I was told that solid wood floors could not be glued to a concrete slab only nailed down to plywood that has been installed over the slab. I have found that all 3/4 inch solid strips require nailing down but some cheaper thinner solid strips allow you to glue them directly to the slab. Why is the thinner solid wood allowed to be glued when the higher quality, thicker wood can not. this seems backwards to me. Also if you where going to use a thinner wood wouldn't it be better to use engineered instead of a solid strip because of the different layer all in different directions. Also if this is not the case what are the advantages of the thin solid strip over engineered. When people do recomend the solid strip it is almost always because they don't like the word engineered and seem to be confusing it with Laminate. It seems to me that after installation you can't tell the difference between engineered wood and solid wood just by looking at it. any help would be appreciated.

Let's see if I can answer some of your questions. At one time, all wood floors were nailed down, even parquets. When slab construction came on the scene, different methods were employed to attempt to install wood on the concrete. 3/4" parquets were glued directly to the concrete and I imagine some attempted to glue strip floors down as well. But because wood floors expand and contract width wise, and because moisture barriers were not available, most of those floors had cupping and buckling problems. The thicker the wood (3/4") the more it will absorb moisture and therefore is less stable than a thin solid like Natural Reflections (one of the few solid strip floors that they claim can be glued directly). Engineered (multi-layered cross ply construction) floors were designed specifically and originally to glue directly to slabs. So, yes, an engineered will perform better in terms of stability than a solid, on either a wood subfloor or a slab. However, many engineered floors are made from peeled veneers which do not look the same as a solid wood. The better ones are made with either a solid sawn face or a sliced veneer and look much more like solid wood flooring. Now, keep in mind, all wood floors are solid wood, just some are cross ply engineered for stabilty. They do look different than regular, non engineered floors to the trained eye. Also, it costs more to manufacter engineered than thin solid strip. That is why Natural Reflections is usually less money than a quality engineered floor. So the reasons behind thin solid floors like Natural Reflections is appearence, cost, can be glued to concrete and low prifile (clearence). The disadvantage is can only be refinished (sanded) about one time due to the amount of wood before one gets to the T&G. There's not much of it. For the price, appearence and ease of install, I think it is a good value. It still will not be as stable as an engineered wood floor and may experience cupping due to moisture in the concrete.

thanks