TL;DR (generated, confidence: high)

BCG 13-10 allows non-fire-retardant-treated wood framing in exterior walls of Type III construction R-2 occupancy buildings as an alternative to fire-retardant-treated wood, provided specified conditions are met.

Key points:

Oregon Structural Specialty Code permits fire-retardant-treated wood in Type III-A or III-B exterior walls with 2-hour fire-resistance rating or less (Building Code Guide 13-10: Type III Code Guide ↗)
Portland Permitting & Development allows non-fire-retardant-treated wood in R-2 occupancy Type III buildings without building code appeal if all conditions are met (Building Code Guide 13-10: Type III Code Guide ↗)
Sacrificial stud: 2-inch minimum nominal thickness extra stud against structural framing to provide fire resistance at exterior wall openings (Building Code Guide 13-10: Type III Code Guide ↗)
Continuous and solid: without air breaks or interruptions by lesser fire-rated materials, may be built from multiple wood members meeting structural requirements (Building Code Guide 13-10: Type III Code Guide ↗)
Approved wall assembly: designated wall assemblies in guide graphic details, constructed as described unless a tested assembly (Building Code Guide 13-10: Type III Code Guide ↗)
Tested assembly: fire-resistant rated assembly tested per Oregon Structural Specialty Code (Building Code Guide 13-10: Type III Code Guide ↗)

Building Code Guide 13-10: Type III Code Guide

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Source: Building Code Guide 13-10: Type III Code Guide ↗ Last modified: Sun, 19 Apr 2026 20:06:26 GMT

Building Code Guides (BCGs) provide a comprehensive alternative to a complicated set of code requirements.

BCG 13-10: Type III Code Guide

QUESTION: In buildings of either Type III-A or III-B construction, the Oregon Structural Specialty Code (OSSC) permits fire-retardant-treated wood framing within exterior walls where the wall is 2-hour fire- resistance-rated or less.

May non-fire-retardant-treated wood be used as an alternative to fire-retardant-treated wood in these assemblies?

This question includes the condition in which the Special Provisions of OSSC Chapter 5 are utilized for a four or five-story, Type III building above a Type I-A podium building.

RESPONSE: Yes, instead of using fire-retardant-treated wood framing, Portland Permitting & Development (PP&D) will allow non-fire-retardant-treated wood framing within exterior walls of R-2 occupancy buildings of Type III construction without a building code appeal provided all of the conditions listed below are met.

DEFINITIONS AND TERMINOLOGY

Approved wall assembly: Wall assemblies designated “approved wall assembly” in the graphic details of this Guide must be constructed as described in the Conditions (below), unless it is a tested assembly.

Continuous and solid: The terms “continuous” and “solid” used in the details of this Guide means without air breaks or interruptions by a material of lesser fire rating for the full length and depth of the condition. A “continuous” or “solid” member may be built up of multiple wood members provided it complies with all structural requirements.

Sacrificial stud: The term “sacrificial stud” used in the graphic details of this Guide means an extra stud, 2-inch minimum nominal thickness and the same depth as the adjacent framing member, installed against a structural framing member to provide additional fire resistance at an opening in an exterior wall.

Tested assembly: A fire-resistant rated assembly that has been tested in accordance with the OSSC.