Hardwood Flooring February March 2018

Hardwood flooring installation Follow the recommendations of the NWFA for handling, storing, acclimating, and installing hardwood flooring. Installation of the flooring material onto the subfloor requires significant consideration of the job site, including ambient temperature and relative humidity at the time of installation. Where possible, hardwood flooring strips should be oriented perpendicular to floor framing for maximum floor stiffness. APA, in cooperation with the NWFA, created the following checklist, for floor installers to ensure the best long-term performance of the floor system. Floor installer’s checklist: Seven steps to minimize the risk of moisture 1. Be sure to have a vapor barrier membrane in place on the crawlspace ground and ventilate/condition the crawlspace or basement prior to wood floor installation. 2. Consider methods to remove excessive moisture from the framing/floor sheathing and the rest of the interior of the building prior to installing the flooring (such as using an auxiliary dehumidifier in the short term). 3. Follow the recommended fastener schedule or consider augmenting the attachment by spacing the fasteners at closer intervals. For example, if the recommendations for fastening are 8” to 10” apart, keep fasteners no further than 8” apart. 4. Make sure that the length and diameter of the flooring fasteners meet or exceed flooring industry or the manufacturer’s recommendations. Flooring manufacturers typically recommend a minimum length of fastener. The greater the length of the fasteners’ embedment in the wood subfloor or the larger the shank diameter of the fasteners, the greater the fastener withdrawal capacity. 5. The recommendation for fastening of flooring boards is often within 1” to 3” of end joints. Keeping fasteners within 1” to 2” of end joints will better stabilize movement. 6. Consider using an approved flooring adhesive in conjunction with the recommended fastener schedule for flooring being installed with a liquid vapor- retarding system to control moisture migration. 7. In some situations, it may be necessary to build in expansion rows within the flooring system. This may include built-in gaps within the floor, t-molding transitions, cork, or other methods. Useful Resources: The following resources are available to assist in the planning, preparation, and proper installation of hardwood flooring over wood panel subflooring. These and other resources can be found on APA’s website at apawood.org. • APA’s EngineeredWood Construction Guide (Form E30) • APA’s EngineeredWood Floor Systems Construction Guide (Canada; Form R300) • APA’s Technical Note: APA Performance Rated Panel Subfloors under Hardwood Flooring (Form R280) • APA’s Technical Note: Prevent Callbacks inWood Flooring Installation (FormT350)

EXPOSURE 1 THICKNESS 0.578 IN. RATED SHEATHING 40/20 SIZED FOR SPACING 000 PS 2-10 SHEATHING HUD-UM-40 19/32 CATEGORY

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CONSTRUCTION SHEATHING 2R40/2F20

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15mm CSA O325-16

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1. Panel grade 2. Span Rating 3. Sized less than full length/width 4. Bond classification Decimal thickness 5.

designation (this value is generally at or near the lower tolerance specified in PS 1 or PS 2) Mill number 6. 7. 8. Performance Category 9. Product Standard HUD recognition Panel grade, Canadian standard Panel mark—Rating and end-use designation per the Canadian standard Canadian performance rated panel standard Panel face grain orientation indicator

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Figure 1: Dissecting the APA Trademark.

Mark Halverson has served as a manager for APA since 1994, starting with management of industrial markets and then moving on to management of APA’s field staff. In this capacity, Mark oversees a team of engineers, architects, and technical experts who provide engineered wood and systems information and recommendations to construction and design professionals. He can be reached at mark.halverson@apawood.org.

the magazine of the national wood flooring association

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