Sealed Placement Plans
Question:
Is it the responsibility of the truss manufacturer to provide a sealed layout drawing for roof trusses?
Answer:
No. It is not the truss manufacturer's responsibility to supply a sealed layout or placement plan. A placement plan is simply a map showing how to lay out the trusses. It contains no structural or engineering information. From an engineering viewpoint, nothing on it has been engineered and, therefore, nothing requires a seal. IBC 2012/2015 2303.4.2 contains explicit language on what a truss placement diagram should include and specifies that these diagrams need not be sealed.
Placement plans are drawings that identify the assumed location of each truss based on the truss manufacturer's interpretation of the construction design documents. These drawings do not require engineering expertise. They are also not intended to replace, but rather to supplement and clarify, the framing layout contained in the construction design documents. Placement plans should be used by the contractor on the job only as a guide in locating each individual truss.
Most state laws assert that the work of engineering requires engineering education, training and experience in the application of the mathematical, physical and engineering sciences. The creation of a placement plan does not fit this definition of engineering and as such cannot be considered part of the practice of engineering as defined by most state practice-of-engineering laws. Since the plan is not an engineering document, a seal is unnecessary. A seal on a placement plan only indicates that the engineer has reviewed how each truss is to be placed and spaced, which does not require any engineering expertise. Any other interpretation of a seal on a placement plan would require an engineer to take responsibility for someone else's work, which is a clear violation of all state engineering laws.
Mistakenly, some local jurisdictions require sealed placement plans prior to the approval of the building permit. This requirement may be imposed, even if it is out of compliance with state law. In this instance, an engineer must, by law, explicitly define what his/her seal means, in terms of the scope of the work, when it is placed on the placement plan. Consider attaching the following sample notes, which describe an engineer’s scope of work, to any placement plans along with the seal of the engineer doing the work for the component manufacturer.
Scope of Work Note A: The truss designer's signature on this placement plan certifies that the individual truss designs are based on the truss positioning shown. The truss designer's seal on the attached truss design drawings indicates acceptance of professional engineering responsibility solely for the individual truss design drawings shown. The suitability and use of this component for any particular building is the responsibility of the building designer, per section 2 of the Truss Plate Institute's ANSI/TPI 1 as explained in section 3.0 of SBCA’s TTB – Standard Responsibilities in the Design and Application of Metal Plate Connected Wood Trusses. No building design or inspection is implied by the seals on the truss design drawings or truss placement plan. Verification that positions, dimensions and loads for each truss match the construction design documents and/or intent is the responsibility of the building designer. The truss designer is responsible for the correct application of the specified loading provided to him/her by the building designer and for the truss to truss connections. The truss designer is NOT responsible for:
- The transfer of lateral load from the roof to the shear walls.
- The connection of trusses to the bearing support.
- The design of the bearing supports.
- Temporary and permanent building bracing required in the roof and/or floor system.
- The transfer of vertical loads down to the foundation.
- The design of the foundation and soil.
- Analysis of the roof and/or floor diaphragms of the building.
- Connection of roof and/or floor diaphragm to the truss.
- Specifying loading used in the design of the trusses.
The building designer shall ascertain that the loads used on the truss design drawings meet or exceed the loading imposed by the building code.
Scope of Work Note B: THIS IS A TRUSS PLACEMENT PLAN ONLY. These trusses are designed as individual building components to be incorporated into the overall building design through the specification of the building designer. Please see the individual truss design drawings for each truss design identified on the truss placement plan. Please verify that all dimensions match the dimensions found on the job. The building designer is responsible for the permanent bracing of the roof and floor system and its integration into the bracing of the overall structure. The design of the truss support structure including headers, beams, walls and columns is the responsibility of the building designer.