Glulam GL28c
Grade
ASTM ANSI/AITC A190.1 · EN 14080
GL28c = combined (layered) softwood glulam, fm,k = 28 MPa
Most common European beam class: high-grade outer laminations over economical core, optimised for bending.
Values for the GL28c condition
Other Glulam tempers and conditions
Glulam is listed in 9 conditions; see the grade overview at Glulam.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
North American softwood glulam | The standard US/Canadian bending combination (Fb = 24 000 psi allowable-basis, E = 1.8×10⁶ psi) for Douglas fir-larch beams. | — | 8 | 0.8 | — | 0.14 W/m·K |
Combined (layered) softwood glulam, fm,k = 24 MPa | Stronger laminations only in the outer zones — the economical choice for simple bending members loaded about the strong axis. | — | 17 | 0.75 | — | 0.12 W/m·K |
GL24hDefault Homogeneous softwood glulam, fm,k = 24 MPa | The default European strength class: all laminations of the same grade, best when the member is loaded in tension/compression or bending in both directions. | — | 19 | 0.8 | — | 0.13 W/m·K |
GL28cThis page Combined (layered) softwood glulam, fm,k = 28 MPa | Most common European beam class: high-grade outer laminations over economical core, optimised for bending. | — | 20 | 0.75 | — | 0.12 W/m·K |
Homogeneous softwood glulam, fm,k = 28 MPa | Higher-graded laminations for more efficient beams and columns where deflection or bending capacity governs. | — | 22 | 0.8 | — | 0.13 W/m·K |
Homogeneous softwood glulam, fm,k = 30 MPa | Premium softwood class for long-span beams and heavily loaded frames where section depth is limited. | — | 24 | 0.8 | — | 0.14 W/m·K |
Homogeneous softwood glulam, fm,k = 32 MPa | Top softwood class from machine-graded high-stiffness laminations; used for the most demanding spans. | — | 26 | 0.8 | — | 0.14 W/m·K |
GL75h | Beech-lamination glulam for slender, heavily loaded members and long-span trusses where softwood sections become impractically large. | — | 60 | 0.9 | — | 0.17 W/m·K |
laminated bamboo lumber (GB/T 40247 class) | Moso-bamboo strip laminate used in China for beams, decking and architectural panels; higher density and strength than softwood glulam but more moisture-sensitive. | — | 80 | 1.2 | — | 0.18 W/m·K |
What is Glulam GL28c?
Glulam GL28c is Glulam in the GL28c grade — most common European beam class: high-grade outer laminations over economical core, optimised for bending. Glulam GL28c has a tensile strength of 20 MPa (2.83 ksi), weaker than 51% of natural material grades. Elongation at break is 0.75% and the elastic modulus is 12.5 GPa (1.81 Msi). Glulam GL28c has a density of 0.44 g/cm³ (0.0159 lb/in³), lighter than 81% of natural material grades. GL24h is the default condition FabDigit quotes; GL28c is available on request or by drawing note.
Advantages
- Easy to machine — 92/100, better than 97% of natural material grades
- Lightweight — 0.44 g/cm³ (0.0159 lb/in³), better than 81% of natural material grades
Limitations
- Limited service temperature — 50°C (122 °F), worse than 99% of natural material grades
- Low fracture toughness — 0.4 MPa·√m (0.364 ksi·√in), worse than 86% of natural material grades
- Limited ductility — 0.75%, worse than 82% of natural material grades
Glulam GL28c properties
Typical room-temperature values for Glulam GL28c; 13 are specific to this condition. Other listed values are Glulam reference data and may not represent this condition. Bars are the position among natural material grades.
Physical2
Glulam GL28c has a density of 0.44 g/cm³ (0.0159 lb/in³), lighter than 81% of natural material grades.
Mechanical10
Glulam GL28c has a tensile strength of 20 MPa (2.83 ksi), weaker than 51% of natural material grades. Elongation at break is 0.75% and the elastic modulus is 12.5 GPa (1.81 Msi).
Thermal5
Glulam GL28c is rated for continuous service to 50°C (122 °F). It conducts heat at 0.12 W/m·K (0.0693 BTU/hr·ft·°F), worse than 70% of natural material grades. Thermal expansion is 4.5 µm/m·K (2.5 µin/in·°F).
Electrical1
Glulam GL28c has an electrical resistivity of 1×10¹⁰ Ω·m.
Chemical & Environmental1
Corrosion resistance is good (55/100), better than 69% of natural material grades.
Sustainability4
Producing a kilogram of Glulam GL28c takes about 12 MJ of energy and emits 0.55 kg of CO₂ — more than 69% of natural material grades. Typical recycled content is 2%.
Manufacturability2
Glulam GL28c's machinability is excellent (92/100, better than 97% of natural material grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Glulam GL28c
Is Glulam easy to machine?
Cuts, drills and CNC-routes readily with carbide tooling; glue lines dull HSS quickly and dust extraction is essential.
Can Glulam be welded?
Not weldable — members are joined with slotted-in steel plates, dowels, screws or glued-in rods per Eurocode 5 / NDS.
Can Glulam be formed, bent or molded?
Curved beams are produced by bending thin laminations (typically t ≤ R/200) over a form and clamping while the adhesive cures under controlled temperature and humidity.
What surface finishes work on Glulam?
Sand, then apply penetrating oil, alkyd/acrylic coating or fire-retardant/preservative treatment; end grain and exposed tops need flashing or capping.
Glulam chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| cellulosesoftwood lamination wood substance | 40 – 47 | 43 |
| hemicellulose | 22 – 30 | 26 |
| lignin | 25 – 32 | 28 |
| extractives/ashresins, terpenes, minerals | 1 – 5 | 2 |
| structural adhesive (MUF/PRF/PUR)glue lines + finger joints, EN 301/EN 15425 Type I | 0.5 – 2.5 | 1.2 |
| moistureEN 14080 requires 6–15 % at gluing | 8 – 15 | 12 |
| wood substance | balance | — |
Glulam GL28c — frequently asked
What is Glulam GL28c used for?
Glulam GL28c is typically used for exposed structural beams, arches/domes, bridges, long-span roofs and columns. In short: long-span structural timber; curved beams to shape; stronger than sawn timber.
What is the tensile strength of Glulam GL28c?
Glulam GL28c has a typical tensile strength of 20 MPa (2.83 ksi) — weaker than 51% of natural material grades. Strength varies by condition: see the 9 listed tempers.
Is Glulam GL28c easy to machine?
Yes — machinability is rated excellent (92/100, better than 97% of natural material grades). Cuts, drills and CNC-routes readily with carbide tooling; glue lines dull HSS quickly and dust extraction is essential.
Can Glulam GL28c be welded?
Not weldable — members are joined with slotted-in steel plates, dowels, screws or glued-in rods per Eurocode 5 / NDS.
What surface finishes work on Glulam GL28c?
Sand, then apply penetrating oil, alkyd/acrylic coating or fire-retardant/preservative treatment; end grain and exposed tops need flashing or capping.
Can Glulam GL28c be formed, bent or molded?
Curved beams are produced by bending thin laminations (typically t ≤ R/200) over a form and clamping while the adhesive cures under controlled temperature and humidity.
What is the maximum service temperature of Glulam GL28c?
Glulam GL28c is rated for continuous use to about 50°C (122 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- EN 14080:2013 Timber structures — Glued laminated timber and glued solid timber — CEN (2013)
- ANSI/AITC A190.1 Structural Glued Laminated Timber — APA/AITC (2017)
- Wood Handbook — Wood as an Engineering Material (FPL-GTR-190) — USDA Forest Products Laboratory (2010)
- Eurocode 5 (EN 1995-1-1/1-2) design values and thermal data — CEN (2004)
- Glulam beam technical data (GL24h/GL28c) — Moelven / Binderholz / Pollmeier BauBuche (2023)
- Inventory of Carbon & Energy (ICE) v3 — glulam — Circular Ecology (2019)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.