Max Span Calculator

Instructions:

1. Select a grade.
2. Choose one or more species/species grouping(s). If desired, filter the species list by selecting NA for North American species only or non-NA for non-North American species only. The default ALL is a combined list of both NA and non-NA species.
3. Select one or more region(s)/country(ies).
4. When satisfied with the information included on the Stamp, click “Add Stamp”.
5. Repeat until desired number of Stamps have been added.
6. Enter lumber size, type of use, and span requirements in the Design Criteria section.

Calculator generates the maximum span distance as well as the bending strength (F_b), shear strength (F_v) and bearing strength (F_cp) values for each Stamp selected.

Note: The design values shown in the table are applicable to lumber surfaced either unseasoned (S-GRN) or dry (S-DRY or KD). In calculating the design values, the change in strength and stiffness that occurs as lumber dries has been taken into consideration as well as the reducing in size that occurs when unseasoned lumber shrinks. The design values have been factored with adjustment factors in accordance with paragraph 200 a-l in WCLB Standard No. 18 and/or the National Design Specification (NDS) Supplement published by the American Wood Council.