Trussed Rafter Roofing
Roof construction in the UK took a new turn in the 1960’s away from the traditional carpenters cut system. This involved cutting every piece of timber by hand, to fit the plan, the overall strength of the roof being up to the builder’s opinion and carpenters experience.
This was relatively expensive owing the time taken, the amount of timber used, and the necessity of skilled joiners.
The use of trussed rafters became popular in the 1960’s following the development of truss connector plates. These are light gauge steel plates with holes punched through them forming teeth which are then pressed into the side of the timber by machine and nailed at the same time.
This made jointing strong, straight forward and in-line. Using these prefabricated manufactured sections gave the economical advantages of speed, and because of the ability to span from eaves to eaves, doing away the need for intermediate support walls.
Modern roofing for houses is now almost completely made with trussed rafter systems, almost totally out-pacing site carpentry with its strength graded high quality timber basics.
The time spent in factory manufacturing is not only time saved on the construction site, it also keeps the timbers in a stable, dry environment and away from the possible mistreatment some materials take on site such as accidental damage or over exposure to the weather. Additionally, the heavy construction equipment and machinery required to carry, lift and install modern preassembled roofing components is much more efficient that in the past.
They are much faster to erect, put into place by crane utilising relatively unskilled labour, and the entire frame of a house roof can be in place in a matter of hours.
The trussed rafter manufacturing industry has moved with the modern times and trends of house building using computer designing to allow roof scapes to be what in traditional method, would be considered complex or difficult.
The move toward providing character homes even in high density sites such as new-town expansion or brownfield sites requires the ability to be able to build variations within standard truss designs, and the adaptability of the trussed rafter system can economically and physically encompass a variety of characteristics.
Even with developments requiring “shoulder to shoulder” density building individuality can be applied, with hip-end roofs, valleys or L-shaped returns being easily integrated.
When the trussed rafter usage began to overtake all other methods of roof construction, it was noted that the system did not take kindly to alterations once in place. The intrinsic strength of the construction could be jeopardised by alterations as simple as a small dormer, which, in time could make the roof sag or worse.
Today’s computers are capable of letting designers create complex designs and inspect them in virtual 3D, the computer compensating for stresses and strengths at every turn. In this way multi-design roofing can always be provided safely and over- fulfil building regulation requirements.