Glulam Timber Beam Dimensions (ANSI A190.1)
Direct Answer
Structural Glued Laminated Timber (Glulam) under ANSI A190.1 is an engineered heavy timber beam manufactured by face-bonding individual 2x softwood dimensional lumber laminations with structural adhesives. Featuring standardized widths of 3-1/8", 5-1/8", and 6-3/4" and depths in 1.5-inch increments, Glulam beams support spans exceeding 100 feet.
Source: ANSI A190.1-2017 / APA EWS (Structural Glued Laminated Timber)
Specs
| Governing Standards | ANSI A190.1 / ASTM D3737 / APA EWS S475 |
| Western Species Net Widths | 3-1/8" (79 mm) | 5-1/8" (130 mm) | 6-3/4" (171 mm) | 8-3/4" (222 mm) |
| Southern Pine Net Widths | 3-1/2" (89 mm) | 5-1/2" (140 mm) | 7-1/4" (184 mm) | 9-1/4" (235 mm) |
| Standard Lamination Thickness | 1.50 inches (38 mm) per lamination |
| Standard Depths | Multiples of 1.5" (e.g., 6", 7.5", 9", 10.5", 12", 13.5", 15", 16.5", 18", up to 30+") |
| Standard Stress Class | 24F-V4 (2,400 PSI bending stress / 1.8 × 10⁶ PSI MOE) |
| Appearance Classifications | Framing (hidden), Industrial, Architectural, Premium (exposed) |
Manufacturing from 1.5-Inch Dimensional Laminations
Glulam members are built by finger-jointing kiln-dried dimensional lumber into continuous lengths and face-gluing them under heavy hydraulic clamping pressure with waterproof melamine or resorcinol adhesives. Because each lamination is planed to $1.50\text{ inches}$ ($38\text{ mm}$), Glulam beam depth always increases in exact $1.5\text{-inch}$ multiples:
- $4\text{ Laminations}$: $6.0\text{ in}$ ($152\text{ mm}$)
- $6\text{ Laminations}$: $9.0\text{ in}$ ($229\text{ mm}$)
- $8\text{ Laminations}$: $12.0\text{ in}$ ($305\text{ mm}$)
- $10\text{ Laminations}$: $15.0\text{ in}$ ($381\text{ mm}$)
- $12\text{ Laminations}$: $18.0\text{ in}$ ($457\text{ mm}$)
Camber and Structural Efficiency
Unlike solid sawn timber which deflects under heavy roof loads, Glulam beams can be manufactured with a built-in upward curvature (camber, typically $3,500\text{ to } 5,000\text{ ft}$ radius) during adhesive curing. When the full design dead load of the building roof is applied, the beam deflects downward until it sits perfectly flat and horizontal, eliminating unsightly ceiling sagging in open-concept vaulted architecture.