R610.3.1

Section R610.3.1 is titled 'Lumber' and covers requirements for wall construction. The requirement for lumber used for structural insulated panels to be a minimum grade of a specific species, and the allowance for the substitution of lumber provided it meets or exceeds certain criteria of the prescribed lumber in this code section is established. The purpose of this section is to prevent structural failure.

The model shows a section of a piece of sawn lumber with a grade mark stamped onto it.