For economical spacing of roof truss, if t, p, r are the cost of truss, purlin and roof coverings respectively, then

Explanation:

• The cost of the truss should be equal to twice the cost of purlins plus the cost of roof covering. t = 2p + r

• The total cost (t) depends on the costs of trusses, purlins, and roof covering.

• Roof covering cost usually dominates as it covers the entire roof area.

• Economical spacing balances these costs to minimize total cost.

 Additional Information

• A roof truss is a structural framework composed of straight members arranged in triangular units to support roof loads efficiently.

• Trusses transfer loads from the roof covering and purlins to the main supporting structure, such as walls or beams.

• The spacing of trusses affects the quantity and cost of purlins and roof covering required.

• Closer truss spacing means more trusses (higher truss cost) but fewer and shorter purlins and less roof covering overlap, while wider spacing reduces truss cost but increases purlin and roof covering costs.