NZS AS 1720.1:2022 (Excludes AS Text)
Timber Structures
Standard sets out general requirements for the verification of timber structures and elements. It includes calculation methods and design data appropriate for commonly encountered structural elements and materials. This New Zealand standard is an adoption with national modifications and has been reproduced from AS 1720.1:2010 Timber structures Part 1: Design methods (Incorporating Amendments No. 1, 2, and 3), and supersedes NZS 3603:1993. A list of modifications can be found under ‘Foreword’ section of the standard.
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NZS AS 1720.1:2022 Timber structures Part 1: Design methods
Committee representation
Acknowledgement
Copyright
CONTENTS
Referenced documents
Latest revisions
Review of standards
Foreword
Appendix ZZ – Variations to AS 1720.1:2010 for New Zealand
ZZ1 SCOPE AND GENERAL
ZZ1.1 Scope and application
ZZ1.3 Timber
ZZ1.4 General design considerations
ZZ1.5 Design and supervision
ZZ1.7 Definitions
ZZ1.8 Notation
ZZ1.10 Abbreviations
ZZ2 DESIGN PROPERTIES OF STRUCTURAL TIMBER ELEMENTS
ZZ2.2 Design properties
ZZ2.3 Capacity factor
ZZ3 DESIGN CAPACITY OF BASIC STRUCTURAL MEMBERS
ZZ4 DESIGN CAPACITIES OF JOINTS IN TIMBER STRUCTURES
ZZ4.0 General
ZZ4.1 Simplified method – Nails, screws, bolts, and coach screws
ZZ4.2 Simplified method – Design of nailed joints
ZZ4.3 Simplified method – Design of screwed joints
ZZ4.4 Simplified method – Design of bolted joints
ZZ4.5 Simplified method – Design of coach-screwed joints
ZZ4A.1 Detailed method – Nails, screws, rivets, bolts, dowels, and coach screws
ZZ4A.2 Detailed method – Definitions
ZZ4A.3 Detailed method – Design considerations
ZZ4A.4 Detailed method – Material properties
ZZ4A.5 Detailed method – Configuration parameters
ZZ4A.6 Detailed methods – Withdrawal strength
ZZ4A.7 Detailed methods – Lateral strength
ZZ4A.8 Deformation
ZZ4.8 Other types of mechanical fasteners
ZZ4.9 Glued joints
ZZ5 PLYWOOD
ZZ6 ROUND TIMBERS
ZZ6.1 General
ZZ6.2 Characteristic properties and elastic moduli
ZZ6.3 Design
ZZ6.4 Modification factor k21 for trimming (peeling or shaving)
ZZ6.5 Modification factor k23 for preservative treatment involving steaming
ZZ6.6 Modification factor k22 for seasoned use conditions
ZZ6.7 Effective sections
ZZ7 GLUE-LAMINATED TIMBER CONSTRUCTION
ZZ8 STRUCTURAL LAMINATED VENEER LUMBER (LVL)
ZZ8.3 Design properties
ZZ9 SEISMIC DESIGN
ZZ9.1 Scope
ZZ9.2 Structural design requirements
ZZ9.3 Seismic design actions
ZZ10 FLOOR AND ROOF DIAPHRAGMS
ZZ10.1 Scope
ZZ10.2 General principles and design requirements
Appendix
APPENDIX ZZC – Joints in timber structures
APPENDIX ZZE – Further design methods for members
APPENDIX ZZF – Notation and factors
Appendix ZZG – Miscellaneous design information
APPENDIX ZZH – Design properties for structural graded timber
TABLES
Table ZZ2.1 – Characteristic properties for New Zealand-verified timber
Table ZZ2.2 – Properties for New Zealand non-verified timber
Table ZZ3.1 – Material constant (ρb) for sawn timber beams
Table ZZ3.2 – Material constant (ρc) for sawn timber columns
Table ZZ4.1 – Limitations on timber joints for nails, screws, bolts, and coach screws
Table ZZ4.2 – Residual member brittle failures and strengths at a joint
Table ZZ4.3 – Capacity factors used in joint strength equations
Table ZZ4.4 – Factor k15 for nails, rivets, screws, bolts, dowels, and coach screws where in-service timber moisture content can exceed 15%
Table ZZ4.5 – Minimum end distance for parallel-to-grain loading
Table ZZ4.6 – Minimum end distance for perpendicular-to-grain loading
Table ZZ4.7 – Fastener yielding failure and strength for single-shear joints
Table ZZ4.8 – Fastener yielding failure and strength for double shear joints
Table ZZ4.9 – Fastener group brittle failure and strength for parallel to grain loading – Small dowel-type fasteners
Table ZZ4.10 – Member fastener group brittle failure and strength for perpendicular-to-grain loading – Small dowel-type fasteners
Table ZZ4.11 – Effective thickness factor for elastic wood failure (Cr)
Table ZZ4.12 – Fastener yielding failure and strength for single-shear joints
Table ZZ4.13 – Fastener yielding failure and strength for double-shear joints
Table ZZ4.14 – Fastener group brittle failure and strength for parallel-to-grain loading – Large dowel-type fasteners
Table ZZ4.15 – Member fastener group brittle failure and strength for perpendicular-to-grain loading – Large dowel-type fasteners
Table ZZ4.16 – Duration-of load-factor (k37)
Table ZZ5.1 – Characteristic properties for structural plywood (moisture content 15% or less)
Table ZZ6.1 – Characteristic properties (MPa) and modulus of elasticity (GPa) for naturally round softwood timber in unseasoned condition
Table ZZ6.2 – Peeling or shaving factor (k21)
Table ZZ6.3 – Preservative treatment involving steaming factor (k23)
Table ZZ6.4 – Seasoned use factor (k22)
Table ZZ7.1 – Characteristic values for structural design – GL grades (moisture content 15% or less)
Table ZZ8.1 – Characteristic values for design – Structural LVL used ‘on-edge’ (moisture content 15% or less)
Table ZZ9.1 – Strain or deformation limits for specific potential ductile elements
Table ZZ9.2 – Maximum structural ductility factor (µ) for ULS loading
Table ZZE1 – Material constant (ρb) – Seasoned timber beams
Table ZZE2 – Material constant (ρb) – Unseasoned timber beams
Table ZZE3 – Material constant (ρc) – Seasoned timber columns
Table ZZE4 – Material constant (ρc) – Unseasoned timber columns
Table ZZF1 – Quantity symbols
Table ZZF2 – Modification factors for strength (k)
FIGURES
Figure ZZ4.1a – Configuration requirements – Load applied parallel to grain – Member in tension
Figure ZZ4.1b – Configuration requirements – Load applied parallel to grain – Member in compression
Figure ZZ4.2a – Configuration requirements – Load applied perpendicular to grain – End joint
Figure ZZ4.2b – Configuration requirements – Load applied perpendicular to grain – Internal
Figure ZZ4.3 – Minimum nail spacing in radiata pine sawn timber
Figure ZZ4.4 – Definition of connection, joint, and member
Figure ZZ4.5 – Example of the maximum distance perpendicular to grain when in-service shrinkage or swelling of timber is likely, unless consideration is given to limit shrinkage stresses
Figure ZZ4.6a – Configuration definitions – Load parallel to grain – Member in tension
Figure ZZ4.6b – Configuration definitions – Load parallel to grain – Member in compression
Figure ZZ4.7a – Configuration definitions – Load perpendicular to grain – End joint
Figure ZZ4.7b – Configuration definitions – Load perpendicular to grain – Internal joints
Figure ZZ4.8 – Nail diameters
Figure ZZ4.9a – Applicable thickness of members in nailed joints – Single shear
Figure ZZ4.9b – Applicable thickness of members in nailed joints – Single shear
Figure ZZ4.9c – Applicable thickness of members in nailed joints – Double shear
Figure ZZ4.10a – Minimum spacing of nails – No pre-boring
Figure ZZ4.10b – Minimum spacing of nails – No pre-boring – Sawn radiata pine only
Figure ZZ4.10c – Minimum spacing of nails – Pre-bored to 0.8D
Figure ZZ4.11 – Screw diameters
Figure ZZ4.12a – Applicable thickness of members in screwed joints – Single shear
Figure ZZ4.12b – Applicable thickness of members in screwed joints – Single shear
Figure ZZ4.12c – Applicable thickness of members in screwed joints – Double shear
Figure ZZ4.13 – Minimum screw spacing requirements
Figure ZZ4.14 – Example of rivet dimensions meeting the requirements of ZZ4A.5.4.1
Figure ZZ4.15a – Rivet joint thicknesses and penetration definitions – Member loaded on one surface
Figure ZZ4.15b – Rivet joint thicknesses and penetration definitions – Member loaded on two surfaces
Figure ZZ4.16 – Applicable thicknesses of members in bolt or dowel connection
Figure ZZ4.17 – Minimum bolt spacing requirements – Parallel to grain
Figure ZZ4.18 – Minimum bolt spacing requirements – Perpendicular to grain
Figure ZZ4.19a – Separation of side members in dowel joints
Figure ZZ4.19b – Separation of side members in dowel joints – One possible prevention measure
Figure ZZ4.20 – Applicable thickness of timber member for a coach screw laterally loaded
Figure ZZ4.21 – Minimum coach screw spacing requirements – Parallel to grain
Figure ZZ4.22 – Minimum coach screw spacing requirements – Perpendicular to grain
Figure ZZ4.23 – Load-deformation curve for fastener group and failure modes
Figure ZZ4.24 – Example of possible member brittle failures of all fastener groups in a joint
Figure ZZ4.25 – Example of possible brittle failures of all fastener groups
Figure ZZ4.26 – Loaded surface factor (KLS) values
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NZS AS 1720.1:2022 Timber structures Part 1: Design methods
Committee representation
Acknowledgement
Copyright
CONTENTS
Referenced documents
Latest revisions
Review of standards
Foreword
Appendix ZZ – Variations to AS 1720.1:2010 for New Zealand
ZZ1 SCOPE AND GENERAL
ZZ1.1 Scope and application
ZZ1.3 Timber
ZZ1.4 General design considerations
ZZ1.5 Design and supervision
ZZ1.7 Definitions
ZZ1.8 Notation
ZZ1.10 Abbreviations
ZZ2 DESIGN PROPERTIES OF STRUCTURAL TIMBER ELEMENTS
ZZ2.2 Design properties
ZZ2.3 Capacity factor
ZZ3 DESIGN CAPACITY OF BASIC STRUCTURAL MEMBERS
ZZ4 DESIGN CAPACITIES OF JOINTS IN TIMBER STRUCTURES
ZZ4.0 General
ZZ4.1 Simplified method – Nails, screws, bolts, and coach screws
ZZ4.2 Simplified method – Design of nailed joints
ZZ4.3 Simplified method – Design of screwed joints
ZZ4.4 Simplified method – Design of bolted joints
ZZ4.5 Simplified method – Design of coach-screwed joints
ZZ4A.1 Detailed method – Nails, screws, rivets, bolts, dowels, and coach screws
ZZ4A.2 Detailed method – Definitions
ZZ4A.3 Detailed method – Design considerations
ZZ4A.4 Detailed method – Material properties
ZZ4A.5 Detailed method – Configuration parameters
ZZ4A.6 Detailed methods – Withdrawal strength
ZZ4A.7 Detailed methods – Lateral strength
ZZ4A.8 Deformation
ZZ4.8 Other types of mechanical fasteners
ZZ4.9 Glued joints
ZZ5 PLYWOOD
ZZ6 ROUND TIMBERS
ZZ6.1 General
ZZ6.2 Characteristic properties and elastic moduli
ZZ6.3 Design
ZZ6.4 Modification factor k21 for trimming (peeling or shaving)
ZZ6.5 Modification factor k23 for preservative treatment involving steaming
ZZ6.6 Modification factor k22 for seasoned use conditions
ZZ6.7 Effective sections
ZZ7 GLUE-LAMINATED TIMBER CONSTRUCTION
ZZ8 STRUCTURAL LAMINATED VENEER LUMBER (LVL)
ZZ8.3 Design properties
ZZ9 SEISMIC DESIGN
ZZ9.1 Scope
ZZ9.2 Structural design requirements
ZZ9.3 Seismic design actions
ZZ10 FLOOR AND ROOF DIAPHRAGMS
ZZ10.1 Scope
ZZ10.2 General principles and design requirements
Appendix
APPENDIX ZZC – Joints in timber structures
APPENDIX ZZE – Further design methods for members
APPENDIX ZZF – Notation and factors
Appendix ZZG – Miscellaneous design information
APPENDIX ZZH – Design properties for structural graded timber
TABLES
Table ZZ2.1 – Characteristic properties for New Zealand-verified timber
Table ZZ2.2 – Properties for New Zealand non-verified timber
Table ZZ3.1 – Material constant (ρb) for sawn timber beams
Table ZZ3.2 – Material constant (ρc) for sawn timber columns
Table ZZ4.1 – Limitations on timber joints for nails, screws, bolts, and coach screws
Table ZZ4.2 – Residual member brittle failures and strengths at a joint
Table ZZ4.3 – Capacity factors used in joint strength equations
Table ZZ4.4 – Factor k15 for nails, rivets, screws, bolts, dowels, and coach screws where in-service timber moisture content can exceed 15%
Table ZZ4.5 – Minimum end distance for parallel-to-grain loading
Table ZZ4.6 – Minimum end distance for perpendicular-to-grain loading
Table ZZ4.7 – Fastener yielding failure and strength for single-shear joints
Table ZZ4.8 – Fastener yielding failure and strength for double shear joints
Table ZZ4.9 – Fastener group brittle failure and strength for parallel to grain loading – Small dowel-type fasteners
Table ZZ4.10 – Member fastener group brittle failure and strength for perpendicular-to-grain loading – Small dowel-type fasteners
Table ZZ4.11 – Effective thickness factor for elastic wood failure (Cr)
Table ZZ4.12 – Fastener yielding failure and strength for single-shear joints
Table ZZ4.13 – Fastener yielding failure and strength for double-shear joints
Table ZZ4.14 – Fastener group brittle failure and strength for parallel-to-grain loading – Large dowel-type fasteners
Table ZZ4.15 – Member fastener group brittle failure and strength for perpendicular-to-grain loading – Large dowel-type fasteners
Table ZZ4.16 – Duration-of load-factor (k37)
Table ZZ5.1 – Characteristic properties for structural plywood (moisture content 15% or less)
Table ZZ6.1 – Characteristic properties (MPa) and modulus of elasticity (GPa) for naturally round softwood timber in unseasoned condition
Table ZZ6.2 – Peeling or shaving factor (k21)
Table ZZ6.3 – Preservative treatment involving steaming factor (k23)
Table ZZ6.4 – Seasoned use factor (k22)
Table ZZ7.1 – Characteristic values for structural design – GL grades (moisture content 15% or less)
Table ZZ8.1 – Characteristic values for design – Structural LVL used ‘on-edge’ (moisture content 15% or less)
Table ZZ9.1 – Strain or deformation limits for specific potential ductile elements
Table ZZ9.2 – Maximum structural ductility factor (µ) for ULS loading
Table ZZE1 – Material constant (ρb) – Seasoned timber beams
Table ZZE2 – Material constant (ρb) – Unseasoned timber beams
Table ZZE3 – Material constant (ρc) – Seasoned timber columns
Table ZZE4 – Material constant (ρc) – Unseasoned timber columns
Table ZZF1 – Quantity symbols
Table ZZF2 – Modification factors for strength (k)
FIGURES
Figure ZZ4.1a – Configuration requirements – Load applied parallel to grain – Member in tension
Figure ZZ4.1b – Configuration requirements – Load applied parallel to grain – Member in compression
Figure ZZ4.2a – Configuration requirements – Load applied perpendicular to grain – End joint
Figure ZZ4.2b – Configuration requirements – Load applied perpendicular to grain – Internal
Figure ZZ4.3 – Minimum nail spacing in radiata pine sawn timber
Figure ZZ4.4 – Definition of connection, joint, and member
Figure ZZ4.5 – Example of the maximum distance perpendicular to grain when in-service shrinkage or swelling of timber is likely, unless consideration is given to limit shrinkage stresses
Figure ZZ4.6a – Configuration definitions – Load parallel to grain – Member in tension
Figure ZZ4.6b – Configuration definitions – Load parallel to grain – Member in compression
Figure ZZ4.7a – Configuration definitions – Load perpendicular to grain – End joint
Figure ZZ4.7b – Configuration definitions – Load perpendicular to grain – Internal joints
Figure ZZ4.8 – Nail diameters
Figure ZZ4.9a – Applicable thickness of members in nailed joints – Single shear
Figure ZZ4.9b – Applicable thickness of members in nailed joints – Single shear
Figure ZZ4.9c – Applicable thickness of members in nailed joints – Double shear
Figure ZZ4.10a – Minimum spacing of nails – No pre-boring
Figure ZZ4.10b – Minimum spacing of nails – No pre-boring – Sawn radiata pine only
Figure ZZ4.10c – Minimum spacing of nails – Pre-bored to 0.8D
Figure ZZ4.11 – Screw diameters
Figure ZZ4.12a – Applicable thickness of members in screwed joints – Single shear
Figure ZZ4.12b – Applicable thickness of members in screwed joints – Single shear
Figure ZZ4.12c – Applicable thickness of members in screwed joints – Double shear
Figure ZZ4.13 – Minimum screw spacing requirements
Figure ZZ4.14 – Example of rivet dimensions meeting the requirements of ZZ4A.5.4.1
Figure ZZ4.15a – Rivet joint thicknesses and penetration definitions – Member loaded on one surface
Figure ZZ4.15b – Rivet joint thicknesses and penetration definitions – Member loaded on two surfaces
Figure ZZ4.16 – Applicable thicknesses of members in bolt or dowel connection
Figure ZZ4.17 – Minimum bolt spacing requirements – Parallel to grain
Figure ZZ4.18 – Minimum bolt spacing requirements – Perpendicular to grain
Figure ZZ4.19a – Separation of side members in dowel joints
Figure ZZ4.19b – Separation of side members in dowel joints – One possible prevention measure
Figure ZZ4.20 – Applicable thickness of timber member for a coach screw laterally loaded
Figure ZZ4.21 – Minimum coach screw spacing requirements – Parallel to grain
Figure ZZ4.22 – Minimum coach screw spacing requirements – Perpendicular to grain
Figure ZZ4.23 – Load-deformation curve for fastener group and failure modes
Figure ZZ4.24 – Example of possible member brittle failures of all fastener groups in a joint
Figure ZZ4.25 – Example of possible brittle failures of all fastener groups
Figure ZZ4.26 – Loaded surface factor (KLS) values
Previous versions
NZS AS 1720.1:2022 (Excludes AS Text)
Online Library subscription information
Online library subscriptions provide a cost-effective solution for organisations of any size to access the latest standards, offering 24/7 access to a personalised catalogue. The service ensures subscribers have have the most up-to-date version of selected standards, incluing automatic updates for any amendments or versions. Pricing is dependent on the chosen standards and the number of concurrent users, with discounts applied from the standards PDF price. For customised subscriptions or further inquiries, contact the Online Library team.