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Roof Trusses or Trussed rafters are now specified for the majority of domestic roofs and a significant proportion of commercial buildings constructed in the UK. The trussed rafter is an individually designed component, engineered to provide a structural frame for the support of a roof or similar structures.
Pre-fabricated from high quality, stress graded timbers and joined with steel nail-plate fasteners, the trussed rafter offers:
- A flexible, practical and fully engineered solution to your roofing requirements.
- Economy of materials, as trussed rafters can use up to 40% less timber than a traditionally formed roof.
- Reduced labour costs on site, due to the amount of prefabrication, releasing site joiners for more complex areas.
- Quick erection of the roof structure, enabling other trades to commence quickly.
- Reduction in site waste, loss and pilferage of valuable materials.
- Space saving on site, with no need for timber storage or carpentry work areas.
Manufacture
Perran Trusses have invested in a brand new manufacturing facility that includes the latest Table press and auto stacking system to enable the finished roof truss to be manufactured quicker but also to ensure outstanding accuracy and improved cost savings, this in addition to the Hundegger timber processing station allows our trusses to be designed and sent to site precut loose timber (Angles/bevels/birds mouth cuts, seat cuts etc) to enable quicker installation.
Design
Perran trusses design Roof Trusses in accordance with the current Code of Practice, which is BS 5268: Part 3, and the relevant Building Regulations, with the use of the world leading software MiTek.
Spans
Standard roof trusses supplied by Perran Trusses can be designed/manufactured and delivered up to 11 metres in 35mm timber, and 16 metres in 47mm timber. Spans in excess of these can be designed but are often supplied as multiple trusses and then fixed together on site.
Pitches
It is more economical to standardise the range of pitches between 15 & 40 degrees, however, trusses may be supplied outside this range. Care should be taken when specifying because deflection problems may arise with e.g. Very shallow pitches.
Preservation
All timber used in the manufacture of Roof trusses by Perran Truss may be supplied either untreated or treated , the treatment used is the new double vacuum water based preservative fluids, which ensures a high level of treatment throughout the timber section.
Design Responsibility
Certain information is required by us so that we can produce accurate and economical designs to your exact requirements. All you need to do is to send us the drawings of a scheme. These may be sent as a DXF, if this is not possible, your sketches or advanced drawings should contain dimensions, and show elevations, floor plans, sections etc. Site plans are also helpful to show any relationship between the different building designs.
The 2 options available regarding levels of responsibility are shown and broken down below
Trussed rafter designer
Responsible for the individual trussed rafter components only.
We will require Span over wall plates , Pitches or rise of Roof Truss, type of Truss, Type and size of overhang, Positions of Load bearing supports, Type/weight of Roof covering, Water tank size and position, any unusual wind/snow conditions, Positions of openings in roof/ceilings (Chimneys, dormers ceiling hatches etc)
Roof designer
Responsible for the complete roof structure as a whole.(An additional fee may be payable for this service), Type of ceiling to be used, Wind loads from walls to be taken into the roof structure, Additional loading from M&E plant within the roof space, Relevant sections of the site Health and Safety file, Is a site visit required ?, Is a collateral warranty required ?
Before making a final decision on what type of truss you would like please contact one of our Design team to ensure that the truss will be suitable for your requirements.
