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Q.The building codes don't allow you to rip graded lumber to a narrower width (to make a 2x6 and a 2x4 out of a 2x10, for example). But what about ripping LVL?

A.You're right about ripping graded lumber. Doing so "relocates" strength-reducing characteristics that affect performance, and effectively voids the grade designation (see illustration). It's different with LVL, which is a more consistent material. Manufacturers rip it as standard practice when producing beams. LVL is made in billets up to 48 inches wide that are ripped to commercially available standard depths. It's okay to rip LVL beams to a smaller depth, too, though you'll have to recalculate the beam capacity. Sizing software supplied by manufacturers (TJ Beam, for example) provides a sizing override where you can enter a non-standard depth to determine the load-carrying capacity of a ripped LVL.

Why you can't rip graded lumber...

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Ripping a piece of graded lumber to make a narrower beam is disallowed by code because it may place strength-reducing characteristics like knots close to the edge of the board, compromising bending strength.

Paul Fisette is director of Building Materials and Wood Technology at the University of Massachusetts at Amherst and a JLC contributing editor.