Hi, I am about to install solid prefinished 3/4" x 2 1/4" asian Rosewood on a slightly above grade 50 year old slab. It presently has a solid parque floor adherred to it already which looks like it is in very good condition. Glue still holding, no cupping etc... My question is: do you consider it risky to install the solid floor over the floating floor system Dri-core with its built in vapor barrier, or better to install over fastened 3/4" underlayment with a 6 mil poly under that and a 15 lbs. felt between underlayment and solid floor ? or use an engineered floor ? Am I nuts ? Thanks, JSL

You cannot float a floor over parquet on concrete. The parquet will buckle! Seriously!!

If you lay plastic down and then fasten the plywood subfloor, puncturing the plastic, what have you accomplished? It is no longer a moisture barrier!!! It is called a waste of money.

Float the plywood subfloor over the plastic, after you remove the parquet. You will need to cut the plywood into 2' x 8' panels and stagger the joints, running them the opposite direction of the finish wood layout.


I personally won't do a ¾" over concrete. It can be done, but too risky. I have never lost money on a job I didn't do.

There are ways to successfully install a 3/4" solid wood floor over a concrete slab. In your case, you must remove the existing parquet wood flooring as if you do not, it eventually will rot due to trapped moisture. Once you remove the parquet flooring, you will need to thoroughly clean the slab by scraping or sanding off all old adhesive. Two methods work well. You can install pressure treated 2x4 sleepers (screeds) or 3/4" plywood as a nailing base. With sleepers, I cut them to 48" lengths and stagger (off set) them 12 O.C. and install by gluing and nailing. Once that is done, drape a 8 mil polyethylene plastic vapor barrier over the sleepers, making sure to overlap seams by 12 " and seal seams with duct tape. Better yet (I have have never had this system fail) is to install a inexpensive sheet vinyl floor over the entire slab. It must be a full spread glued down vinyl floor. Then seal the seams with the appropriate seam sealer. After that is done, cut 3/4" CDX plywood into 4x4 panels and install over the vinyl floor using a urethane wood floor adhesive and 1&1/ 2" concrete nails. I like Franklin Advantage as it has a special binder for vinyl vapor barriers. Off set the seams of the plywood and space them 1/4" apart. The nailing is important. I use a 2lb. sledge hammer and it works great. You can use powder activated nailers but nothing beats hand nailing. Nail in a 12" grid pattern. Once that is done, lay your 15lb. asphalt felt and your ready to go. Unless your slab is below grade and wet (moisture testing should be done), this is a system that while expensive, has never failed me. Good luck!

Good advice given in the above posts. If you reside in a wet area, cut-back is required under the plastic to seal the concrete surface.