Engineered Wood Products: LVL, Glulam, I-Joists & CLT Explained

Why Engineered Wood?

Engineered wood products (EWPs) are manufactured from wood fibers, veneers, or lumber laminated together with structural adhesives. They solve three problems that limit solid lumber: inconsistent quality (knots, grain deviations), dimensional instability (warping, twisting, shrinking), and limited span capability (large solid timbers are expensive and hard to source). Modern construction increasingly relies on EWPs for structural framing.

LVL (Laminated Veneer Lumber)

What it is: Thin wood veneers (typically 1/8" to 1/10" thick) glued together with grain running parallel. Think of it as plywood where all the grain goes the same direction, creating a beam rather than a panel.

Strengths: Extremely consistent — no knots or weak spots. Can be made in virtually any length. Higher allowable stress values than same-size solid lumber. Won't warp, twist, or bow. Available in widths from 1.75" to 7".

Common uses: Headers over windows and doors (most common use in residential), beam and girder applications, hip and valley rafters, scaffold planks, garage door headers.

Span capability: A double 1.75" x 11.875" LVL can span up to 14 feet as a header. Triple LVL beams span even further. Always check manufacturer's span tables for your specific loading conditions.

Cost: $3-6 per linear foot for standard sizes. More expensive than solid lumber per piece but often cheaper overall because fewer pieces are needed and installation is faster.

Glulam (Glue-Laminated Timber)

What it is: Layers of dimensional lumber (laminations) glued together with structural adhesive under pressure. The laminations run parallel, creating beams that can be straight, curved, or tapered.

Strengths: Available in massive sizes — 6" to 24" deep and up to 100+ feet long. Stronger than same-size solid timber. Can be curved for architectural applications (arches, vaulted ceilings). Appearance-grade available for exposed beam applications.

Common uses: Long-span ridge beams, exposed cathedral ceiling beams, commercial and industrial framing, bridge construction, post-and-beam structures, heavy timber frames.

Span capability: A 5.125" x 12" glulam beam can span 20+ feet depending on loading. For heavy loads or long spans, glulam is often the most cost-effective structural solution.

Cost: $5-15 per linear foot depending on size and grade. Appearance-grade (stainable, no finger joints on visible faces) costs 20-40% more than framing grade.

Wood I-Joists

What it is: An I-shaped cross-section with LVL or solid lumber flanges (top and bottom) connected by an OSB or plywood web (vertical center). The I-shape provides maximum strength with minimum material — the same engineering principle as steel I-beams.

Strengths: Span up to 30+ feet without intermediate support. Lightweight — one person can carry a 24-foot I-joist. Pre-engineered knockouts for plumbing and HVAC runs. Dead straight — no crowning, bowing, or twisting. No squeaky floors from shrinkage.

Common uses: Floor joists (the most common application), roof rafters, long-span ceiling joists. I-joists have largely replaced solid 2x10 and 2x12 floor joists in new construction.

Sizes: Depths from 9.5" to 16" (some manufacturers make 20" and 24"). Flange widths of 1.75" (fits 2x4 bearing) or 2.5" (fits 2x6 bearing).

Cost: $2-5 per linear foot. Often cheaper than the solid lumber they replace when factoring in longer spans (fewer beams needed) and faster installation (no culling or crowning).

PSL (Parallel Strand Lumber)

What it is: Long strands of wood veneer (up to 8 feet long) aligned parallel and bonded with adhesive under heat and pressure. Sold under the brand name Parallam. Distinctive straw-like strand pattern.

Strengths: Available in large column and beam sizes. Excellent for posts and columns where concentrated loads are high. Consistent and predictable — no weak spots from knots or grain deviation.

Common uses: Posts and columns (especially tall or heavily loaded), beams, headers, garage door headers. Often used where a single structural member must carry large concentrated loads.

Cost: $6-12 per linear foot. More expensive than LVL but available in larger cross-sections and better for column applications.

CLT (Cross-Laminated Timber)

What it is: Large panels of dimensional lumber layered in alternating directions (like plywood but with solid lumber layers instead of veneers) and bonded with structural adhesive. Panels can be massive — up to 10 feet wide, 60 feet long, and 20 inches thick.

Strengths: Can replace concrete and steel in mid-rise buildings (up to 18 stories in some jurisdictions). Excellent seismic performance — ductile and lightweight compared to concrete. Carbon-sequestering — stores carbon rather than emitting it during production. Fast installation — panels are CNC-cut to exact dimensions including window and door openings.

Common uses: Multi-story mass timber buildings, floor and roof diaphragms, shear walls, elevator shafts. Increasingly popular for commercial buildings, schools, and multi-family housing pursuing green building goals.

Cost: $15-30 per square foot installed. More expensive than conventional wood framing but competitive with steel and concrete for mid-rise construction when factoring in faster construction schedules.

Choosing the Right Product

For headers and short beams: LVL — most cost-effective, widely available, easy to work with standard tools.

For long-span beams and exposed applications: Glulam — available in large sizes, appearance grades, and custom curves.

For floor and roof framing: Wood I-joists — longest spans with lowest weight, built-in utility chase, no shrinkage squeaks.

For columns and posts: PSL — best load-bearing capacity in column applications.

For walls, floors, and roofs as panels: CLT — the emerging option for mass timber and green building construction.