Hardwood Floors April/May 2017

AT THE SITE

Starting from the Bottom (Continued)

MAXIMUM JOIST SPAN RATING

MINIMUM SUBFLOOR PANEL PERFORMANCE CATEGORY 19/32” (15.1 mm) plywood or 23/32” (18.3 mm) OSB

16” (406mm)

19.2” (488 mm) 24” (610 mm)

23/32” plywood or OSB 7/8” plywood or OSB

IDENTIFICATION OF PROPER SUBFLOOR PANELS BASED ON THE JOIST SPANS

When installing wood flooring, follow the information in the chart above (from NWFA Installation Guidelines) in order to understand which subflooring material is required to proceed with wood floor installation. SUBFLOOR PANELS

Subfloor panels should follow the most current standards: U.S. Voluntary Product Standard PS1 Construction and Industrial Plywood, and/or U.S. Voluntary Product Standard PS2, or Canadian Standards CSA 0151 or CSA 0121, and/or Canadian Performance Standard O325 (Reference R503.2 of the 2015 IRC; 2305.1.5 of the 2015 IBC). Wood structural panels suitable for use as subflooring material should be plywood or oriented strand board (OSB) with a bond classification of Exposure 1 or Exterior. When using OSB subfloors, keep these things in mind: • OSB thickness varies and will be determined by joist type, span, and anticipated load. • OSB is composed of more than 95 percent wood. • Most OSB is manufactured with bonding resins and waxes compressed with 1,100 pounds per square inch pressure and heat. • Some OSB is edge-sealed to repel water. Without this, OSB is prone to swell on the edges. • In general, OSB has lower moisture tolerances. • OSB is typically more cost effective. • OSB requires 1/8” spacing between all panels, on all four sides. • OSB shrinks/swells nearly twice as much in width as it does in its length.

Top photo: 23/32” OSB. Bottom photo: 19/32” plywood.

60 hardwood floors www.hardwoodfloorsmag.com