Size a glulam beam for span and load. Compare standard glulam depths and widths to find the right beam for your project.
Glued laminated timber (glulam) is an engineered wood product made by bonding layers (laminations) of dimensional lumber. Glulam combines the beauty of natural wood with engineered-grade strength and is available in sizes and lengths far exceeding solid sawn lumber. It's the go-to product for exposed beams, long-span ridge beams, and heavy-load applications.
This glulam sizing calculator helps you select the right beam width and depth for a given span and load. It uses typical 24F-V4 DF/DF glulam properties (Fb = 2,400 psi, E = 1,800,000 psi) and checks both bending stress and L/360 live-load deflection.
Glulam is manufactured in standard widths (3.125″, 3.5″, 5.125″, 5.5″, 6.75″) and depths in 1.5″ increments (since each lamination is 1.5″ thick). This gives a wide range of available sizes to optimize for your specific requirements.
Precise calculations are essential for meeting regulatory requirements, passing inspections, and ensuring the long-term structural integrity and safety of the completed project.
Glulam is ideal for exposed beams and long spans where appearance matters. This tool helps you quickly find the minimum depth and width to carry your load across the desired span. This quantitative approach replaces rule-of-thumb estimates with precise calculations, minimizing material waste and reducing the likelihood of costly change orders during construction.
S_req = M × 12 / Fb, where M = wL²/8 I_req from 5wL⁴/(384EI) = L/360 Min depth (bending): d = √(6 × S_req / b) Min depth (deflection): d = ³√(12 × I_req / b)
Result: Minimum 5.125″ × 19.5″ glulam (13 laminations)
At 24 ft span, 300 plf: M = 300×24²/8 = 21,600 ft-lbs = 259,200 in-lbs. S_req = 259,200/2,400 = 108 in³. d_bending = √(6×108/5.125) = 11.3″. Deflection requires ~18.9″. Round up to 19.5″ (13 laminations × 1.5″).
24F-V4 DF/DF is the most common residential grade: Fb = 2,400 psi, E = 1,800,000 psi, Fv = 265 psi. 24F-V8 SP/SP is a Southern Pine alternative with slightly different properties. 20F-V7 is a lower grade sometimes used for purlins and secondary members.
Concealed connections are popular for exposed glulam: knife plates, concealed beam hangers (Simpson CCQ), and through-bolted connections. For heavy loads, steel plates and through-bolts provide the highest capacity. Always use the connector manufacturer's published values.
Glulam typically costs 30–60% more than LVL per lineal foot at equivalent capacity. The premium buys appearance-grade finish, wider standard widths, and longer available lengths. For concealed beams in floor systems, LVL is usually more cost-effective.
Glulam is made from stacked layers of dimensional lumber (horizontal laminations), giving it a natural wood appearance. LVL is made from thin rotary-peeled veneers (like plywood but in beam form). LVL is narrower (1.75″ per ply) and typically used in concealed applications.
3.5″ fits inside a 2×4 wall; 5.125″ fits inside a 2×6 wall. For exposed beams, 5.125″ or 6.75″ are common. The wider the beam, the shallower it can be for the same load, but wider beams cost more.
Yes, with proper treatment and finishing. Specify "industrial appearance with preservative treatment" for outdoor structural applications. Seal the end grain and apply a UV-protective finish. Re-coat every 2–3 years.
Glulam is not symmetrical—the bottom laminations are higher-quality tension-rated wood. The TOP stamp indicates which face must be installed facing up. Installing it upside down significantly reduces its capacity.
Residential glulam beams commonly span 20–32 ft. For commercial and heavy-timber construction, glulam can span 60–100+ ft in arched or truss configurations. The maximum span depends on depth, width, grade, and loading.
Glulam requires adequate bearing area at supports. A minimum 3.5″ bearing length is typical for light loads; heavy loads may need 5″+ or a bearing plate to distribute the reaction. Use Simpson concealed-beam connectors (?"CCQ, HUC) for clean installations.