Floors using the past to improve on the future.

With unprecedented activity in luxury residential development, flooring consultants and contractors have seen a surge in business over the past several years. Current design trends are a factor, especially regarding wide plank hardwood flooring.

Because of the high cost of materials and installation with these floors some developers opt to use pre-finished engineered wood plank flooring, in lieu of solid wood planks. There are some benefits in addition to savings, but there is a wide spectrum in the quality of these products that ranges from efficient to very bad. It is not surprising that the industry is experiencing unacceptable levels of failure, primarily due to the use of marginal quality materials.

Most flooring experts recommend solid wood planks over engineered wood flooring systems. In recent years, some of us have even returned to such time-honored installation methods as gymnasium-style floor systems. These "isolated" systems require perfectly level concrete slabs, so that floors will not deviate more than 1/8-inch in any 10-foot radius. A closed-cell sound attenuating blanket is rolled out and glued down directly on top of the level concrete slab. Two layers of 3/4-inch plywood laid at right angles, one over the other, are fastened together with adhesive and wood screws. The final layer comprises the solid hardwood floor planks, which are nailed into the floating sub floor assembly.

That is the sum-total of an effective and dependable resilient, sound attenuated flooring system. Of course, improvements have been made in the 50 or so years that this flooring system has been used. Many consultants and contractors have replaced the plywood sub floors with AdvanTech, a highly stabile product that is less susceptible to dimensional changes. It is also sustainable and free of formaldehyde content--another benefit.

The gymnasium-style system requires five layers to produce a resilient sound attenuated hardwood, wide plank floor, starting with the level concrete slab through the installation of the solid wood planks. But the result of this extra effort is a floor that will withstand the stresses of heavy use and seasonal changes. It's also a system that adds approximately two-and-three-eighth inches of height to the total thickness of the floor assembly from the concrete slab and should be part of the initial plans.

The most prevalent flooring failures in new buildings occur because of poorly manufactured pre-finished engineered wood plank flooring. With few exceptions these systems are built for beauty, but not necessarily long-term stability. From a developer's standpoint, though, they are beautiful and faster to install. A three-layer installation process begins with gluing a sound attenuating blanket directly into a concrete slab.

The engineered floors are generally comprised of a hardwood wearing layer bonded to a multi-layer hardwood plywood base. The floor is then glued to the sound attenuating blanket.

What makes this system so tenuous starts with the quality of the actual product. Too often the wearing layer is attached to incompatible backing, so it separates with minimal wear and tear. The same thing occurs when the top layer is uneven or too thin for the backing. In addition, the wearing surface can easily disengage from the plywood base as a result of atmospheric changes, and cause buckling cupping. Excessive shrinkage in winter may result in separation, cracking or de-lamination. The moisture content in wood is normally between 6.5 and 8%, but winter heating systems often dry out the wood and cause temporary shrinkage. Finally, if the concrete slab is not completely level before the sound attenuating blanket is glued down, the bond of adhesive will break and de-lamination will occur.

It would be great to see trends in flooring design shift back to narrower solid wood planks. Whether straight, herringbone or parquet, narrower planks are inherently more stable. Nevertheless, the wide plank floors we consulted on at 15 Central Park West and the residential condominiums at Bloomberg Towers used gymnasium-style systems. Our clients can count on these superb floors remaining intact for the life of the buildings.

Moving forward, we hope these types of quality systems will set the standards for flooring in all new developments.

JANOS P. SPITZER, PRESIDENT,

FLOORING CONSULTANTS