Pre-fabricated wood I-joists and structural composite lumber (SCL) products do not require an engineer’s seal on design calculations.
Since all building materials cannot possibly be covered in the code, the IRC permits using alternative materials including engineered wood products. As a manufacturer of engineered wood products, we rely on our code reports as evidence of acceptability as alternative materials (IRC R104.11). To help the building official verify the acceptability of alternate materials, the ICC Evaluation Service, Inc. (ICC ES), was established for the purpose of providing an independent and impartial review of alternate materials for compliance with the building codes. Our ICC-ES code reports provide clear evidence that products comply with codes and standards and are, therefore, “code accepted”. TJI® joists, Microllam®, Parallam® and TimberStrand® products are fixed property materials, as is solid sawn lumber. EWP is different from plated trusses which are custom built for each job and don’t have code reports.
Using the code reports as a basis, manufacturers frequently develop literature and software tools to aid in the specification and installation of the products. The manufacturer’s span/load tables for the material in question may be used to verify its structural acceptability in a given application. Literature by the manufacturer typically has span/load tables that show the load capacity of the member for various spans, in pounds per linear foot of the member. For more complex applications such as point load conditions, our software tools such as Forte® can be used for design.
When sealed documentation is requested for engineered wood products it is often due to a misapplication of the requirements for plated trusses. More information on the differing requirements can be found in TB-120, Engineer’s Seal Requirements for I-Joists, Structural Composite Lumber and Plated Trusses. Requesting seals when not required, adds unnecessary costs and delay to the project and is contrary to the intent of the residential code which is to allow prescriptive construction of a typical house without needing a design professional. In most cases, wood I-joists and structural composite lumber (SCL) products do not require an engineer’s seal on design calculations.
Weyerhaeuser does not act as the engineer of record for any project. The proper authority is to review any calculations and confirm they are consistent with the intent of the overall building design.
Using Weyerhaeuser Products in Conventional Code: Technical Resource Sheet 1502