The TRADA designs as stated earlier are no longer available, but the design principles are sound and all relevant metalwork and connectors are still available. Figure 5.3 is continued in this fourth edition by way of illustrating this typical bolt and connector truss but it must be emphasised that the illustration is not a current TRADA design.
Many homes built in the 1950s, 1960s and 1970s used this type of construction and it has proved to be a rugged durable roof structure. Similar roof trusses today would have to be engineered, but that done, purlins, common rafters and ceiling joists can all be 'designed' from building regulation span tables.
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