Ways to Minimize Buckling in Wood Sheathing Panels

Buckling is mostly the result of moisture which causes wood sheathing panels to expand. While buckling does little to effect the structural integrity of the OSB panel, it can have a negativePrevent Buckling aesthetic effect which would result in expensive callbacks. Here are some ways in which you can mitigate the effects of buckling by accounting for normal moisture conditions and through moisture control.

Your wood sheathing panels will naturally absorb water until they are in equilibrium with their new environment. From the APA: “In typical sheathing applications, relative humidity may vary between 40 percent and 80 percent, with corresponding equilibrium moisture content of the panels ranging between 6 percent and 14 percent.”

Generally this causes the panels to expand and contract to about 1/8 inch. You must make allowances for this expansion by leaving an 1/8-inch gap between panels. Panels will expand more if directly exposed to moisture. When you store panels onsite during the construction process, keep the panels from getting wet by covering them and keeping them up off the ground.

If the panels do get wet, cut the straps to ensure even expansion and allow them to dry sufficiently before installation.

Design to Reduce Buckling

Panel spacing is an essential element to prevent  buckling, but allowing the panels to acclimate prior to installation will also help. You can get a full guide to on-site panel storage here.

Take care to install OSB sub-flooring  with strength axis at right angles to the joists. OSB roof sheathing should be also installed with the strength axis at right angles to the roof framing rather than parallel to the supports. Remember that your span ratings are based on the proper installation of panels. Ensure that your OSB panels are installed according to your local building code, design professional’s instructions and the manufacturer’s installation instructions.

Check that floor joists, rafters and wall framing are flat, square and level. Buckling of panels can result from improper framing techniques.

Follow proper fastener spacing patterns, use the correct size fastener and ensure that fasteners do not miss underlying supports. Consult your manufacturer or design professional for nail spacing and size.

Moisture Control

Adequate ventilation is essential to dealing with moisture. Follow your local building codes to ensure that any areas such as attics and crawl spaces are correctly ventilated and ensure that your placement of blocking and bridging does not interfere with the movement of air.

Keep attic and soffit vents clear. Baffling should be installed to keep insulation from clogging vent openings.

Where suitable, use a vapor barrier to prevent moist air from entering the home.

Properly seal all light fixtures, plumbing fixtures and other holes.

Vent all appliances like dryers, bath and kitchen fans to the outside rather than into the attic, basement or crawl spaces.

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