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It Pays to Know Your OSB Grade Stamp
To be sure you are getting the proper panel for the job, ensure you
refer to the grade stamp on the panel. The stamp contains important
information including specifications and code requirements that will
assist you in selecting the right panel.
The top of the stamp will bear the name of the agency certifying
panels to performance standards recognized by all major North
American building codes—the National Building Code (BOCA), the
One and Two Family Dwelling Code (CABO), the Standard
Building Code (SBCCI), the Uniform Building Code (ICBO), the
International Building Code (ICC) and the National Building Code
of Canada (NRCC). These codes recognize OSB for various
applications, including single layer floors, roof sheathing, siding,
soffits, subfloors, underlayment and wall sheathing. Panels are
certified by three nationally accredited agencies: TECO, APA and
Below the name of the certification agency will be the name of the
standard, for example PS 2. OSB panels are manufactured to meet
performance criteria set by the U.S. Department of Commerce's PS 2
Performance Standard for Wood-Based Structural-Use Panels. In
Canada, panels must comply with the Canadian Standards
Association's CSA O325 Construction Sheathing or CSA O437 OSB
and Waferboard. All three standards set maximum values for
deflection under load, dimensional stability, and minimum values for
strength, stiffness and lateral nail loads.
Structural Grades and Dimensions
One of three grades - Sheathing, Structural 1 Sheathing, and Single
Floor - will be stamped. Sheathing is for use in construction
applications, such as covering material for roofs, subfloors and
walls. Structural 1 Sheathing is a sheathing panel that meets
additional requirements for cross-panel strength and stiffness. Single
Floor is for use as a combination subfloor and underlayment. Next to
the grade will be numbers for panel thickness and span rating,
indicating allowance for roof and floor spacing respectively.
Bond Durability Classification
One of two exposure categories – Exterior or Exposure 1 -
determines where panels can be used. Exterior panels, fully
waterproof, are designed for permanent exposure to the weather.
Most OSB panels are classified as Exposure 1, suitable for panels
that are not permanently exposed to the weather that must resist
effects of high humidity and moisture during construction delays.
To order OSB panels, the specifier or builder should designate
thickness, trademark grade, span rating, bond durability
classification, dimensions, "square edge" or "tongue-and-groove" as
desired for thicker panels and number of pieces. One glance at the
certification stamp will confirm key requirements.
For additional information about OSB, contact the Structural Board
Association at (416) 730-9090, fax (416) 730-9013 or e-mail
. The SBA Web site (www.osbguide.com) is
another excellent resource.