Hardwood Floors October/November 2017

By Brett Miller HARDWOOD HINTS

How to Account for Expansion Space During Installation

1. Undercut the abutting material to ensure adequate expansion space. For example, undercu ing drywall or plaster may allow you to gain 1/2” of expansion without being concerned with the thickness of the baseboards. Undercu ing any abu ing material takes time, and must be accounted for in the overall job cost. 2. Use cork or elastomeric caulking. e Dimensional Change Coe cient and accompanying calculations in the Moisture and Wood publication and in the Installation Guidelines give you the tools necessary to predict approximately howmuch expansion to expect in solid wood ooring if, or when, the ooring gains moisture a er installation. We are beginning to see more architects and builders specifying ooring installed tight to the walls, without baseboard, otherwise known as “net- t installs.” e following are three options to assist with necessary expansion space during the install:

Cork and elastomeric caulking are resilient materials that will slightly compress when the wood expands. Taking this into account can help compensate for voids and necessary expansion. However, there are variations in the density of cork and elastomeric caulking products, and they will never compress to zero. Never use these products as a substitute for the required expansion space. Always take into account the required expansion space during the installation and compensate as necessary. 3. Strategically place internal expansion into the wood floor. is is also known as using washer rows within the oor. is is a method used where you purposely leave gaps in the oor using spacers (washers or string trimmer line) to accommodate for expected moisture gain. is is very common in gym oor installations, primarily due to the expanse of the entire oor and the uncontrolled conditions of the space from season to season.

the magazine of the national wood flooring association

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