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Mitek Guidefor ROOF Trussinstallation

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Mitek Guidefor ROOF Trussinstallation TIMBER ROOF TRUSSES MiTek GUIDE for ROOF TRUSS Installation The Timber Roof Trusses you are about to install have been manufactured to engineering standards. To ensure that the trusses perform, it is essential that they be handled, erected and braced correctly. 2019 - Issue 1 mitek.com.au TABLE OF CONTENTS Fixing & Bracing Guidelines For Timber Roof Trusses General .....................................................................................................................................................................................3 Design ......................................................................................................................................................................................3 Transport..................................................................................................................................................................................3 Job Storage ..............................................................................................................................................................................3 Roof Layout .............................................................................................................................................................................4 Erection and Fixing ...................................................................................................................................................................4 Girder and Dutch Hip Girder Trusses .......................................................................................................................................7 Saddle Truss Fixing ................................................................................................................................................................11 Roofing Battens .....................................................................................................................................................................12 Permanent Bracing ................................................................................................................................................................12 Web Ties and Stiffeners .........................................................................................................................................................17 Girder Brackets ......................................................................................................................................................................20 Guard Rail Systems ...............................................................................................................................................................26 MiTek 20/20 User Guide .........................................................................................................................................................28 Truss Installation Checklist ....................................................................................................................................................32 Product Certification ..............................................................................................................................................................32 ILLUSTRATIONS All technical illustrations in this Guide have been converted to pdf, AutoCAD 2000 dwg & dxf file formats. They are also compatible for use with MiTek SAPPHIRE™ - making them the ideal, easy reference for installation instructions and data. To access these illustrations, please visit: mitek.com.au GENERAL JOB STORAGE AND LIFTING The roof trusses you are about to install have been manufactured to Trusses should be inspected on arrival at site. Any damaged trusses engineering standards. To ensure that the trusses perform as designed should be reported immediately and not site repaired without approval of it is essential that they be handled, erected and braced correctly. the truss fabricator. The installation of prefabricated timber trusses is covered by the Australian Where it is anticipated that trusses will be stored on site for an extended Standard AS 4440 “Installation of NailPlated Timber Trusses”. The following period of time before use, adequate provision should be made to protect information is an abbreviated set of instructions designed to assist trusses against the effects of weather. with on site work and is not intended to replace the need to reference Once trusses are installed they should not be left exposed to weather for long AS 4440. The following recommendations apply to roof trusses on standard periods. Repeated wetting and drying has a detrimental effect on the strength domestic buildings where truss design details are obtained from MiTek of both timber and connection. engineering programs. Details for commercial, industrial and non standard Protective covering, where used, should allow free air circulation around trusses. domestic buildings, are to be provided by an Engineer responsible for the overall building design. Trusses when stored on the job site should be on timber fillets clear off the ground and in a flat position to avoid distortion. DESIGN When lifting, care must be taken to avoid damaging of joints and timber. 1. Trusses are designed for normal roof, ceiling and wind loads to suit specific Spreader bars with attachment to the panel points should be used where jobs and conditions. Additional loading such as Solar Units, Hot Water span exceeds 9000 mm. Never lift by the apex joint only. Tanks, Air Conditioning, etc. require special consideration. Advice should The trusses may also be placed on the top plates by pulling them up on skids, be sought from the truss fabricator prior to commencing construction. spread at 3000 mm, taking the same precaution as described above. 2. Wall frames and beams supporting trusses must be designed for the correct Ensure that the trusses are not distorted or allowed to sag between supports. roof loads. Refer AS 1684 “Residential Timber-Framed Construction” The recommended method of lifting trusses will depend on a number of factors, for details. including truss length and shape. 3. Wind load is an important factor in the design and performance of roof In general, sling truss from top chord panel points as shown below. trusses. Ensure that you have correctly advised the truss fabricator with Slings should be located at equal distance from truss centreline and be regard to wind load requirements and that adequate provision has been approximately 1/3 to 1/2 truss length apart. made to fix trusses to the support structure to withstand wind uplift forces. The angle between sling legs should be 60° or less and where truss spans 4. Trusses are generally designed to be supported on the outer wall with inner are greater than 9000 mm a spreader bar or StrongBack should be used. walls being non load bearing. Where it is necessary to use internal walls Some typical examples are shown below. for load bearing, these will be clearly shown on layouts. Note that the supporting structure is stable in its own right. 5. Before ordering trusses, ensure that your particular requirements have been provided for and that all relevant information has been supplied to 60° or less the truss manufacturer. If non standard trusses are being used, ensure that erection and bracing details are known before erection commences. RT001-a 6. For environments where the atmosphere may be conducive to corrosion, such as some types of industrial and agricultural buildings, or buildings near the ocean and subject to salt spray, consideration should be given to the use of G8S stainless steel connector plates. Approx 1/2 to 1/3 Important Note of truss length 1. It is the Builder’s responsibility to ensure that all relevant information required for design is provided to the fabricator at time of ordering trusses, including spans, pitches, profiles, quantities and loadings. Final confirmation of details by the fabricator with the builder is recommended prior to manufacture. RT001-b 2. Trusses are designed to be part of a structural system, which includes battens/purlins, bracing, binders, fascias and the connection of these components. The full strength of trusses is not achieved until all components are installed correctly. All trusses must braced (temporary and permanently) and stabilised throughout installation of the roof truss system. No truss should be loaded until all permanent bracing is fixed and battens/purlins are installed. Installers should not stand on any truss until all temporary bracing is fixed in place and the truss is stabilised in RT001-c accordance with the following instructions. 3. A risk assessment shall be undertaken for each site taking into account Spreader bar all relevant workplace safety practices, including working height. It is the builders responsibility to consider the site conditions when determining procedures for handling, lifting, fixing and bracing of roof components. The procedures shall be discussed with all employees and sub contractors working on site and the agreed methods documented. A useful template RT001-d for this purpose is the “Safe Working Method Statement No. 10” which is published by the Housing Industry Association (HIA) and available on Approx 1/2 to 1/3 their website. “The National Code of Practice for the Prevention of Falls in of truss length Housing Construction” produced by Safe Work Australia contains specific Spreader bar information and guidance on risk management for working at height in
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