Laminated Veneer Lumber Span Chart

Laminated veneer lumber (LVL) beams carry more load over longer spans than ordinary lumber of the same size. Enter the span, the tributary width and the loads, and this estimator checks common LVL depths and ply counts for bending, shear and deflection using typical 2.0E design values — a way to understand the size range before you get a manufacturer’s calculation or an engineer’s design.

What LVL is

Laminated veneer lumber is an engineered wood product made from thin wood veneers glued together with their grain running in the same direction, then pressed into billets and cut to size. The process disperses knots and defects, so LVL is stronger, straighter and more consistent than sawn lumber of the same dimensions. It is widely used for beams, headers over doors and windows, ridge beams and rim boards. LVL is commonly 1¾ inches thick per ply, and plies are fastened together to make wider beams — two plies make a 3½-inch beam.

How LVL beams are sized

1. Work out the loads: the live load (people, furniture, snow on roofs) and dead load (the weight of the structure) in pounds per square foot.
2. Multiply by the tributary width — the width of floor or roof the beam supports, usually half the joist span on each side — to get a load per foot of beam.
3. Check bending: the beam’s bending stress must stay below the allowable value (Fb).
4. Check shear near the supports against the allowable shear stress (Fv).
5. Check deflection: the beam must not sag more than the code limit, often span/360 for floor live load.
6. Check bearing length at each support so the wood under the beam is not crushed.

The estimator performs the bending, shear and deflection checks for a simply supported beam with a uniform load, using typical published LVL design values. It does not check bearing, point loads, lateral stability, load duration, notches or holes.

Why a “span chart” is only a starting point

Every LVL manufacturer publishes its own design values and load tables, and they differ. Tables also depend on the load case (floor or roof, snow load, point loads from posts above), the deflection limit, the support conditions and the building code. Two beams that look alike on paper may carry different loads. That is why building departments usually require LVL beams to be sized with the manufacturer’s software or by a registered design professional, and why the estimates here should be used to understand the likely size range and to discuss options — not to specify the beam.

Typical LVL sizes

Common depths include 5½, 7¼ and 9¼ inches (matching sawn lumber for headers), and 9½, 11⅞, 14, 16 and 18 inches (matching I-joist depths so beams sit flush with the floor). Longer spans and heavier loads call for deeper beams or more plies; depth is far more effective than width because stiffness rises with the cube of depth.

Worked example

A beam spans 14 feet and supports floor joists spanning 12 feet on one side and 12 on the other, so the tributary width is 12 feet. With 40 psf live and 15 psf dead load, the uniform load is 660 lb/ft. The estimator finds the maximum moment is about 16,170 lb·ft and checks the options: with typical 2.0E values, a 2-ply 1¾ × 11⅞ in LVL passes bending, shear and L/360 deflection (deflection at about 91% of the limit), while a 2-ply 9½ in fails both bending and deflection. A single 1¾ × 16 in ply sits right at the bending limit, so the 2-ply 11⅞ or 2-ply 14 in would be the more comfortable choices to discuss. A manufacturer’s calculation would confirm the size, bearing lengths and fastening schedule.

Installing multi-ply LVL beams

• Fasten plies together with nails, screws or bolts in the pattern the manufacturer specifies — especially for side-loaded beams.
• Provide the required bearing length at each end, often several inches on posts or walls.
• Do not notch, drill or cut LVL beams except as allowed in the manufacturer’s guidelines.
• Keep LVL dry during storage and construction; it is not rated for exposed exterior use unless treated for it.
• Use hangers and connectors rated for the loads.

LVL vs other beams

Point loads and posts

The estimator assumes a uniform load spread along the beam. Posts, girder trusses or bearing walls landing on the beam create point loads that can govern the design, and they must be carried down through the structure to the foundation. If anything bears on the beam other than evenly spaced joists, the manufacturer’s software or an engineer should analyse it.

Privacy

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