TRA members offer a variety of services in addition to the design and supply of trussed rafters. When you choose a TRA member to install your trussed rafters, they will help with defining safe and effective systems of work to meet regulatory requirements.
Installation of trussed rafters is a specific construction skill that involves work at height and materials that are unstable during the initial stages so it should always be considered a high risk. The information below is intended to mitigate that risk by following the correct process for the safe handling, storage and installation of a trussed rafter roof.
Find out more about method statements
Site design and planning – collaboration between the contractor and manufacturer
Buying from a TRA member ensures you are dealing with reputable and highly experienced suppliers who can advise on the legal obligations and responsibilities of those involved in the roof construction process. These include:
- Typical roof designs, trussed rafter types and weight considerations
- CDM 2007 and Work at Height Regulations 2005 including Site Risk Assessment/Method Statements
- Roof construction methods for individual trusses, prefabricated truss units, full roof assembly on ground
- Temporary site works design and planning including temporary bracing, wind factors, point loading
- Site staff training/qualification for handling and installation of trussed rafters
- Site handling methods for crane, telehandler, forklift, manual team handling, safe routes/obstructions
- Delivery scheduling, vehicle type, size and routes for access, specific site restrictions or requirements
- Just-in-time deliveries direct from vehicle to roof installation
- Site storage methods for on ground, at height, temporary racking design and capacity, weight limits.
TRA members provide information on trussed rafter dimensions, weights, configuration and location within the layout and installation sequence. In addition, they will provide schedules or drawings to enable the contractor to define their requirements in terms of delivery schedule, maximum bundle weight or size and the requirement for sacrificial slings if scheduled for crane offload. Where appropriate, TRA members also provide the necessary fixing details to construct compound or multi-part structures.
Loading at truss manufacturer (Manufacturer’s responsibility with information from contractor)
The TRA provides its members with defined method statements to ensure the safe loading and transport of trussed rafters. These procedures include:
- Differentiated restraint banding to be used when loading: one colour to secure the bundle and a different colour for securing the bundles to the vehicle.
- The need for appropriate training of the manufacturer’s loading staff and delivery drivers.
Unloading at site (Contractor’s responsibility)
Contractors are responsible for the unloading of vehicles at site. The TRA assists its members with generic method statements for safe methods of unloading either by crane or other forms of mechanical handling equipment. These documents are available to customers from your trussed rafter supplier upon request. These procedures emphasise:
- All unloading must be undertaken from ground level with no need for anyone to access the lorry bed
- Delivery drivers are aware of their responsibilities and are able to provide information
- The need for suitably trained banksman, slingers and crane operators on site.
Transfer and storage within site (Contractor’s responsibility unless subcontracted to TRA member)
Multiple handling and site storage stages increase the risk of damage so, where practicable, trussed rafters should be unloaded directly from the vehicle to a specially designed storage rack or loading bay as close as possible to their end location and time, ready for use. Other considerations for the contractor are:
- Site handling method: crane, telehandler, forklift, loader crane, manual team handling
- Safe routes
- Site storage: location on ground, at height, flat, upright, racking design and capacity, weight limits and weather protection
- Stability and safety within storage, trained banksman, equipment operators.
Installation on site (Contractor’s responsibility unless subcontracted to TRA member)
- Trained installers fully informed of site temporary works procedures
- Access decking, access above head height, guarding, top hat installation
- Lifting plan, procedures and weight limits, temporary holding/storage area
- Trained banksman, slingers, crane operators plus adequate personnel resources
- Truss spacing and placement, fixing metal work such as truss clips, shoes and hangers
- Temporary bracing plan, design, strength/adequacy, material quality and size, fixing, method/type/number
- Permanent bracing plan/installation, sheathing/sarking boards membrane/felt/batten installation.
- Examples of good practice for trussed rafter installation
- TRA installation sequence
- Keepmoat example
- HSE document- HSG 33 Health and Safety in Roof Work
- TRA Technical Handbook – Issue 2 May 2007
- TRA Members Method Statements – Loading/Unloading
- BS 5975: 2008 + A1: 2011 – Code of practice for temporary works procedures and the permissible stress design of falsework.
- Home Builders Federation – Guidance on Manoeuvring of Roof Trusses – July 2012
- CSkills Awards Level 2 Diploma Site Carpentry
- Unit K/504/7882 Carry out structural carcassing operations
Handling, Storage & Installation Roadmap
Trussed Rafter – Handling, Storage & Installation Roadmap to download this information as a PDF file