Assessment of structural adequacy of monoslope/skillion canopy, with roof pitch no greater than 5 degrees. The structure comprises of no more than 4 different beams. (eg. back channel, fascia beam, rafter, cladding rail).
The structural elements to be arranged on a uniform rectangular grid, the overall plan being a simple rectangle. No clear span to exceed 6m.
NB: Whilst elsewhere on this website it has been indicated that design effort is proportional to complexity not size, it is to be noted that beyond a certain size the structural form changes, and in so doing so does the complexity. If sheet metal is used then the maximum length of cold-formed section which can be folded on a brake press is typically 3m, whilst roll-forming allows lengths upto 12m. If timber is used then the maximum length of sticks available is typically around 6m, with longer lengths available in glulams and LVL’s. Whilst members up to 12m long can be transported, members 6m long are more convenient for transporting around suburban streets. Two 6m sticks can produce a gable roof with a span less than 12m. Monoslope roofs with large clear spans tend to be sensitive to deflection, requiring heavier sections than a gable roof of the same span would require. Natural camber in the structural sections is also more visible in long spans. So whilst the basic structural form can remain unchanged up to the member lengths exceeding 12m, it is also the case that lengths less than 12m introduce additional detailing issues. It is possible for a 3m wide canopy to be more complex than a 12m wide canopy, or vice versa. So to provide some flexibility in the structural form, but limit the complexity introduced with variation in size, some cut-off size needs to be adopted. At present that cut-off size is 6m. In the future with more variety of structural forms explicitly described the cut-off dimensions will increase.
The assessment does not include the assessment of the attachment to a house or other building.