BS 5268-3:1998
Superseded
A superseded Standard is one, which is fully replaced by another Standard, which is a new edition of the same Standard.
Structural use of timber Code of practice for trussed rafter roofs
Hardcopy , PDF
30-06-2006
English
15-08-1998
Committees responsible
Foreword
Introduction
1 Scope
2 Normative references
3 Terms, definitions and symbols
4 Assessment of structural adequacy
5 Materials
5.1 Timber
5.2 Plywood
5.3 Fasteners
5.4 Adhesives
5.5 Preservative treatment
6 Trussed rafter design
6.1 General
6.2 Limitations
6.3 Permissible stresses, fastener loads and nail
spacing
6.4 Loads
6.5 Method of design
7 Roof design
7.1 Design responsibilities
7.2 Overall stability
7.3 Wall plates
7.4 Plasterboard ceilings
7.5 Water tanks
7.6 Hatch, chimney and other openings
7.7 Roof environment
8 Fabrication
8.1 General
8.2 Assembly
8.3 Marking
9 Handling, storage and erection
9.1 Handling and transportation
9.2 Storage
9.3 Erection
9.4 Modification and repairs
10 Load testing
10.1 General
10.2 Testing authority
10.3 Information required by the testing authority
10.4 Quality and fabrication of trussed rafters for
test
10.5 Tests on similar configurations
10.6 Acceptance
10.7 Use of tested trussed rafters
11 Exchange of information
11.1 Information required by the trussed rafter
designer
from the building designer
11.2 Information to be provided by the trussed rafter
designer to the building designer
Annex A (normative) - Standard roof bracing
Annex B (normative) - Permissible spans
Bibliography
Figures
1 Alternative trussed rafter models for structural
analysis
2 Examples of joints
3 Wall plate location for simplified analysis
4 Shear stress condition at joints
5 Tension stress condition perpendicular to grain at
joints
6 Truss deflection components
7 Supports for water tanks
8 Spacing of trussed rafters to accommodate openings
9 Chimney opening
10 Hatch opening
11 Trusses rafter specification
A.1 Standard bracing for rafter and web members of
duopitch trussed rafters
A.2 Standard bracing for rafter and web members of
monopitch trussed rafters
A.3 Limiting spans for standard bracing of trussed
rafter roofs
A.4 Basic wind zones
A.5 Procedure for determining bracing design requirements
B.1 Truncated Fink trussed rafters
Tables
1 Species of timber
2 Modification factors for finger joint efficiency ranges
3 Maximum bay length of chord members
4 Maximum length of internal members
5 Minimum nail spacing for metal to timber joints
6 Summary of rafter loads
7 Summary of ceiling tie loads
8 Example load combinations
9 Bending moment coefficients (Km)
10 Load-sharing factors for principle trussed rafters
11 Force modification factor (Ke) for joints in
eccentrically loaded components subject to tension
perpendicular to grain
12 Modification factor (Kt) for strength tests on trussed
rafters
A.1 Thickness and fixing of sarking materials
B.1 Maximum permissible spans for rafter members shown
in Figure 11
B.2 Maximum permissible spans for ceiling ties shown in
Figure 11
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