Roof Truss Purlin Design

In timber construction purlins are nailed to the rafter or supporting trusses while in steel roof construction they are welded or bolted to the rafters or trusses by the means of cleats.

Roof truss purlin design.

Purlin plates are beams which support the mid span of rafters and are supported by posts. Sheathing to 7 to 9 ft with 2 in. The roof truss structure and design is integral to roof structural integrity and shape. This article and series of illustrated diagrams shows you all the parts of a basic roof truss king truss and queen truss.

Trusses can be constructed with smaller sized lumber than rafters and often their cost is not significantly higher than normal rafters. A purlin plate in wood construction is also called an arcade plate in european english under purlin and principal purlin. We provide angle iron steel trusses in gable lean to and header styles. As structural members they resist loads and provide lateral restraints for truss members therefore it is important to design them properly against forces.

In this case the truss loading is less so the cost of the trusses is less as well. By supporting the rafters they allow longer spans than the rafters alone. Finally the truss calculator will compute the best dimensional method to connect the pieces of the truss with steel joints and a bridge. Generally the following figures may be adopted.

Structural design i steel structures prof. Industrial buildings are low rise structures characterized by their low height lack of. Assessment of dead load live load and wind load design of purlin design of members of a truss detailing of typical joints and supports. These steel joints are needed to support the overall truss.

The same thing is true for the bridge of the truss. Sppu pune page 2 6b roof truss. The more complex the truss framework is the greater quantity of these joints will be required. The complete guide to roof trusses.

Purlins supporting slate roof 120 n m 2. Purlins supporting glazed roof 100 n m 2. Let s say you re planning to build a pole barn with only purlins and metal attached to the top of the truss while leaving the trusses exposed with no ceiling sheetrock. Purlins supporting corrugated sheeting 80 n m 2.

If roof sheathing material is to be applied directly to the trusses without auxiliary framing in order to save the labour of placing the purlins the spacing might vary from say 2 ft with 1 in. Design cost framing more. The size of purlins depends on the nature of roof covering supported wind and other loads and the spacing of the trusses. The term plate means a major horizontal supporting timber.

Pre welded purlin cups predrilled bolt holes and included mounting hardware for fast easy installation. Plank or to still greater dimensions with heavier plank. Steel trusses offer increased strength faster installation and a longer life compared to wood frame pole barn trusses.