Wood Species Hardness and Stability
By: Jeff Johnson Mar 01, 2018 Category: Wood Species

Although over 90% of wood flooring that Jeffco sells is red or white oak, many other options are available for your flooring. American walnut has become a popular option because of its warm rich brown tone and beautiful patina with age. But how does the specie desired affect the long-term performance and appearance of your new floor? All wood floors scratch and dent (compress). The finish on your floor is just as hard as the wood under it. Do not think for a second that more finish will make your wood floor harder. It just doesn’t work that way. Most polyurethane finish systems perform best with only one to three coats applied to unfinished flooring. If you desire a floor that does not scratch, then consider luxury vinyl plank (LVP), a composite material with an image of wood on top. The domestic hardwoods in order of hardness, from softest to hardest are as follows: AMERICAN CHERRY, AMERICAN BLACK WALNUT, RED OAK, BEECH, ASH, WHITE OAK, MAPLE, and HICKORY.

Exotic species are generally much harder than domestics, are more costly, and offer fewer color options. Most exotic species are dark. From softest to hardest are as follows: AFRICAN MAHOGANY, TEAK, AUSTRALIAN CYPRESS, SAPELE, ROSEWOOD, TIGERWOOD, SANTOS MAHOGANY, BRAZILIAN CHERRY (twice as hard as domestic oak), AND BRAZILIAN WALNUT (IPE).

Other common wood flooring species include BAMBOO, RECLAIMED ANTIQUE HEART PINE, CARIBBEAN HEART PINE, WHITE PINE, and SOUTHERN YELLOW PINE. Vertical and horizontal bamboo are similar in hardness to oak, but the newer stranded bamboo, which offers a completely different look, is extremely hard. Reclaimed antique heart pine and Caribbean heart pine are about as hard as oak. Although used in some restaurants, white pine and southern yellow pine are extremely soft.

This may be too technical for most selecting a wood floor specie, but everyone needs to be aware that all species were not created equally. The differences you can expect between specie may be noticed in the depth of compression marks in the wood from dog claw scratches, a pot being dropped on edge in the kitchen, or the depth of high heel compression marks from a guest with worn off heel caps. Compression will occur, but the depth of the compression mark is determined by hardness of species. Finish wear will occur regardless of the species.

As discussed, solid wood flooring expands and contracts as humidity levels change. Species differ in stability as they do in hardness, and the wider the plank, the larger the seasonal gap will be in the heating season. Antique heart pine and American cherry are the most stable with respect to seasonal movement. Oak, walnut, and ash are average, but hickory and beech are the most unstable of domestic hardwood species. Don’t allow wood flooring stability to affect your specie selection though, the differences are minor. As an example, comparing 4” American cherry to hickory, in the dead of winter when the heat system is cranking, a large seasonal gap in the cherry flooring may be the width of a dime, and the gap in hickory might be the width of a penny.

Transfer of Moisture
By: Jeff Johnson Feb 20, 2018 Category: Moisture

Unlike the brick, drywall, or roofing on your home, the wood flooring installed on your floor is breathing. Yes, it is alive! The very product that creates the warm homey feeling that you walk across every day, which should last the life of your home, is constantly in change. Wood is hygroscopic, comprised of millions of tiny open cells, which are like sponges. Depending on moisture in the air, wood fiber is either accepting moisture and growing in dimension or dissipating moisture and shrinking. This process is similar to a person inhaling and exhaling, except wood flooring is transferring moisture, not oxygen.

In most parts of the country, wood flooring is inhaling (accepting moisture) in the spring and summer, and exhaling (dissipating moisture) in the fall and winter. As this occurs, dimensional change takes place potentially resulting in edge compression and swelling in the humid months and shrinkage resulting in gaps between boards in the dry months. However, this action is not limited to finished floor boards; it also affects the very framed structure the boards are attached to, which compounds the movement.

In many wood framed homes, large gaps between floor boards develop over central framing beams in the winter. This is where two independent floor joist systems meet. Instead of shrinking from the exterior walls, these systems pull apart slightly at an interior junction. Also, where warm air is forced through floor vents, the vent slightly restricts airflow and forces super-heated air down the tongues and grooves of individual boards which can cause gaps around the vent.

During the heating season, some of this may be minimized by use of humidification (adding moisture back into the air), however, when outside temperatures are cold and heat is introduced for comfort, solid wood is going to shrink. The wider the boards, the larger the gap will be. Normal seasonal shrinkage is defined as a gap in the heating season which closes during the humid months. A dime-size gap between 2¼" solid floorboards is considered a seasonal gap if it closes in the summer.

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