Page 12 - ProInstallerJanuary-February 2022

Wood:

Identifying Wood Distortions &

Corrections

By Brett Miller, NWFA Vice President Technical Standards, Training & Certification

ood floors are a product of nature. They are • Maintenance-related issues, including:
produced from living organisms—trees—and like • Wet-mopping resulting in standing/topical liquid
Wall living organisms, respond to the environment moisture left on the floor.
in which they are placed. In fact, wood floors literally
change every day. Most of these changes are subtle and • Use of steam mops/cleaning devices.
undetectable, but there are times when the changes can • Use of non-breathable rugs on the floor.
be very noticeable—or even destructive. Three of the most
commonly noticeable and/or destructive changes that can • Not maintaining relative humidity levels year-round.
be experienced by wood floors include cupping, crowning • Wood flooring installed at a lower moisture content
and dry cupping. than the in-use conditions allow.
• Wood flooring installed in an environment drier than
the in-use conditions.
• Over-wetting the wood when water mopping, applying
wood bleach, or reactive conditioners. Over-wetting
would be described as liquids running down the cracks
between the boards.
• Slight cupping/edge-lift can occur with normal
application of water-based sealers and finishes,
water-based stains and water-soluble dyes, or with
application of multiple coats of water-based finish
Cupping in one day, prior to previously applied coats being
Identification adequately dried.
Cupping is a concave or dished appearance of individual • Slight cupping/edge-lift can occur when floors have
boards with the edges of the board raised higher than the been damp-mopped in dry-climate conditions.
center. • Solid flooring may cup when a wood floor experiences
conditions that cause rapid drying on the surface.
Causes • Cupping can occur with use of water-based adhesive
Cupping typically is caused by dramatic fluctuations under floors not recommended with these types of
in temperature and/or humidity, which can include the adhesives.
following: • Cupping also can occur prior to installation, as follows:
• A moisture imbalance through the thickness of the
board; the wood usually has a higher moisture content • Improper or unmanaged handling of the environmental
on the underside than on the top. conditions surrounding the flooring material after it
• An increase in moisture conditions, including: was manufactured, either during transport, while in
storage or while acclimating at the jobsite.
• Inadequate or inoperable HVAC systems, resulting in • Engineered flooring manufactured out of balance (core
elevated humidity levels. and wear layer having an unbalanced EMC).
• Wet subflooring (wood or concrete slab).
• Inadequate moisture control systems installed beneath Cures
the wood floor. Never attempt to repair a cupped floor until all of the
• Poor building drainage resulting in rainwater runoff or sources of moisture have been located and eliminated. Photos courtesy of National Wood Flooring Association
subsurface groundwater. The moisture content of the solid wood floor must be
• Moisture from inadequately ventilated or at equilibrium with the expected in-use (normal living)
unconditioned crawl spaces or basements. conditions prior to resanding a cupped floor. As long as
• Portable water sources/appliances, building leaks or the wood is not permanently deformed or damaged, the
plumbing leaks. flooring should return to its original shape and size when
it returns to its original moisture content. This process
Continued
12 PROINSTALLER MAGAZINE • JANUARY/FEBRUARY 2022