Wood Truss Design Drawing Requirements

Wood truss design drawings are required to be provided at the time of a permit to the Building Commission and approved prior to installation.  

  • Wood trusses are required to be designed in accordance with accepted engineering practice and certified by a Indiana registered Design Professional. 
  • The design and manufacture of metal plate connected wood trusses should comply with ANSI/TPI 1. 
  • Wood trusses are required to be braced to prevent rotation and provide lateral stability in accordance with the requirements specified in the construction documents for the building and on the individual truss design drawings. 
    • In the absence of specific bracing requirements, trusses should be braced in accordance with TPI/HIB.
  • Truss members should not be cut, notched, drilled, spliced or otherwise altered in any way without the approval of the Indiana registered Design Professional.  
  • Alterations resulting in the addition of load (e.g., HVAC equipment, water heater) that exceeds the design load for the truss is not permitted without verification that the truss is capable of supporting such additional loading.

 

Wood Truss Design Drawing Requirements 

1. Slope or depth, span and spacing.

2. Location of all joints.

3. Required bearing widths.

4. Design loads as applicable.

     4.1. Top chord live load (including snow loads).

     4.2. Top chord dead load.

     4.3. Bottom chord live load.

     4.4. Bottom chord dead load.

     4.5. Concentrated loads and their points of application.

     4.6. Controlling wind and earthquake loads.

5. Adjustments to lumber and joint connector design values for conditions of use.

6. Each reaction force and direction.

7. Joint connector type and description (e.g., size, thickness or gauge) and the dimensioned location of each joint connector except where symmetrically located relative to the joint interface.

8. Lumber size, species and grade for each member.

9. Connection requirements for:

     9.1. Truss to truss girder.

     9.2. Truss ply to ply.

     9.3. Field splices.

10. Calculated deflection ratio and/or maximum description for live and total load.

11. Maximum axial compression forces in the truss members to enable the building designer to design the size, connections and anchorage of the permanent continuous lateral bracing. Forces shall be shown on the truss design drawing or on supplemental documents.

12. Required permanent truss member bracing location.