Glulam (glued laminated timber) and LVL (laminated veneer lumber) are the two dominant engineered timber beam products used in UK structural work. Both outperform solid timber in strength, dimensional stability and predictability, yet they suit different applications. Understanding how they differ helps you specify confidently for extensions, loft conversions, open-plan remodels and new-build frames.
Glulam is made by bonding multiple kiln-dried sawn timber laminates face-to-face, usually in 33–45 mm layers. LVL is manufactured by stacking thin rotary-peeled wood veneers (typically 3–4.5 mm thick) with the grain running largely parallel, then pressing and bonding them under heat. The result in both cases is a product that carries structural loads far more efficiently than a single sawn section of equivalent size — with far less risk of warping, splitting or shrinkage.
Glulam vs LVL vs Solid Timber
Solid C24 sawn timber is the cheapest option but is limited to modest spans (typically ≤4.8 m for domestic floor joists) and is prone to moisture movement. Glulam and LVL both eliminate most of the natural variability that limits sawn sections.
| Property | Solid Timber (C24) | Glulam (GL28h) | LVL (44–66 N/mm²) |
|---|---|---|---|
| Characteristic bending strength | 24 N/mm² | 28 N/mm² | 44–66 N/mm² |
| Modulus of elasticity (mean) | 11,000 N/mm² | 12,500 N/mm² | 13,800–14,500 N/mm² |
| Dimensional stability | Moderate | Good | Very good |
| Max supplied length | ~6 m | Up to 30 m | Up to 24 m |
| Visual appearance | Natural grain, knots | Visible lamination lines, architectural finish available | Veneered, less decorative |
| Cost (supplied, exc. VAT) | £300–£500/m³ | £400–£900/m³ | £500–£1,100/m³ |
| Standard | BS EN 1194 / BS EN 14080 | BS EN 14080:2013 | BS EN 14374:2004 |
Glulam is typically preferred where appearance matters — exposed ridge beams, open-plan structural posts, or visible roof structures. LVL is more common in concealed positions: hidden behind plasterboard, within flat roof build-ups, or as the flanges of I-joists.
Strengths and Grades
Glulam is graded by bending strength class under BS EN 14080:2013. The most common UK grades are:
- GL24h / GL24c — economical grade; appropriate for most domestic applications
- GL28h / GL28c — higher strength, used where spans or loads exceed GL24 capability
- GL32h / GL32c — less common, typically specified for commercial or industrial work
The suffix ‘h’ denotes homogeneous lamination (all laminates the same grade); ‘c’ denotes combined lamination (stronger outer laminates, lower-grade core). For most residential UK projects, GL24h or GL28h is sufficient.
LVL products are not formally graded in the same letter-number system. Manufacturers publish characteristic strength values directly — bending strengths of 44 N/mm² (edgewise) to 66 N/mm² (flatwise) are typical. Always use manufacturer-specific design data, as properties vary between brands. LVL is typically designed to BS EN 14374:2004 and used in Eurocode 5 (BS EN 1995-1-1) timber design.
Spans
Engineered timber beams can achieve spans that would require steel in an equivalent solid timber section. Typical domestic scenarios (indicative only — always get a structural engineer to confirm):
| Scenario | Glulam size | Approximate span |
|---|---|---|
| Single-storey extension ridge beam | 140 × 270 mm | 4.5–5.5 m |
| Loft conversion ridge beam (point loads) | 160 × 360 mm | 5.5–7.0 m |
| Open-plan ground floor (removing a wall) | 140 × 315 mm | 4.5–6.0 m |
| Large bifold door structural head | 90 × 270 mm | 3.5–4.5 m |
LVL with its higher strength often allows a shallower depth for the same span — a meaningful advantage where floor-to-ceiling height is constrained. For equivalent loads, LVL may be 10–20% shallower than a glulam section.
Spans are governed by both bending and deflection (typically limited to span/300 under variable load to Building Regs Part A guidance). Both products are designed under Eurocode 5 (BS EN 1995-1-1) with the UK National Annex.
Appearance
Glulam is architecturally attractive — the lamination lines are visible but create a controlled, regular aesthetic that reads as deliberate rather than structural compromise. Grades with finger-jointed laminates visible on side faces can be specified as an architectural finish. Natural oils, hardwax oils or clear lacquers are typical finishes.
LVL has a fine-grained veneer surface that is less visually interesting. It tends to be used concealed or clad in softwood trim where it is exposed. It should not be confused with CLT (cross-laminated timber), which has its own structural behaviour and visual language.
Cost vs Steel
For spans up to roughly 6–7 m, glulam is often cost-competitive with steel — and sometimes cheaper once you account for fire protection. Structural steel beams require intumescent paint or board encasement to achieve 30- or 60-minute fire resistance under Building Regs Part B; glulam is designed to char at a predictable rate (~0.7 mm/min for softwood), and at sufficient section size can achieve the same rating with no additional protection.
For spans beyond 8–9 m in domestic work, steel becomes harder to beat on price and headroom. Very long glulam members are also harder to manoeuvre on restricted sites.
A rough comparison for a 5.5 m clear span, medium load:
| Option | Typical supplied cost | Fire protection | Total installed cost (indicative) |
|---|---|---|---|
| 203 × 203 UC steel | £280–£420 | £300–£600 (encasement) | £700–£1,100 |
| Glulam 140 × 360 mm | £350–£550 | Nil (inherent) | £600–£900 |
Note these are rough order-of-magnitude figures. Actual costs vary by contractor, region, and structural complexity.
Where Glulam and LVL Are Used
Glulam suits:
- Exposed ridge beams and purlins in vaulted ceilings
- Open-plan ground-floor beams replacing load-bearing walls
- Portal frame structures in agricultural buildings or extensions
- Structural posts in timber frame construction
- Loft conversion hip-to-gable beams
LVL suits:
- Hidden floor and roof beams where section depth is critical
- Structural door and window headers concealed in wall builds
- Flanges and chord members in prefabricated engineered floor systems
- Flat roof structural build-ups
Building Regulations and Standards
Both products fall under Part A (Structure) of the Building Regulations in England and Wales. A structural engineer must size the beam for your specific loads and span. Their calculations will reference:
- BS EN 1995-1-1 (Eurocode 5) — timber structures design standard
- BS EN 14080:2013 — glulam product standard
- BS EN 14374:2004 — LVL product standard
- UK National Annex to Eurocode 5 — UK-specific design parameters
For fire, both are assessed under BS EN 1995-1-2 (fire design of timber structures). Where exposed, specify the charring rate and reduced cross-section method with your structural engineer.
Both glulam and LVL should be supplied with a Declaration of Performance under the Construction Products Regulation and CE marking confirming the structural class. Ask your supplier for the product’s characteristic values before design begins.
