Hardwood Floors Oct/Nov 2019

AT THE SITE

Because of this cut of flooring’s ability to move in all directions, it is very important to ensure the facility receiving end-grain flooring is capable of maintaining a consistent temperature and humidity throughout the year.

swelling. Depending on the size and species of the end-grain blocks, it is not uncommon to have 1/8”-1/4” expansion built into the system throughout the installation. When acclimating end-grain flooring, the customer should be made aware of any built-in seasonal gaps prior to installation of the floor. The easiest way to explain to themwhy you are doing what you are doing, or why their floor is showing gaps after being installed over the summer, is to share the data provided to us by the USDA, Forest Products Laboratory, which suggests the following moisture

content average and ranges for interior wood products, knowing that the low number represents the heating season, and the high number represents the cooling season: • Most areas of the United States; average = 8 percent MC, ranging from 6-10 percent MC • Dry southwestern regions; average = 6 percent MC, ranging from 4-9 percent MC • Damp, warm coastal areas; average= 11 percent MC, ranging from 8-13 percent MC Actual interior moisture content conditions in any location may differ significantly from these numbers. g Brett Miller is VP of Education & Certification at the National Wood Flooring Association in St. Louis. He can be reached at brett.miller@nwfa.org.

Off-site conditioning of the flooring material in a controlled environment is possible when the off-site conditions reflect the expected in-use (normal living) conditions. In facilities that do not have the ability to maintain a consistent climate control with their HVAC system, shrink/ swell should also be accounted for within the installation. End-grain flooring often requires expansion space (3/4”) to not only be left around the perimeter of the room and at all vertical obstructions, but should also be added within the flooring system. The amount of internal spacing is based on the season of installation and the tangential shrink/swell value of the species being installed. It is not uncommon for many end-grain installations taking place during the heating seasons to be installed with a slight gap between each block to allow for seasonal

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