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Guaranteed Quality - AS/NZS 1328

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Home > TECHNICAL INFORMATION > Specifications for Glue Laminated Timber NZ

Specifications for Glue Laminated Timber NZ

Design
Design of structural timber shall be carried out by McIntosh Timber Laminates Ltd using a specialist registered engineer who can demonstrate competence in the design of timber structures in the relevant market place.

Timber
  • Timber for use in glue laminated members shall be plantation grown NZ Radiata Pine (pressure treated to H3 CCA prior to laminating to Hazard class H3 for protection against termite and fungal attack.)
  • Characteristic Strengths and Stiffness for Glulam shall be GL8, GL10 or GL12 as required by the engineer. Ref. Table 1.2 ASNZS 1328:2
  • Laminated members shall be fabricated from laminations not exceeding 45mm in thickness.
  • Moisture content of laminations at the time of gluing shall be between 12 to 14 per cent. The moisture content of adjacent laminations shall not vary by more than 2 percent and the total range of moisture content of all laminations in any single member shall not exceed 4 percent.
Service Class
The Service Class defines the environmental conditions in which the laminated beams may be used.
Service Class Description Environmental Conditions
1 Interior Service Class characterised by moisture content in the materials corresponding to a temperature of 30ºC and relative humidity of the surrounding air only exceeding 65% for a few weeks per year.  For example:  Domestic Houses, Commercial Offices.
2 Exterior - Under Cover Service Class characterised by moisture content in the materials corresponding to a temperature of 20ºC and relative humidity of the surrounding air only exceeding 85% for a few weeks per year.  For example:  Open sheds, exposed beams under soffits, porches, wool scouring plants, laundries.
3 Exterior - Fully Exposed Service Class characterised by climatic conditions leading to higher moisture content than Service Class 2, or where timber is directly exposed to sun and/or rain.
For example:  Marine structures, bridges.
Adhesives
The adhesive used in fabrication shall be Type II (such as melamine fortified urea) for Service Class 1 & 2 (interior use) and Type I (such as unmodified resorcinol) for Service Class 3 (exterior use).  Adhesive components shall be stored, mixed, handled, spread and cured in accordance with the adhesive manufacturer's instructions.

FABRICATION
General
Fabrication shall be in accordance with recognised sound practice, using adequate plant and equipment under the supervision of qualified personnel and shall comply with the recommendations of ASNZS 1328.

Laminations
Laminations shall be planed within 48 hours prior to gluing. The variation in thickness over the entire lamination shall not exceed 0.5mm.

Joints
Laminations shall be pre-glued to the full length required.  All end joints in laminations shall be structural finger joints complying with the requirements of AS5068. Concentrations of end joints shall be avoided.  End joints shall, as a minimum, be dispersed so as to avoid stacking of joints. The average distance between finger joints in the same lamination shall be approximately 2.0m

Assembly
It is especially important that machining of laminations be precise, glue spread adequate and uniform and clamping sequences and pressures correct.

Appearance of Finished Members
  • Appearance Grade A shall be a filled and sanded finish where appearance is important. All surface voids are plugged or filled.
  • Appearance Grade B shall be a machine planed finish with occasional skips, blemishes and voids.
  • Appearance Grade C is intended for use in applications where appearance is not important. All blemishes and voids are acceptable.
  • Special finishes such as bandsawn shall be nominated by the specifier.
Connections
All connection hardware shall be prefitted where possible with end-cutting and slotting being carried out in the factory.
 
Protection of Finished Members
  • All glue-laminated members shall be weather protected with a minimum of one coat of approved sealer applied in accordance with the manufacturer's recommendations. End grain shall be sealed with a minimum of two coats of sealer.
  • All surfaces to be coated should be clean, dry and free from all mould, fungi etc
  • Members may be individually or bulk wrapped and during handling and delivery to site care shall be taken to avoid damage that will allow moisture penetration or impair structural efficiency.
Quality Control Testing During Manufacture.
The manufacturer shall supply the results of routine tests done in compliance with requirements for checking glue quality and laminate end-joint strength

Handling
  • Glulam shall not be dropped, jarred or dragged. Care shall be taken to prevent damage to surfaces.
  • Glulam shall be loaded, unloaded and secured during transport by means which does not damage the edges, surfaces or packaging.
  • Care shall be taken not to over-stress Glulam members during transport and erection.
NOTE:Use webbing slings for lifting to avoid damaging Glulam members. Where chains or wire ropes are necessary adequate corner protection must be used. Glulam should be lifted on its edge wherever possible with a suitable spreader used on long members. Locate slings carefully to ensure balanced support and control the Glulam with guy lines when lifting.

Installation
The specialist Contractor shall supply an erection supervisor to oversee the installation of the laminated timber structures. A suitable erection method shall be proposed by the installer. Cranage, scaffolding and erection equipment shall be provided by the Main Contractor.

For further information please contact us on 64-9-2539349 or sales@mcintosh.co.nz
 

 

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Licensed Manufacturers   AS/NZS1328 / AS5068
FSC License Code: FSC-C084824
STIC License: FANZ0001
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64 9 253 9349

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