Construction glossary · Wood framing

What is glulamin construction?

Glulam (glued laminated timber) is an engineered beam made from individual dimensional lumber laminations glued and stacked with the grain running lengthwise, used for long-span beams, ridge beams, and exposed architectural members. In framing it carries spans and loads beyond what sawn lumber or smaller engineered members can handle, and it can be left exposed as finish.

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Updated June 2026 · Reviewed by the Ruh construction team

Lam thickness 1-1/2 inCommon combo 24F-V4Bending Fb 2,400 psiSpans Up to 60+ ft

Glulam section, dimensional lams stacked and glued

The definition

Glulam (glued laminated timber), explained.

Glulam is manufactured by bonding nominal lumber laminations, usually 1.5 in thick, into a single large beam under controlled pressure. Higher-grade laminations are placed at the top and bottom where bending stress is greatest, which is why most glulams are stress rated and directional. A common balanced or unbalanced layup means many beams must be installed with the marked top side up, since flipping a cambered unbalanced beam reduces capacity. Glulams come in standard widths like 3.125, 5.125, and 6.75 in and in depths that step in 1.5 in lamination increments. They are often factory-cambered for floor and roof beams. Compared to LVL, glulam is made in larger custom cross sections, spans farther, and is available in appearance grades suitable for exposed work. In framing it appears as ridge beams, garage and great-room headers, and exposed roof beams. For estimating, glulam is priced per linear foot by width and depth, plus connection hardware and bearing detailing.

How it is measured

Glulam is taken off the framing plan and beam schedule by reading each beam callout for width, depth, length, and appearance grade, for example a 5.125 in x 15 in x 24 ft beam. Quantities roll up as linear feet by cross section, since pricing follows width and depth. Read the schedule for camber direction and the top-up orientation note, and confirm bearing length at each support, commonly 3.5 in or more for a heavy ridge beam, because bearing drives the post and column sizing below. Connection hardware such as column caps, hangers, and bearing plates is counted separately off the connection details. Add length allowance only as the supplier requires; glulams are usually cut to exact ordered length.

Worked example

A worked Glulam (glued laminated timber) example.

Worked example

A roof calls for a 5.125 in x 15 in glulam ridge beam spanning 24 ft between two posts, bearing 3.5 in on each post. The beam itself is 24 ft of linear material, and at an illustrative US price of $26 per linear foot for that cross section the beam is 24 lf x $26 = $624. Add two column caps at an illustrative $45 each, so hardware is 2 x $45 = $90, bringing the supplied assembly to $624 + $90 = $714. Because it is an unbalanced layup, the beam must be installed top side up to keep full capacity. The ordered length is 24 ft 0 in plus the two 3.5 in bearings, so net bearing-to-bearing clear span is 24 ft minus 7 in of bearing, leaving about 23 ft 5 in clear. The estimator confirms width, depth, and bearing against the schedule before ordering.

How Ruh handles it

How Ruh handles Glulam (glued laminated timber).

Ruh reads the framing plan and beam schedule, pulls each glulam callout with its width, depth, length, and appearance grade, and rolls it up as linear feet by cross section priced on your own price book. It surfaces the camber and top-up orientation notes and lists the column caps and bearing hardware as separate lines so the assembly cost is complete. The estimator reviews cross section, span, and bearing and signs off.

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Glulam (glued laminated timber): frequently asked questions

Glulam or LVL, which should I use?+

Use LVL for standard plied beams and headers hidden in framing where fixed thicknesses work. Choose glulam for long spans, large custom cross sections, or exposed architectural beams where appearance grade and camber matter. The engineer or beam schedule makes the call.

Why must some glulam beams be installed top side up?+

Unbalanced glulam layups put the strongest laminations at the bottom for simple-span bending, and they are factory cambered upward. Flipping the beam puts weaker material in tension and reverses the camber, reducing capacity, so the marked top must face up.

Can a glulam be left exposed in a finished room?+

Yes. Glulam is made in appearance grades, including premium, that are smooth and suitable to be left exposed as a finished ridge or roof beam. Specify the appearance grade on the schedule since it changes the price.

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Related terms

LVL Joist Truss Header Rafter

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