|
For a full specification please download our "Specification for Laminated Timber."
Essential Information
McIntosh Timber Laminates Ltd. is a NZ pioneer of Glulam structures and is a qualified manufacturer under ASNZS 1328 Glue Laminated Structural Timber License No 2061 and ASNZS Finger Jointed Structural Timber License No 2354.
Species
NZ has vast resources of renewal plantations cultivating Radiata Pine making this an environmentally responsible construction material. This material has an even texture with a low proportion of heartwood. It is moderately strong and has excellent machining, gluing and nailing properties. While not naturally durable it is ideally suited to long life treatments. Other species such as Douglas Fir, Macrocarpa, Lawson's Cyprus are also available.
Grading
McIntosh Timber Laminates Ltd. was the first manufacturer in New Zealand to install a unique E GRADER that guarantees the designer specified stiffness and strengths are achieved. Visual over rides can also be applied to limit knot sizes and other timber characteristics for appearance grade items.
Design Values
The design values for laminated timber are set out in ASNZS 1328 Table 1.2 - see table below. The most common grade for NZ Glulam is GL8. However McIntosh Timber Laminates Ltd.'s unique E GRADER enables the efficient production of GL10 beams, providing a more effective beam cross section. GL12 beams can be produced in limited quantities from NZ grown Radiata.
Characteristic Strengths and Elastic Moduli for Glulam Grades
| Characteristic Strengths (MPa) | Elastic Moduli (Mpa) | | GL Grade | Bending | Tension parallel to grain | Shear in Beam | Compression parallel to grain | Short modulus of elasticity parallel to the end grain | Short duration modulus of rigidity for beams | | GL 12 | 25 | 12.5 | 3.7 | 29 | 11500 | 770 | | GL 10 | 22 | 11 | 3.7 | 26 | 10000 | 670 | | GL 8 | 19 | 10 | 3.7 | 24 | 8000 | 530 |
Service Classes
Definition of Environmental Conditions for Glulam Service Classes
Service Class Description Environmental Conditions
| Service Class | Description | Environmental Conditions | | 1 | Interior | Service Class characterised by moisture content in the materials corresponding to a temperature of 30 ºC 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 20º C 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. |
Treatment
For interior use the most suitable treatment is a surface coating after manufacture. With its high percentage of sapwood Radiata Pine is ideally suitable for full penetration pressure treatment. This will achieve treatment levels from H1 to H5 providing life long resistance to fungal and insect attack - even in external exposure. For Glulam exposed to the elements McIntosh Timber Laminates Ltd. recommends the use of pre-treated CCA. ACQ or Copper Azole timber. LOSP treatment of finished Glulam beams is possible, however if this material is used externally a paint coat is necessary to ensure durability. In all cases if Glulam beams are cut on site the exposed ends must be re-coated.
Kiln Drying
Only kiln dried material is used in McIntosh Glulam. With a moisture content of 12 - 16% maximum stability is ensured in finished Glulam products.
Finger Jointing
Continuous laminations are produced up to any length using Structural finger joints to ASNZS 1492. In-house quality control testing ensures consistent strength is achieved. The unique McIntosh finger joint system allows the use of the longest length of in-grade timber. In this way the distance between finger joints in a lamination can be up to 6m. The average distance between finger joints in each lamination is 2.3m. This contrasts to the normal use of short shooks used by other manufacturers where the average length may be as short as 400mm.
Adhesives
Table 1.4 of ASNZS 1328 shows the appropriate adhesives for the various exposure categories.
Manufacture
Manufacture is carried out to the demanding requirements of ASNZS 1328 and is regularly inspected by the NZ Timber Certification Board.
Using specialised heavy duty equipment McIntosh has an ongoing programme of keeping up with Glulam technology. Our modern factory is equipped with three overhead gantries enabling the efficient handling of large finished Glulam members.
Current machinery includes:-
Purpose Built Finger Jointer
"E" Grader
Weinig EL30 moulder
5" Bandsaw
Kupfermule 2000mm x 300mm beam planer
Straight and Curved Pressing Beds - up to 40m long
Triple Drum Sander 900mm
Wood Turning Lathe - up to 10m long
Morticers, Portable Bandsaws, Spindle Moulder, Deep-cut Skill Saws, Sanders, Hand-planers, Rebaters, etc.
Finishing
Appearance grades are detailed in the table below.
Definition of Appearance Grades
| Appearance Grade | Description | | A | This grade is intended for use in applications where appearance of the member is important and clear or painted finishes are used. All surface voids are filled or repaired. Unless it is specified otherwise, the surfaces shall be sanded to a minimum of 60-grit finish. | | B | The grade is intended for use in painted applications where appearance is important but a planed finish is acceptable. The machining shall conform to No. 2 dressed surfaces grade as defined in AS 2796. Occasional skips in the surface are permissible and minor blemishes, voids and machining want shall be acceptable. The outer-most laminations shall be free of loose knots and voids. | | C | This grade is intended for use in applications where appearance is not important. All blemishes and voids are acceptable. |
Once finished the Glulam beams should receive a protective surface coating that is designed to provide temporary weather protection during construction.
For full specification for Laminated Timber click here.
|
