I am installing 3/4" handscraped oak in my 2nd floor condo. Well, I was until I pulled up the carpet completely to find what I originally thought was plywood that had been oversprayed with primer, but some form of concrete substance. I say some "form of" because the room is approximately 320sq. ft. & there is not a single seam in the entire room leading me to rule out sheets of concrete backerboard. It looks like whatever it is, was poured. I assume there is plywood underneath this product, but don't know for sure. I'm a little hesitant to start hammering into the stuff because it already has hairline cracks in several places. Regardless, has anyone out there seen this product in condo/townhome developments, more importantly know exactly what it is, and how do you lay hardwood floors on top of this type of surface. The flooring contractor won't touch it because: a) he does not know the depth of the product when it comes to driving nails through it b) claims that the long term stability with expansion & contraction is a major issue due to cracking, degradation, etc.. There's another 160 sq. ft. of flooring to be laid in addition to the 320 with the same issue. Any recommendations would be greatly appreciated on how to turn this into a proper subfloor and proper installation. Until then, the floors are getting well adjusted to their new environment.
Thanks,
Trey

Return the flooring you bought and purchase flooring that can be floated. I think you have a light weight concrete over either a plywood or steel deck. You cannot/should not remove it. It's there for fire and sound. You cannot nail to it or glue to it. A floating floor is your only option, IMO.

That was definitely not the answer I was looking for, but I definitely appreciate it regardless. I take it you have seen this before. I was hoping that some sort of subflooring could be glued to it or nailed to it and then the hardwoods installed on top of the subfloor. Well, I'll give the store a call & see what they say....

You could float a plywood subfloor over it then nail your flooring to that but it will raise everything up quite a bit which may cause transition problems with other doorways and flooring. The minimum plywood subfloor thickness is 3/4" for a 3/4" nailed down floor so you would have 1&1/2" above the existing subfloor. Floating a floor over that lightweight concrete is your best bet. Many nice products to choose from.
http://www.hardwoodinstaller.com/hardwo ... loater.htm

Gary,
I likle the look & price of some of the floating floors I've seen. The reason I bought the 3/4" hardwood was because of the # of sandings / screenings that could be done. I have two dogs & over time the floor will go from looking aged & worn with character to completely losing their luster & a little destroyed looking. I was a little concerned with how many screenings / refinishes I could get out of engineered floors.

if I could make the transitions pieces work due to the 1 1/2" minimum rise, would there be any structural issues due to the amount of additional weight from adding the 3/4" subfloor then my hardwood flooring?

No, the weight of the plywood and flooring is not significant. A bookcase loaded with books will load the subfloor way more than any floor covering.



To be honest, most people only refinish their floors once or twice; and at ten to twenty year intervals. If you select a floor with 1/8" wear surface, you could get at least one refinish and perhaps two out of it. Recoating does not wear the surface down; only resanding does. Keep the floors up and you may never need to refinish. I like the look of solid myself. But it needs a good wood subfloor to install it over.

Gary I really appreciate all the input. I don't know if I can make the transition pieces work, but I'm going to measure just to see if it's an option. At this point I'd love to just do a floating floor; I'm trying to work an even trade with the retailer on some engineered floors. We'll see how this all plays out. I may even consider trying to install all the flooring myself I've gotten into this so deep at this point with the added cost of addtional subflooring, installation of subflooring, return shipping costs, restocking fees, etc..

Gary, I'm going to have to make the necessary changes to the doors & entry ways to the rooms because of costs involved if I return the flooring. Are there any documents on this site or any that you can recommend in general that outline how to "successfully" install a floating subfloor. Also, is there any problem with using 3/4" OSB as opposed to 3/4" plywood. I mentioned the "successful" install of the floating subfloor because it seems like no one on this site would recommend a floating subfloor as opposed to one that is nailed down. Also, what are the issues with a floating subfloor? floor instability, noise,etc.?

Not true. Perry and others on this site have recommended floating subfloors in certain circumstances. Fine Homebuilding had an article years ago featuring a floating subfloor. The NWFA may also have an article on it. It isn't new. The idea is to use two opposing layers of plywood, preferably 1/2", screwed together. You can glue them together as well as screw or staple. We had a poster last year who did this with sucess. It's not easy but he was quite happy with the results. If done correctly, it works well. However, it is material and labor intensive and when most folks inquire about it to us, who are paid professionals, they rarely ask us to do it because of the cost. It is less money to simply float a hardwood floor over the slab and that is what we would recommend. But because you already bought a 3/4" solid floor (which I would have not recommended in your situation), you are choosing to have this installed. A 3/4" solid floor needs to be nailed down (unless it's a Junckers floor) and that requires a suitable nailing base. Two layers of 1/2" CDX floated over your lightweight concrete will meet the requirement for an appropriate nailing base. I recommend floating it because the lightweight concrete will crack if you attempt to drive fasteners into it and glue will not bond adequately. So your only alternative is to install a floating subfloor OR install a floor that can be floated.