Canary Wharf is a major business district in east London, within the London Borough of Tower Hamlets. It is one of the United Kingdom's two main financial centres â along with the City of London â and contains many of Europe's tallest buildings, including the second-tallest in the UK, One Canada Square.[1][2]
Trusses and rafters are both assembled ahead of being installed onto the roof. Trusses are assembled in a factory using pre-engineered structures and joints. On the other hand, rafters are assembled at the construction site. As trusses are assembled in a factory, a lot of time can be saved.
The typical roof structure now consists of steel I beam rafters placed approximately 10 feet (this varies depending on purlin size and other variables) apart with either 4, 6, or 8 lightweight steel purlins installed horizontally across the rafters.n the past, the majority of roof structures were of wooden construction but over the past 15 to 20 years there has been a vast shift away from wood to metal (mainly steel) roof construction.