Frank VandePutte - Wood Floors & Stairs 

Inexpensive wide board wood floors are often engineered flooring with a thin peeled or sliced veneer.  These inexpensive  engineered wood floors have a 2-3 mm hardwood surface. A moment I absolutely dread when doing wood floor sanding and refinishing estimates is telling a homeowner that their wood floor can’t be sanded and refinished. Often a flooring salesperson has told someone that an engineered floor can be sanded once or twice. In a perfect world that might be true. But for a variety of reasons, engineered wood floors with thin (3 mm or less) veneers often cannot be sanded without sanding through the veneer. If you are buying a wood floor, check to see if the wood is a ¾” solid wood or a high quality engineered floor with a dry sawn veneer of 4 or 5 mm. If it isn’t, don’t assume that it can be sanded and finished.

Because wood is hydrophilic (loves water and will readily absorb it,) wood expands in the presence of increased humidity, and shrinks as the air around it dries. If you choose 4" or wider, solid wood flooring, you need to maintain a consistant, healthy relative humidity in your home, or the expansion or contraction will be very noticable. For flooring 4" and wider, consider a high quality engineered wood floor. Solid wood products should NEVER be installed below grade (below ground level.)  Unless there are reasons why a solid floor should not be installed (i.e. below grade, being glued to concrete, or radiant heat in the floor) you cannot beat the value of a 2 1/4" by 3/4" or 3 1/4" by 3/4" thick solid wood floor; it is least likely to show cupping or gaps.

The best quality engineered wood floors have thicker dry sawn veneers, not thin rotary peeled or sliced veneers.  At the surface, they look like solid wood floors whereas the rotary peeled veneers look like plywood. 

Below is a product that has a sawn veneer.  It has almost as much of a sandable surface as a 3/4" solid wood product, and comes prefinished or unfinished, so you can have a high quality custom floor. 

Buying a wood floor? Beware of thin veneer engineered flooring, and wide board solid flooring.

Engineered wood flooring has greater dimentional stability; meaning it will expand or contract less than solid wood when the relative humidity changes.