When installing engineered lumber joists (such as I-joists) in California residential construction, what specific requirement must be met regarding web stiffeners?
Correct Answer
B) Web stiffeners must be installed at all bearing points and concentrated load locations per manufacturer specifications
CRC Section R502.1.1 requires that engineered lumber products be installed according to manufacturer specifications. All I-joist manufacturers require web stiffeners at bearing points and concentrated loads to prevent web crippling. California's strict adherence to manufacturer specifications is critical for seismic performance and structural integrity.
Why This Is the Correct Answer
CRC Section R502.1.1 requires engineered lumber to be installed per manufacturer specifications. All major I-joist manufacturers require web stiffeners at bearing points (where the joist rests on a wall or beam) and at concentrated load locations (where a point load from above bears down on the joist). Without stiffeners at these locations, the thin OSB web can buckle or crush — a failure mode called web crippling — which is catastrophic. California's seismic environment makes this requirement especially critical.
Why the Other Options Are Wrong
Option A: Web stiffeners are only required at bearing points over 8 feet
Requiring web stiffeners only at bearing points over 8 feet is an invented rule with no basis in the CRC or manufacturer specifications. Web crippling is a function of concentrated force, not span length. A short-span joist under a point load needs stiffeners just as much as a long-span joist.
Option C: Web stiffeners must be installed every 4 feet along the span
Installing web stiffeners every 4 feet along the span regardless of load conditions is not a code or manufacturer requirement. Web stiffeners are located in response to specific structural conditions (bearing points and concentrated loads), not at uniform intervals. Uniform interval stiffening would add unnecessary cost.
Option D: Web stiffeners are not required if the span is less than 16 feet
Eliminating the web stiffener requirement for spans under 16 feet is incorrect. Span length does not determine the need for web stiffeners; the presence of bearing points and concentrated loads does. A 10-foot joist still needs stiffeners at its supports.
Memory Technique
Web stiffeners go where the joist is squeezed: at bearing points (squeezing from below) and at concentrated loads (squeezing from above). Think 'stiffener where it gets pinched.'
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