The flooring that was put down was not simple 2x4's. It was a product manufactured by Birger Juell, Ltd. in Chicago. It is made from very old timbers that have been salvaged from deomolition sights. The wood is extremely dense and all of the edges are rounded to provide a tile like appearence. It is then colored and treated to protect it.

The product is then applied to the floor with a special mastic and grout that is only available from Birger Juell.

If you are committed to using this method I would think you might try some other type of wood other than the typical hemlock or fir that is used in construction. Then you have to take into consideration securing it to the surface and sealing it.

Let us know how you make out.

Steve