How Do You Design Roof Trusses?

How Do You Design Roof Trusses?

How Do You Design Roof Trusses?

The following are quick steps of the truss design process;

Step 1: Create a model of the walls, roofs, ceilings, floors, and major beams.

Other items in the building model support trusses and the environment must be finished before adding trusses.

All of the items do not function as bearing components. With various limitations, walls, beams, roofs, ceilings, and floors can serve as bearing components.

Step 2: Create trusses and truss regions.

Truss regions are created by items that limit the truss volume.


Limiting items’ height positions, particularly a hip slope should fit snugly against an end wall.

Truss connections, jack trusses perpendicular to the girder. The truss should meet the girder.

Step 3: Create the truss members.

Truss members are formed according to user-defined criteria.


– Examine the member specifications and truss type.

– In engineering, check member material and selected grade is employed.

Step 4: Examine the connections between members.

Connections between truss members must be defined. Truss member framing is the process of connecting members, although the user must review manually placed members.


– Check the fastener kinds and codes used; connection capacity is determined by fastener type and code.

– Trimming connections can be utilized exclusively between truss members, but the connection is not designed.

– If the software is set to force a web connection at the bearing site, the saddle truss verticals should be in line with the top chord below, or at least the middle of the red fastener pattern macro in connection should be between the top chord faces below.

– To build a supportive relationship between the girder truss and trusses supported by the girder, use joist hangers or direct screw connections between trusses.

Step 5: Examine the supports.

Physical touch or connection between the supported and supporting items is required. The user must link trusses that are supported by other trusses.


– Check the truss-to-truss connections and make any necessary changes.

– Check bearing wall heights and truss member contacts.

– Examine the bearing main beam locations and truss member connections.

– Hip drop truss/girder sloping top chords should not reach inside hip rafters since this results in a poor support relationship during engineering.

Step 6: Create truss labels and drawings

Truss drawing is used to produce truss and truss member labeling. Before beginning Truss Design, a truss drawing must be prepared and updated. Labels are used to describe engineering outcomes.


– Prior to Truss Design, create truss drawings.

– If the truss geometry changes, update the truss drawings.

Step 7: Calculate the internal pressure zone.

Internal pressure area is the space within a structure constrained by its outside walls and internal ceiling or roof. If the ceiling is permeable, the roof limits the internal pressure area.


-Check the closed polyline for internal pressure regions and alter the polyline if necessary.

Step 8: Calculate wind loads for the ceilings and roofs.

Wind loads are created in accordance with the chosen building code.


– During input, choose the main wind direction depending on the geometry of the building site and environmental factors.

– Check Design Criteria defaults, particularly building placement in relation to terrain topography.

– Check the definitions of the exposure and enclosure criteria in the building code.

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