Technical Guide

NeXTimber by Timberlink manufactures Australian-made Engineered Wood Products (EWP): Cross Laminated Timber (CLT) panels and Glue Laminated Timber (GLT) members, from responsibly sourced Australian plantation radiata pine processed in Tarpeena, South Australia.

CLT is machine-graded, kiln-dried softwood finger jointed and arranged in 3, 5, 7 or 9 alternating perpendicular layers, glued on face and edge and cured under pressure into a solid panel (billet), then CNC machined. The cross-laminated layup gives rigidity in two directions, suiting subfloors, walls, floors, shafts and roofs. GLT laminates finger-jointed layers in one grain direction, suiting beams, columns and portal frames.

NeXTimber does not provide structural engineering design or certification. Its technical team offers advisory support on design, connection details and specification; the project's engineer certifies the structure. NeXTimber owns shop drawings, take-offs, refined panelisation and supply.

All structures must meet the National Construction Code (NCC) performance requirements, satisfied by a Performance Solution, a Deemed-to-Satisfy solution, or both. NeXTimber CLT complies with AS 1720.1 through Clause 1.3.1(h) (other timber products and grades), with characteristic properties established by test or report; AS 1720.1 does not explicitly cover the CLT design procedure, so designers determine section properties by industry-accepted methods and apply strength and serviceability checks. NeXTimber GLT is manufactured to AS/NZS 1328.1 and designed to AS 1720.1.

CLT is not referenced in the New Zealand Building Code (NZBC); designers demonstrate stability and durability via an Alternative Solution pathway, drawing on references such as the FPInnovations CLT Handbook (2019), ProHolz CLT Structural Design Volumes 1 and 2, and the Swedish Wood CLT Handbook (2019).

Pre-analysis tables give indicative panel sizes for floors, roofs and walls to inform panel selection and project budgets before detailed design. They are prepared using the Shear Analogy Method (FPInnovations CLT Handbook 2019, WoodSolutions Design Guide 50) for ambient conditions only. The tables are not structurally certified: the project engineer must undertake a full analysis and a separate fire load assessment for the project's FRL period. Floor spans account for vibration, which governs longer spans in mass timber.

Connections are critical to the structure and are the responsibility of the project's structural engineer to design, detail and specify. Capacities are determined to AS 1720.1 or Eurocode 5, or from the supplier's European Technical Assessments (ETA). Self-tapping or self-drilling screws are generally preferred over bolts and brackets for cost, speed and ease of installation.

Partially threaded screws suit most floor and wall connections where elements need to be squeezed together. Fully threaded screws give higher tensile capacity but do not clamp, so they are used for reinforcement or where high tensile capacity is required, often in combination with partially threaded screws. Meeting minimum edge and end distances is critical, especially when connecting to steel elements. Typical CLT and GLT connections include panel-to-panel spline and half-lap joints, ridge-beam connections, wall-to-floor, beam-to-panel, beam connections and post-base connections. NeXTimber can supply specified connection hardware, prepare fixing take-offs, and provide a lifting solution with pre-installed lifting devices.

Fire. Fire resistance capacity is assessed by a registered testing authority to AS 1530.4. The melamine adhesive maintains glue-line integrity and a constant linear char rate, avoiding premature char fall-off. See the Fire Performance Guide for char rates and FRL detailing.

Acoustics. Because mass timber is lightweight, acoustic performance is met by adding mass, resilient separation and isolation, and by controlling flanking paths. See the Acoustic Performance Guide for tested wall and floor systems.

Moisture. In well-designed structures the in-service moisture content sits at 10-14%, below the 20% fungal-decay threshold. CLT's mass gives slower drying, so detailing matters. Even H3-treated CLT should not be used in external, above-ground or weather-exposed applications, and H3 is not a substitute for robust waterproofing. A typical building envelope uses a vapour-permeable membrane, insulation, a drained and ventilated cavity and cladding.