of the flooring allows, use Bostiks MVP as a moisture barrier. Its applied using a trowel and when used with Bostiks Best, is as good a moisture barrier there is.

Bostik's Best is not as installer friendly as Bostik's BST ot TKO. You better have the concrete as flat as 1/8 in 10 feet, if you want to use Bostik's Best. It slumps out and does not hold its trowel ridges. If it were me, I'd go the Mapei route and use there WFM(which is better then Bostik's MVP) and Mapei 990 urethane adhesive.

paccstfloors · 07-23-2008, 12:43 PM

I have never used the Mapie system so I couldnt say.
I do know Ive never had a problem with the MVP system.

gideond · 07-23-2008, 07:04 PM

Level it with a good self leveler like the Ardex products mentioned. Then I'd personally recommend an engineered product like Kahrs which floats over it's own pad, which includes a vapor barrier. It's real hardwood on top and installs very much like laminate. It eliminates a lot of the problems inherent to hardwood on a slab. And installing it is a lot faster and easier than gluing.

pfloyd · 07-23-2008, 08:31 PM

I just did a bit of that using DriCore panels in a garage. First time, it worked well. Only drawback is its an inch thick, it will bring the floor up that much.

Theyre sqare OSB panels with corrugated plastic underneath to allow an air space and keep things dry. Your slab has to be close to level, you can only shim these things up to an inch.

orson · 07-23-2008, 08:48 PM

JLC just had an article about gued down hardwood on slab in their last issue, I think it was on the cover but I can't find it....wife must have hid it

HLF&Flooring · 08-01-2008, 01:21 PM

Level it with Ardex then check into VersaShield Flooring Underlayment. It's fiberglass based vapor barrior that is ridgid and floats over the concrete and completely okay to glue to.