General Guide

BC Building Code Part 3 vs Part 9

In British Columbia, the dividing line between Part 9 and Part 3 of the BC Building Code determines whether you legally require a Registered Architect, your municipal plan check timeline, and overall engineering costs. Here is the exact breakdown of the 600 m² footprint, 3-storey height limit, and major occupancy thresholds.

Quick Comparison: Part 9 vs. Part 3 Buildings in BC

Key structural, height, square footage, and professional sign-off differences between Part 9 housing and Part 3 complex buildings.

Feature	Part9	Part3	Significance
Building Height Limit	Maximum 3 storeys	Over 3 storeys (or high-rise)	4-storey+ buildings automatically trigger Part 3 fire protection rules.
Maximum Building Area	Up to 600 m² (approx. 6,458 sq ft) footprint	Exceeds 600 m² footprint (or high hazard)	Larger footprints trigger Part 3 complex building status.
Major Occupancies Covered	Residential (C), Small Business (D), Small Retail (E), Low-Hazard Industrial (F3)	Assembly (A), Care/Detention (B), High-Hazard Industrial (F1/F2), & Large C/D/E	Assembly uses like restaurants or daycares often push small spaces into Part 3.
Professional Design (AIBC Architect / Professional Engineer)	Qualified building designer or drafting firm (Part 9 scope falls outside mandatory architect reservation under the Architects Regulation)	Registered Architect (AIBC) and/or Professional Engineers where statutorily mandated by height, area, or occupancy	Standard Part 9 scopes generally do not mandate registered architectural retainers, streamlining design and permitting timelines.

Scope checklist

Building Permit Drawing Specialists

Does this project fit a Part 9 permit drawing package?

Use the height, area, and occupancy lines in the table above as a scope checklist. This is the Part 9 pattern Canadian Blueprint prepares Design & Drafting for:

Height: 3 storeys or less.
Building area: 600 m² footprint (approx. 6,458 sq ft) or less.
Occupancy: Residential (Group C), or a small office, shop, or low-hazard workshop (Groups D, E, and F2/F3).

Canadian Blueprint prepares municipal-ready permit drawing packages for Part 9 residential work and small commercial tenant improvements. Where the municipality requires it, those sets are coordinated with registered professionals such as a structural engineer. The city confirms the code path at intake.

Project Roadmap & Scope of Work

Select a phase below to jump to the details

1
The Core Thresholds (Area, Height & Use)
2
Townhomes vs. Condos
3
Mandatory Architect Rules
4
Pre-Permit Verification Checklist

Overview & Context

Overview

Whenever a client contacts Canadian Blueprint to design a new build, secondary suite, or commercial renovation, one of the first technical checks we run is determining whether the structure falls under Part 9 or Part 3 of the BC Building Code (BCBC).

This distinction is crucial because it governs: 1. Who can draw and stamp your plans (Part 9 Building Designer vs. Registered Architect & Professional Engineers). 2. How long municipal plan checks take (Part 9 residential sets stream through faster). 3. Construction costs & fire protection requirements (sprinkler systems, fire separations, standpipes, and exit stairs).

Step 1: The Core Thresholds (Area, Height & Use)

Phase 01

Under the BC Building Code, the baseline rule separating Part 9 and Part 3 comes down to three physical criteria: Building Height, Footprint Area, and Occupancy Type.

Part 9: Housing and Small Buildings

A building qualifies under Part 9 if it satisfies ALL of the following:
Height: 3 storeys or less in building height.
Building Area (Footprint): 600 square metres (approx. 6,458 sq ft) or less.
Occupancy Types Allowed:
Group C (Residential: single-family homes, duplexes, triplexes, townhomes, secondary suites).
Group D (Business & Personal Services: offices, beauty salons, small clinics).
Group E (Mercantile / Retail: small shops, retail stores).
Group F, Division 2 & 3 (Medium & Low-Hazard Industrial: small workshops, storage garages).

Part 9 residential wall assembly cross-section diagram — **Part 9 Residential Envelope:** 3D building cross-section detailing 2×6 wood framing, continuous exterior insulation, rainscreen strapping, and Step Code energy compliance.

Part 3: Fire Protection, Occupant Safety & Accessibility (Complex Buildings)

A building is classified under Part 3 if it meets ANY of the following conditions:
Height: Exceeds 3 storeys (e.g., 4-storey wood-frame apartments or high-rises).
Building Area: Exceeds 600 m² (6,458 sq ft) in building footprint.
Special Occupancy Types: Automatically includes Group A (Assembly: theatres, large restaurants, churches, arenas), Group B (Care/Treatment: hospitals, nursing homes), or Group F1 (High-Hazard Industrial).

Step 2: Townhomes vs. Condominiums

Phase 02

Homeowners and real estate investors often ask why renovating a townhome is different than renovating a condo unit, even if both are residential dwellings:

Townhomes (Typically Part 9)

Most standard 2 to 3-storey townhome developments in BC are constructed under Part 9.
Individual units are separated vertically by fire-rated demising party walls that extend from the foundation to the underside of the roof deck.
Permit Advantage: Renovating or altering non-structural interior layout elements in a Part 9 townhome can typically be handled under Part 9 building design provisions without triggering statutory architect or CRP requirements.

Condominiums & Apartment Buildings (Part 3)

Condos situated in 4-storey+ wood-frame complexes, mid-rises, or concrete high-rises are classified under Part 3.
Units are separated both vertically and horizontally by floor-ceiling assemblies and demising walls designed to strict acoustic and fire resistance ratings.
The Catch: Altering walls, plumbing stacks, or common elements in a Part 3 condo unit requires strict compliance with Part 3 fire-stopping and structural rules. In many municipalities (like Vancouver, Surrey, or Burnaby), modifications affecting common demising walls or exterior envelopes in Part 3 buildings mandate Architect or Professional Engineer sign-off.

Step 3: Mandatory Architect & AIBC Regulations

Phase 03

Under the *Architects Act* of BC and regulations enforced by the Architectural Institute of British Columbia (AIBC), retaining a Registered Architect is statutorily required when a project exceeds Part 9 thresholds or involves specific major occupancies:

1. All Part 3 Major Occupancy Buildings: New construction, major additions, or structural alterations to Part 3 buildings (exceeding 3 storeys or over 600 m² footprint). 2. Assembly & Care Occupancies: Buildings classified under Group A (Assembly) or Group B (Care & Treatment) regardless of footprint area (subject to specific minor exceptions under the Architects Act regulations). 3. Commercial Tenant Improvements Affecting Exterior Envelopes or Fire Demising Walls: When a commercial alteration impacts shared exterior envelopes, common fire separations, or exit facilities in a multi-tenant Part 3 structure, the municipality and provincial regulations generally mandate an Architect or Coordinating Registered Professional (CRP) to issue Letters of Assurance (Schedule A, B, C-A, C-B).

Part 3 commercial structural steel and fire separation cutaway — **Part 3 Commercial Fire Assemblies:** Engineered structural frame, 2-hour ULC fire separations, automated sprinkler risers, and exit stairwells requiring registered professional Letters of Assurance.

When Does a Part 9 Building Design Package Apply?

Under the Architects Act and the BC Building Code, Part 9 buildings generally fall outside the statutory reservation for registered architects. For residential and small commercial projects—including custom homes, duplexes, Bill 44 SSMUH multiplexes, secondary suite legalizations, laneway houses, and small business tenant improvements—an ASTTBC-registered building designer or qualified drafting firm prepares complete, municipal-ready permit drawing packages directly, coordinating with registered engineers when structural or geotechnical conditions mandate sign-off.

Step 4: Pre-Permit Verification Checklist

Phase 04

Before submitting building permit plans in BC, follow this quick checklist to confirm your compliance path:

Measure Footprint & Count Storeys: Is your building footprint under 600 m² (6,458 sq ft) and 3 storeys or less?
Check Your Occupancy Group: Is your business or residence classified under Group C, D, E, or F2/F3?
Verify Professional Requirements: When a project conforms to Part 9 prescriptive parameters, Canadian Blueprint prepares the complete permit drawing set directly (coordinating with structural or geotechnical engineers when site conditions require). If Part 3 thresholds are triggered, your municipality will confirm which registered professionals (Architect or Coordinating Registered Professional) must submit Letters of Assurance.

Part 3 vs Part 9 BC Building Code blueprint sets and Letters of Assurance comparison — **Code Path Determination:** Clarifying whether your project falls under Part 9 prescriptive housing standards or Part 3 complex engineering determines required professional stamps, municipal review tracks, and overall drafting costs.

Related Guides & Regulatory Resources

Resources

Explore our complete BC building code and municipal permit guide series:

Official Portals:

Canadian Blueprint Inc.

BC Building Design & Permit Drawings

Published August 12, 2026 • Updated September 28, 2026

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