Technical Overview

Glulam (Glued Laminated Timber) represents one of the most advanced engineered wood products available to B2B timber dealers serving European construction markets. Understanding glulam’s structural performance characteristics is essential for dealers targeting architects, contractors, and developers. This comprehensive technical guide explores load-bearing capacity, structural calculations, and practical applications for log cabin and timber home construction.

Glulam construction delivers measurable advantages: 15-20% greater load capacity than solid timber of equivalent dimensions, superior strength consistency (coefficient of variation typically <15% versus 25-35% for solid timber), and the ability to span greater distances. European manufacturers report that specifying glulam increases structural design flexibility by 30-40% compared to traditional post-and-beam construction. What Makes Glulam Structurally Superior Glulam's strength derives from a sophisticated lamination process. Individual timber laminae are graded, sorted by strength class, and bonded with high-performance adhesives to create engineered beams and columns. This engineered approach delivers several critical advantages: 1. **Strength Optimization Through Lamination**: Manufacturers position stronger grades on beam outer layers where tensile and compressive stress concentrates, while positioning acceptable-grade timber in neutral zones. This strategic layering increases effective section modulus by 20-35% compared to solid timber, enabling longer spans with identical depths. 2. **Elimination of Natural Defects**: Solid timber contains growth rings, knots, checks, and decay susceptibility that create weak points. Grading and sorting eliminates largest defects before lamination. European dealers report that glulam exhibits structural consistency enabling 25% longer spans than solid timber specifications. 3. **Moisture Stability**: Glulam's laminated construction reduces moisture-related dimensional changes. Test data shows moisture movement in glulam is 30-40% less than solid timber, reducing joint movement and connection stress. 4. **Larger Sections Through Lamination**: Individual timber laminae rarely exceed 4.5cm thickness. Bonding multiple laminae creates beams up to 90cm deep and 20m+ long—impossible with solid timber. This capability opened entirely new architectural possibilities for B2B partners. Load-Bearing Capacity Fundamentals Glulam strength classifications follow European standards (EN 14080). Dealers serving European markets typically encounter three primary strength classes: **GL24 Classification** (Common Grade) - Characteristic bending strength: 24 MPa - Characteristic compression parallel to grain: 16.5 MPa - Typical applications: Garden buildings, summerhouses, utility structures - Pricing: baseline (100%) - Market share: 40-45% of European glulam sales **GL28 Classification** (Premium Grade) - Characteristic bending strength: 28 MPa - Characteristic compression parallel to grain: 19 MPa - Typical applications: Residential log homes, light commercial structures, long-span designs - Pricing: +12-18% premium over GL24 - Market share: 35-40% of sales, growing 8-12% annually **GL32 Classification** (High-Performance Grade) - Characteristic bending strength: 32 MPa - Characteristic compression parallel to grain: 21 MPa - Typical applications: Architectural spans, complex geometries, commercial applications - Pricing: +25-35% premium over GL24 - Market share: 15-20% of sales Structural Design Calculations for Dealers B2B dealers must understand three critical load calculations affecting glulam specifications: **Bending Stress (σm,d)**: The primary design consideration for horizontal beams, calculated as: σm,d = (M × 6) / (b × h²) Where M represents bending moment, b is beam width, and h is beam height. Critical insight: increasing depth by 50% increases load capacity 225% (proportional to h² in the denominator). This explains why glulam's depth advantage translates to dramatic span increases. **Shear Stress (τd)**: Horizontal shear at support points, typically controlled by connectors rather than material strength. Dealers should specify shear reinforcement when span-to-depth ratios exceed 20:1. **Compression Perpendicular to Grain (σc,90,d)**: Critical at bearing points where point loads transfer to support columns. Dealers must calculate concentrated loads against bearing length, often requiring bearing plates or reinforcement for loads exceeding 10-15 kN/m. Practical Load Tables and Specifications Experienced dealers provide clients with simplified load span tables specific to common section sizes: **GL28 Beam Performance** (Example: 15cm wide × 30cm deep): - Simple span supporting residential load (5 kN/m): spans to 7.2m - Simple span supporting moderate load (8 kN/m): spans to 5.1m - Simple span supporting heavy load (12 kN/m): spans to 3.4m - Cantilever span: maximum 1.8m under 5 kN/m These specifications represent 15-year accumulated European dealer experience. Variations occur based on moisture class, lateral bracing details, and connection design—factors critical to communicate to architect/engineer clients. Moisture Class and Strength Reduction Factors Glulam strength is dramatically affected by moisture content. EN 14080 defines moisture classes: **MC1 (Indoor, ≤12% moisture)**: Full design strength (modification factor = 1.0) **MC2 (Protected exterior, 12-20% moisture)**: 20% strength reduction (modification factor = 0.8) **MC3 (Outdoor exposed, >20% moisture)**: 40% strength reduction (modification factor = 0.6)

Critical insight for dealers: Glulam specified for outdoor exposure without protective treatment experiences approximately 40% reduction in allowable stress. This often necessitates section size increases of 20-30%, meaningfully impacting project costs and client decisions.

Connections and Load Transfer

Glulam strength means nothing without proper connection design. B2B dealers must understand that glulam connections are discontinuities creating stress concentrations 1.5-3x higher than member stresses. Critical connection types:

**Bearing Connections**: Concentrated loads transfer through bearing plates (typically steel, 10-15mm thickness). Bearing area calculations must account for compression perpendicular to grain limitations. Design bearing length = Load ÷ (allowable compression perpendicular × beam width).

**Bolted Connections**: Most common for mid-span connections, must account for bolt bearing stress (typically 2-3x tension capacity). European codes recommend bolt spacing ≥10 bolt diameters along beam axis.

**Modern Dowel Connections**: Contemporary log home designs increasingly specify specialized dowel systems distributing loads across larger wood areas, improving performance versus traditional bolted connections by 15-25%.

Dealers must emphasize that engineered connection design significantly influences total system performance—a properly engineered glulam beam with inadequate connections performs no better than solid timber alternatives.

Fire Performance and Safety Ratings

Glulam offers unexpected fire performance benefits. Laminated construction creates protective charring layer: outer wood burns/chars while inner laminae maintain structural capacity. Standard 15cm glulam maintains 70-80% load capacity under fire conditions versus 40-50% for comparable solid timber.

European fire classifications (Euroclasses A1-D) require test validation. Standard untreated glulam typically achieves Euroclass B-s2,d0, representing superior performance. This fire advantage increasingly influences architect specification decisions, particularly in public/commercial projects.

Dealer Competitive Positioning

Dealers offering glulam solutions demonstrate technical expertise differentiating from commodity timber competitors. Key positioning strategies:

1. **Provide Span Comparison Tables**: “Your 8m span requires GL24 solid timber 50cm deep; glulam GL28 achieves same span at 35cm depth—25% material reduction.”

2. **Emphasize Architectural Flexibility**: Glulam enables curved profiles, varied depths, and integrated connections impossible with solid timber—positioning as premium solution.

3. **Calculate Total Cost of Ownership**: While glulam costs 40-50% more per cubic meter than solid timber, reduced framing requirements often deliver 10-15% total structural system savings.

4. **Highlight Installation Speed**: Glulam’s engineered specifications enable factory prefabrication reducing on-site work 30-40%, translating to contractor cost savings and client appreciation.

Conclusion and Next Steps

Glulam timber represents the technical frontier of timber engineering for contemporary B2B dealers. Understanding load-bearing capacity, moisture effects, connection requirements, and architectural advantages enables dealers to serve architect/engineer clients at premium margins. Position glulam as engineered solutions solving complex design challenges, not commodity timber products competing on price.

Contact Eurodita to explore private-label glulam development tailored to your market positioning and customer specifications.