Glulam Beams: Strength, Fire and Carbon Data for Designers

Glulam turns small sawn boards into long, deep, sometimes curved structural members. Architects choose it for exposed beams, columns, portal frames and long roof spans.

This guide sets out what the EPDs, standards pages and peer-reviewed papers we could read say about glulam beams, and where they stop. Most numbers come from manufacturers, so we label them as such.

What is glulam and how is it made?

Laminations, finger joints and glue

Hasslacher describes glulam as a rod-shaped timber element of at least two dried softwood lamellas bonded parallel to the fibres.^[1] EN 14080:2013 sets performance requirements for glulam for buildings and bridges. It also covers production requirements, conformity attestation and marking, and it excludes products treated with fire retardants.^[4] The standard covers four products: glulam with laminations of 6 to 45 mm, glued solid timber with two to five laminations of 45 to 85 mm, glulam with large finger joints and block glued glulam.^[4]

In the Hasslacher process, boards are graded visually or mainly by machine, defects are cut out, and the boards are finger-jointed into endless lamellas before gluing and pressing.^[1] The glue is a small share of the product: Hasslacher states about 1.5 % melamine-urea-formaldehyde (MUF) adhesive, Rubner 1 to 2.5 % split roughly 40 % MUF, 20 % melamine and 40 % EPI, and Moelven about 1 % MUF.^[1][2][3] The 2026 EPD of the German glulam association (Studiengemeinschaft Holzleimbau) lists MUF at 1.52 % and polyurethane (PUR) at 0.07 %, and its text says phenol-resorcin and EPI adhesives are used in smaller proportions.^[10]

Strength classes

Hasslacher lists standard classes GL20h, GL24h, GL24c, GL28h, GL28c, GL30h, GL30c, GL32h, GL32c, GL36h and GL36c. For its range, it gives characteristic tensile strength parallel to grain of 15 to 28.8 N/mm² and a mean modulus of elasticity of 10,400 to 15,750 N/mm².^[1] For class GL24h, Rubner declares bending strength 24 N/mm², tensile strength parallel 19.2 N/mm² and modulus of elasticity 11,500 N/mm².^[2] Confirm class, species and the declared values on the supplier's declaration of performance for your project.

How does glulam perform?

Fire

Both Hasslacher and Rubner declare Euroclass D, smoke class s2 and no flaming droplets (d0).^[1][2] Hasslacher adds that fire gas toxicity corresponds to natural wood and gives a burn rate of 0.70 mm/min for beams and columns and 0.65 mm/min for ceilings, with a zero-strength layer of 7 mm.^[1] Structural fire design in Europe follows Eurocode 5, EN 1995-1-2, which covers timber structures in fire.^[5] The two rates and the 7 mm layer match Table 3.1 and the reduced cross-section method of EN 1995-1-2 as reproduced in a 2012 European Commission JRC workshop presentation: 0.65 mm/min (one-dimensional) and 0.7 mm/min (notional) for glued laminated softwood of at least 290 kg/m³, and d0 = 7 mm.^[12] National annexes can change values, so take the design rate from the version applicable to your project. We did not read the standard text itself.

Moisture and service class

Hasslacher states that glulam, with the exception of glued solid timber, can be used in service classes 1 to 3 under EN 1995-1-1, and that chemical preservative is unusual and permitted only if structural protection is not enough.^[1] The product is delivered at about 12 % moisture, so detailing must keep it dry on site.^[1] We found no independent durability measurement for exposed glulam in the sources we read.

Thermal and acoustic behaviour

The 0.12 W/(m·K) conductivity^[1][2] is roughly three times the 0.038 to 0.041 W/(m·K) in the manufacturer datasheets summarised in our wood fibre insulation profile, so thermal bridging at beam ends needs the same care as for any timber member. We found no sourced acoustic data for glulam.

How much carbon does glulam hold?

What the EPDs show

Under EN 15804+A2, the tree's uptake of CO₂ counts as a negative biogenic term in the production stage. Hasslacher states 212 kg of carbon stored per m³ of glulam, equal to about 779 kg CO₂.^[1] Its A1–A3 GWP-total is −694 kg CO₂e per m³, made of +81.3 fossil and −776 biogenic. At end of life the EPD models energy recovery in a biomass plant, which releases +779 kg of biogenic CO₂ in C3 and credits −386 in module D.^[1] Rubner's 2023 EPD follows the same pattern with −687 in A1–A3 and +771 in C3.^[2] Moelven's A1–A3 total is −674 and its C3 value +751.^[3]

Read the number with care

The three EPDs differ in density (462 to 480 kg/m³), product mix, background database and rules for biogenic carbon, so do not rank suppliers by their totals. Moelven's EPD states that the net biogenic carbon cycle across modules A to C is zero.^[3] Its own A1–A3 rows (fossil +52.4, biogenic −744, land use +0.365) add up to about −691, not the stated −674, so we use only its stated totals.^[3] Hasslacher's production uses 100 % green electricity at a factor of 0.03 kg CO₂e/kWh, so its EPD names timber supply and resin, not electricity, as the main drivers.^[1] All three are manufacturer-owned declarations that name an independent verifier.^[1][2][3]

Two peer-reviewed papers help put the figures in context. A 2025 study of Japanese glulam production, using data from 12 factories covering 58.1 % of national output, found that lamina manufacturing (38 %), transport (27 %) and electricity (21 %) were the main sources of greenhouse gas emissions. Adhesive type had a relatively minor effect, and the choice of allocation method changed the reported emissions significantly.^[6] A 2014 Chalmers study compared glulam roof beams with steel frames and found clear advantages for glulam in all comparable scenarios except one, in which steel frames are recycled and average steel production is substituted, where impacts were similar. In absolute terms, whether glulam is recycled or incinerated mattered a great deal.^[7] Both are read from abstracts only, and the Japanese data do not describe European products.

Which standards and certificates apply?

EN 14080:2013 is the product standard, valid from 5 August 2013 on the Estonian catalogue page, and it falls under the Construction Products Regulation (EU) 305/2011.^[4] The EPDs state that placing glulam on the EU market needs a declaration of performance and CE marking.^[1] Eurocode 5 covers design: EN 1995-1-1 for common rules and EN 1995-1-2 for fire.^[1][5] The catalogue page for EN 1995-1-2 lists EN 1995-1-2:2005 with a corrigendum valid from 7 August 2009, an earlier version with the Estonian national annex (2006) and a draft revision.^[5] Only catalogue pages were read, not the standard texts.

Moelven's 2022 EPD lists PEFC and FSC management systems, ISO 9001 and ISO 14001 for its Töreboda plant.^[3] In the FSC certificate database on 8 October 2026, Moelven Limtre AB at Bruksgatan 8, Töreboda is a valid site on group certificate DNV-COC-000538 of Moelven Industrier ASA (licence FSC-C113012, valid until 2 October 2027). Certificate SCS-COC-003672, held by Moelven Töreboda AB at the same street address, was terminated in 2017. We could not see a Töreboda site on group certificate DNV-COC-000624 of Moelven Wood AS, which the register shows as terminated in August 2026.^[13] The EPD names the owner Moelven Töreboda AB at Fabriksgatan 8, so confirm with Moelven that the valid entry covers the glulam you specify. The PEFC database sat behind a bot check, so we did not check it.

Where is glulam used, and what are the limits?

Where has glulam been used in real projects?

The project below is documented by architect-credit and library-database pages. We found no independent monitoring data for it. We left out the Tamedia headquarters in Zurich because none of the pages we read describe its structure as glulam.

Where to buy glulam in Europe

Frequently asked questions about glulam

The bottom line on glulam

Glulam is a well-documented structural timber with EN 14080 as its product standard, strength classes up to GL36h, Euroclass D and EPDs that show negative production-stage carbon. Its limits are combustibility, moisture exposure on site and carbon figures that depend on end-of-life assumptions. Ask each supplier for the current EPD, the declaration of performance for your strength class and the registry entry for any certificate it cites.

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