Specifying Glulam and CLT for Australian and New Zealand Projects

How NeXTimber manufactures GL13 glulam and CLT in Australia

NeXTimber makes glulam and CLT locally, which is what puts stocked sections within reach of a specification. It is part of Timberlink, one of Australia's largest structural pine sawmills, and draws its feedstock from that supply. The engineered wood plant sits at the Tarpeena sawmill in South Australia, with a second mill at Bell Bay in Tasmania. Distribution centers in Perth, Adelaide, Melbourne, and Sydney hold product close to each capital. The plant was built through 2021 and 2022 and produced its first commissioned panels in early 2023.

The two products differ in makeup. NeXTimber CLT uses MGP10 timber in every layer, cross-laminated for two-way structural behavior. The glulam is offered in a single grade, GL13, built from a combination of MGP10, MGP12, and MGP15. The higher-strength lamella sits on the outer faces, where bending stress is greatest. Both are finger-jointed from framing-pine lamella and bonded with a tested structural adhesive. Panels reach up to 16 m long, 3.5 m wide, and 360 mm thick in 10 mm increments. In practice 12 m is the limit for a standard truck bed.

Manufacturing detail matters for how the finished panel behaves. NeXTimber edge-glues and face-glues its lamella, then sands every panel, so the surface is cleaner than an unsanded industrial grade, though not furniture grade. The radio frequency press allows a non-delaminating structural adhesive. In a fire, that adhesive holds the outer lamella in place until the section chars. That behavior supports the fire resistance levels published in the technical guides.

Why locally stocked sections change how you specify glulam and CLT

A specification only holds if the section on the drawings is one a builder can actually buy. When a nominated grade or size is not stocked, it gets substituted at procurement or sent back for re-approval. The design drifts out of the engineer's control. NeXTimber's answer is to keep the range narrow and available. Glulam comes in one grade, GL13, in cambered and straight profiles, and every listed section size is held at all four distribution centers.

That availability changes the timeline. Once a GL13 size is specified, a builder can order it through a retailer and have it within a day or two. There is no waiting weeks for a grade that is out of stock. Specifying a stocked section from the start is what keeps the design intact from drawings through to the build.

Compliance pathways, fire, and acoustics

All NeXTimber glulam and CLT is CodeMark certified, and the glulam is manufactured to the Australian glulam standard, with characteristic values published in the technical guides. The timber is responsibly sourced under FSC and PEFC certification. Environmental product declarations support sequestered-carbon claims for Green Star pathways.

Fire behavior follows the building class. In Class 2 to 9 buildings, timber generally must be fire-protected. A fire engineer can develop a performance solution that exposes the timber, using NeXTimber's test data. The technical guides give fire resistance levels for both protected and exposed cases, and the protected values are considerably higher. Acoustics need attention too. A bare CLT floor carries sound, so most designs add a topping or a battened subfloor, which also creates a cavity for services.

A worked GL13 example in Calcs.com

Ben Cox specified NeXTimber's GL13 glulam directly in Calcs.com, where the sections are built into the timber calculators. The range covers widths from 65 mm through to 630 mm, in lengths from 2.4 m to 12 m in 600 mm steps. Cambered sections carry a "C" prefix and are designed with a built-in camber that offsets long-term deflection.

The camber earns its place in the numbers. A straight 336 x 65 section showed around 13 mm of long-term deflection in the worked example. The cambered version of the same section dropped under 10 mm and passed. Long-term deflection is handled through the deflection limit, the same way as other timber products in Calcs.com. For CLT, the technical-guide span tables cover floors, walls, and roofs. As a guide, a 360 mm panel spans roughly 8 m simply supported under a 2 kPa live load. The free Spec Toolbox software covers cantilevers and unequal spans.

Designing mass timber for manufacture and assembly

Mass timber rewards decisions made early. More design up front means fewer parts on site and a faster, simpler build. NeXTimber manufactures panels to a 2 mm tolerance and cuts penetrations, lap joints, and complex profiles on a CNC line, so what arrives matches what was modeled. That precision is what makes design for manufacture and assembly work in practice.

The projects Ben Cox showed put the approach to work. On King Island, where skilled labor is scarce, panels were freighted in and erected in days to weeks. A townhouse development in Preston, Melbourne used CLT stairs, usable during installation and dressed later. The structure went up in a few weeks. A Monash University student accommodation building pairs a concrete podium with five levels of CLT floors and glulam beams and columns. In each case, the labor and program savings on site are the argument for choosing timber.