Minimum Weight Design Of Long Span Roof Truss

If you can t get the heel height most residential trusses will have a 3 top cord.

Minimum weight design of long span roof truss.

Roofing paper inch plywood decking under tile roofing. If dead loads must be hung from trusses then extra support can be provided by installing support beams perpendicular to the trusses reducing the span of the bottom chords and increasing their ability to carry the weight load. Member of a truss. Calculate the height of a common truss using the building width and the slope of the roof.

The load span tables shown below demonstrate only a tiny subset of the possible combinations available with trussteel cfs roof trusses. Live loadany temporary applied load to a floor truss chord. Typically roof live load is snow while floor live loads are furniture. Finally the truss calculator will compute the best dimensional method to connect the pieces of the truss with steel joints and a bridge.

These steel joints are needed to support the overall truss. L d ratiothe ratio of the truss span l to its depth d both dimensions in inches. Trusses can be constructed with smaller sized lumber than rafters and often their cost is not significantly higher than normal rafters. Use of manufactured roof trusses can dramatically cut labor costs when framing a gable roof compared to building rafters.

Total designed load 25 pound per square foot 6 29 pound per square foot 2 35 pound per square foot 18. The same thing is true for the bridge of the truss. The span of the trusses their installed height above grade and or the acces sibility or availability of mechanical installation equipment such as a crane or forklift. The construction documents also provide the following information.

The installer should be knowledgeable about the truss design drawings truss placement plans and all notes and cautions thereon. A series of 30 ft 2 by 4 fink roof trusses spaced at 2 ft on center with 6 12 pitch are to be designed for use in a residence. Level returna lumber filler placed horizontally from the end of an overhang to the outside wall to form a soffit. 05425 cold formed steel trusses roof truss spans every trussteel roof truss is a custom design based upon the unique load span bearing use and code criteria of a particular project.

Depending on your roof slope add 4 to 5 inches for heel height. Compromised trusses can lead to severe structural problems such as bowing exterior walls sagging ridge lines and roof collapse.