Hello everyone! I have been reading the message board and also talking with some installers - finally I have come up with a plan for my hardwood floor.


Situation: I live in San Diego (100deg summers, mild winters) and my house has a slab on grade foundation. I have noticed some efflorescence on the slab in the garage and also in a room where I had to pull up the carpet (previous owner had pet problems.) Concrete seems dry and also very brittle - when I took out the old carpet tack strips, popping out the nails left 1-4" wide "craters" in the surface (concrete about 30 years old.) I want to replace the existing carpeting with a hardwood floor and I would really like to do the project myself so save money.

Option 1: Plywood+Engineered. I started out wanting to put in a 3/4" plywood subfloor attached to the concrete and laying 3/4" solid wood over that, simply because my last house had solid flooring and it looked great. That was also a home with a raised foundation and a wooden subfloor, so perhaps it is not fair to compare the two. Anyway, this approach now seems like a ton of work in light of how brittle my concrete seems to be - I don't think that nailing with a .22 powder gun would really hold the plywood down, and I know from past experience that using only Tapcon screws would be a lot of work. I know now that I could also use engineered wood, but even then the hardest part would be the plywood subfloor. Height would be 3/4" + 3/4" = 1.5", and I would have to trim my doors at the bottom.

Option 2: Glue Down Engineered. A local installer almost talked me into gluing engineered wood directly to the concrete after covering it with MVP or a similar moisture barrier. However, I know that my floors have old paint on them in addition to the efflorescence and there's no way I can truly clean them without sanding - the pro said his crew always sands floors like this with a big vacuum sander. In addition, the MVP and glue would cost an arm an a leg! Also, the final height of the flooring would probably only be about 1/2" thick, leaving rather large gaps under all my existing doors (our carpet and padding would probably be just under 1.5" thick.) I think if I were to go this route I would let the pro do it for me.

Option 3: Dricore + Engineered. I just found out about DriCore and SubFlor Advance/Supreme products. While these are expensive, at ~$2 per square foot I don't think they would really be any more than the sealer+glue used in option 2. It might be more than the plywood in option 1 (but I would still have to use a moisture barrier even in that case.) With this system I would avoid having to install a dedicated moisture barrier and installation would be about as easy as it gets. I would then nail engineered wood on top of the Dricore. Height would about 7/8" + 3/8" = 1.25", a close match to my existing carpet. This is my favorite option so far.

Option 4: I know there are more options, such as floating floors, but I like the feel of a nailed/glued floor the best.

- Has anyone used Dricore or Subflor inside their house?
- Does it sound hollow to walk on once the finished floor is in place?
- The installation instructions at dricore.com say it is enough to just put down a layer of building paper over the subfloor and then nail down the engineered wood. Is that really all there is to this?

Thanks,

- Ari

It is all going to be your choice and what your budget will allow.

Personally, I like the direct gluedown, idea the best.

I was thinking about the approach, but I didn't see a great advantage to those systems unless one has a severe water problem. They are supposedly designed to allow occassional water to even drain under the little "feet" and over to a sump or floor drain. That doesn't seem to be your problem. I will say, I talked to a Lumberliquidator guy from Plano texas, down where all the houses are slab on grade construction, and they like it a lot. They have their showroom on it no less.

I am currently trending towards a single layer floated subfloor, using 3/4" ACX cut into 18" wide strips and laid either at 45 to the floor, or staggered 90 deg to floor.

But I will be stapling 3/4" quartersawn oak, 2 1/4 width, over the above. The quartered oak has a lot of 4 and 5 foot pieces, which are quite strong and dimentionally stable, which means that the oak itself will be pretty stable and the subfloor will be serving mostly to just hold the oak together during the install. Or so I imagine it.

I am no pro, and this is my first install over concrete. So take my advice with that caveat!

CD:

Last year I put down almost 3000 sq ft of 3/4 inch Mirage Beech Classic nail down prefinsihed over a concrete slab. Floated it over 15# felt, 2 - layers of 1/2" plywood screwed and glued together and 1 layer of 10mil poly. All baseboards were replaced with white 3 part 7" Victorian style and jambs were undercut. I posted extensively on this board with pictures but don't know if those posts are still available. Results were fabulous. The floor is soft but very comfortable to walk on. Warm in the winter and cool in the summer (Phoenix) and far superior to the glued down Bruce that was originally put down in the entry and kitchen area (very hard and cold). The project was a massive one and probably the hardest part was flattening the concrete. I used thin set since I was not gluing to the slab. Maybe the administrator can find those old posts as there is a lot of info in them. Best of luck with your project. Although I did what I think is a very professional appearing job, I did learn that I have no desire to go into the business. But I certainly admire those who do it for a living.

VP

That’s pretty normal. If that is what is causing the concern that your floor is brittle then I don’t think you really have a concern. Powder actuated nails will hold the floor. I would take a small piece of plywood shoot it into the floor with a .27 cal PAN gun putting a nail about every sq ft. If you can’t pull it up with your hands then it is not going anywhere. It’s the cheapest route with the price of glue.