Bradfords have been supplying roof trusses to the building trade throughout the Southwest for generations. Contact us today for a detailed quote tailored to the specific requirements of your project.
What Are Roof Trusses?
Roof trusses are important structural components used in the construction of roofs for buildings. They are designed to support the weight of the roof covering, any windows or skylights, and must be able to cope with additional loads, such as snow. Although roof trusses can be built from metal or hardwood, such as oak, it is far more common for them to be made from construction timber. They are pre-fabricated and delivered to the site ready to be installed. Delivery often requires a very large vehicle equipped with a crane. For this reason, it is important that the installation site has good access.
What are the main types of roof trusses?
35mm Standard Roof Trusses.
The most common type of roof truss is a 35mm standard truss. These are used in most modern new build houses and are suitable for outbuildings, garages, extensions and annexes. Although they are cost effective and relatively simple to install, it is worth noting that they do not offer the option to extend the property into the roof space at a later date since the roof space itself contains two diagonal supports. They do offer some additional loft space and the loft can still be insulated and boarded if required. However, if a larger loft space is required, there are better trusses available.
Attic Roof Trusses
Attic Roof Trusses offer more open space in the roof area than standard trusses, making them ideal for habitable loft conversions or simply to make more storage space available. Typically, attic roof trusses feature an overhang at the eaves of the roof, though they can be manufactured without this to achieve a different aesthetic. Because attic roof trusses have fewer supporting timbers, they are typically made from larger timber sections allowing them to achieve the required load capacities.
Mono Roof Trusses
Mono Roof Trusses slope in only one direction and can be thought of as half of a standard truss. They are commonly used in porches and lean-to extensions where the roof terminates against an existing wall. Such structures rarely require habitable space within the roof itself and therefore, Mono Roof Trusses typically utilise the same construction as standard trusses.
Is it cheaper to use Roof Trusses or Rafters?
It’s generally cheaper to use roof trusses than rafters primarily because they are delivered to the site prefabricated so they require less labour to install. Whilst every project is different, it is possible to save a considerable amount of money by using trusses instead of rafters. It is important to consider the potential cost of delivering such large structures over long distances and the site access requirements to get them to the right place. For this reason, it’s a good idea to choose a supplier of roof trusses near you who can provide an expert delivery service.
How many roof trusses will I need?
The total number of roof trusses you need will depend on the specifications of your project and should be calculated by a professional, usually a structural engineer or an architect. However, it is generally the case that trusses should be set at 600mm centres. That means you can work out the number of trusses you may need using this formula:
Trusses Required = (roof length in mm / 600) +1
So, for example, a roof of 6 metres (6,000mm) will require 11 trusses if they are to be spaced at 600mm centres.
The same calculation can be made using imperial units as follows:
Trusses Required = ((roof length in feet * 12) / 24) +1
A roof of 20 feet will require 11 trusses set at 24-inch (2 feet) centres
It is, however, essential that you check your own requirements with a qualified professional.
What is the difference between a roof truss and an attic truss?
As shown in the illustration above, attic trusses use vertical and horizontal supports to spread the load across the span rather than diagonally orientated supports. This means they allow much more space within the roof space itself, often enough for the roof to be converted into storage or habitable space. It is important to note that any habitable space will need to adhere to certain building regulations governing such things as insulation levels. Always check with your architect or local planning authority before undertaking any conversion works.