The grade stamp on the 2x10s says SPF, No.2, S-DRY, with a mill number and an agency logo.

Grade Stamp Breakdown:

• SPF: Species group (Spruce-Pine-Fir). Inspector verifies it's appropriate for the application and meets structural requirements.
• No. 2: Grade. Indicates strength and appearance; No. 2 is common for structural framing. Inspector confirms it meets load-bearing specs per IRC Table 400.5.
• S-DRY: Surfaced-dry. Lumber dried to ≤19% moisture content. Inspector checks compliance with storage/drying requirements (IRC Section R2306).
• Mill Number: Identifies the manufacturing mill. Allows traceability for quality issues or recalls.
• Agency Logo: Third-party inspection agency (e.g., APA, WJ). Confirms independent verification of code compliance.

Why Inspector Cares:

• Ensures lumber meets structural grade and species requirements for load-bearing applications.
• Verifies proper drying to prevent shrinkage, warping, or moisture-related issues.
• Confirms third-party certification for code compliance.
• Enables traceability if defects or non-compliance arise.

Without these stamps, the inspector may reject the material for not meeting IRC Section R2306 requirements.

SPF = Spruce-Pine-Fir species group. Determines allowable design values (bending, shear, compression). No.2 = Visual grade. No.2 permits larger knots, slope of grain, and wane than Select Structural or No.1, so its design values are lower. S-DRY = Surfaced dry (≤19 % MC at mill). Means the lumber was kiln-dried after planing; it will not shrink significantly in service. Mill number = Traceability to the producing mill for quality audits. Agency logo (e.g., NLGA, WCLIB, SPIB) = Accredited grading agency that certified the grade stamp under ALSC PS 20.

Why the inspector cares IRC R502.1 / IBC 2303.1.1 require lumber to bear a grade stamp from an approved agency showing species, grade, moisture condition, and mill ID. The inspector verifies:

1. The stamp matches the species/grade assumed in the plans or prescriptive tables (e.g., Table R502.3.1 for floor joists).
2. Moisture condition suits the application (S-DRY or KD19 for interior framing).
3. No counterfeit or altered stamps.

If you substitute SPF No.2 for a design calling for DF-Larch No.1, spans must be reduced per the span tables. No stamp = no approval.