Introduction: Why Building Codes Matter

The BC Building Code sets minimum standards for roofing to ensure safety, durability, and energy efficiency. Understanding these requirements helps you verify your contractor is doing the job right and protects your investment.

CURRENT CODE: BC BUILDING CODE 2018

What Version Applies?

BC Building Code 2018:

• Current version in effect across BC
• Based on National Building Code of Canada 2015
• BC-specific amendments for climate and seismic conditions
• Municipalities may have additional requirements

ROOFING MATERIAL REQUIREMENTS

Fire Ratings (Critical)

Class A Fire Rating (Required for Most Areas):

• What it means: Highest fire resistance rating
• Required for: Urban areas, wildfire interface zones
• Materials that qualify:
  • Asphalt shingles (fiberglass mat)
  • Metal roofing
  • Concrete/clay tiles
  • Fire-retardant treated wood shakes

Class B and C Ratings:

• Lower fire resistance
• May be allowed in rural areas (check local bylaws)
• Untreated wood shakes typically Class C

Fraser Valley Requirements:

• Hope, Chilliwack, Abbotsford: Class A required in urban areas
• Wildfire interface zones: Class A mandatory
• Rural areas: May allow Class B/C (verify with local building department)

Wind Resistance

Wind Load Requirements:

• Fraser Valley wind zone: Moderate (1 in 50 year wind = 80-100 km/h)
• Shingle rating required: Minimum 110 mph (177 km/h)
• Installation: Must follow manufacturer specs for wind resistance

High-Wind Areas:

• Exposed hilltops, coastal areas
• May require enhanced fastening (6 nails vs. 4)
• Sealed shingles (adhesive strip)

Snow Load

Fraser Valley Snow Loads:

• Hope: 2.4 kPa (moderate)
• Chilliwack: 2.0 kPa
• Abbotsford: 1.8 kPa
• Higher elevations: Up to 4.0+ kPa

What This Means:

• Roof structure must support snow load
• Affects rafter/truss sizing
• Important for deck replacement decisions

VENTILATION REQUIREMENTS

The 1:300 Rule

Code Requirement:

• Ratio: 1 square foot of vent per 300 square feet of attic
• Example: 1,500 sq ft attic needs 5 sq ft of ventilation
• Split: 50% intake (soffit), 50% exhaust (ridge/gable)

Acceptable Ventilation Systems:

• Ridge vent + soffit vents: Best (continuous airflow)
• Gable vents + soffit vents: Acceptable
• Roof vents + soffit vents: Acceptable (multiple vents needed)
• Power vents: Allowed but not recommended (can create negative pressure)

Why Ventilation Matters

Summer:

• Reduces attic temperature (can reach 70°C without ventilation)
• Extends shingle lifespan
• Reduces cooling costs

Winter:

• Prevents ice dams (keeps roof deck cold)
• Prevents condensation (removes moist air)
• Prevents mold and rot

UNDERLAYMENT REQUIREMENTS

Code Minimums

Standard Requirement:

• #15 felt paper: Code minimum (not recommended)
• Synthetic underlayment: Exceeds code (recommended)
• Coverage: Entire roof deck

Ice & Water Shield

Code Requirement:

• Minimum coverage: 36 inches (900 mm) from eave edge
• Valleys: Required (36 inches each side)
• Penetrations: Required around chimneys, skylights

Best Practice (Exceeds Code):

• Eaves: 72 inches (6 feet) from edge
• Valleys: Full length
• Reason: Fraser Valley ice dams can extend 4-6 feet

FLASHING REQUIREMENTS

Valley Flashing

Code Requirements:

• Material: Corrosion-resistant metal (galvanized steel, aluminum, copper)
• Width: Minimum 24 inches (610 mm)
• Underlayment: Ice & water shield required beneath

Step Flashing (Walls)

Code Requirements:

• Material: Corrosion-resistant metal
• Size: Minimum 5 inches (125 mm) each direction
• Installation: One piece per shingle course, overlapping
• Counter-flashing: Required over step flashing (protects from water)

Chimney Flashing

Code Requirements:

• Base flashing: Metal flashing at chimney base
• Counter-flashing: Embedded in chimney mortar
• Cricket: Required for chimneys wider than 30 inches (diverts water)

FASTENING REQUIREMENTS

Shingle Nailing

Code Minimums:

• Number of nails: 4 per shingle (standard conditions)
• High-wind areas: 6 per shingle
• Nail type: Galvanized roofing nails, minimum 1-1/4 inch length
• Placement: Per manufacturer specifications

Fraser Valley Best Practice:

• 6 nails per shingle: Better wind resistance
• Reason: Outflow winds, atmospheric rivers
• Cost: Minimal (50% more nails = $200-300 on typical roof)

Deck Fastening

Code Requirements:

• Plywood/OSB thickness: Minimum 3/8 inch (residential)
• Fastening: 8d nails or equivalent screws
• Spacing: 6 inches on edges, 12 inches in field
• Gaps: 1/8 inch between sheets (expansion)

ENERGY EFFICIENCY REQUIREMENTS

Attic Insulation

BC Energy Step Code (Optional but Encouraged):

• Minimum R-value: R-40 for attics (climate zone 4)
• Fraser Valley: Climate zone 4
• Typical insulation: 12-14 inches of blown fiberglass/cellulose

Why It Matters for Roofing:

• Prevents ice dams (reduces heat loss through roof)
• Must not block soffit vents (use baffles)
• Affects ventilation requirements

PERMIT REQUIREMENTS

When Permits Are Required

Full Roof Replacement:

• Required: Yes, in most municipalities
• Cost: $100-300 (varies by municipality)
• Inspection: May require inspection before covering deck

Repairs:

• Minor repairs: Usually no permit (replacing a few shingles)
• Major repairs: May require permit (re-decking section, structural)
• Check with municipality: Requirements vary

Fraser Valley Municipalities

Hope:

• Permit required for full replacement
• Contact: District of Hope Building Department

Chilliwack:

• Permit required for full replacement
• Online permit application available

Abbotsford:

• Permit required for full replacement
• May require energy efficiency compliance

COMMON CODE VIOLATIONS

What We See Often

1. Inadequate Ice & Water Shield:

• Violation: Only 36 inches at eaves (code minimum)
• Problem: Ice dams extend 4-6 feet in Fraser Valley
• Solution: Extend to 72 inches

2. Insufficient Ventilation:

• Violation: Less than 1:300 ratio
• Problem: Premature shingle failure, ice dams, mold
• Solution: Add ridge vent or additional vents

3. Improper Nailing:

• Violation: Nails too high (above seal strip)
• Problem: Shingles blow off in wind
• Solution: Follow manufacturer nailing diagram

4. Missing Step Flashing:

• Violation: Caulk used instead of step flashing
• Problem: Leaks within 1-2 years
• Solution: Install proper metal step flashing

MANUFACTURER SPECS vs. CODE

Which Takes Precedence?

The Rule:

• Code: Sets minimum standards
• Manufacturer specs: Often exceed code
• Warranty requirement: Must follow manufacturer specs
• Best practice: Follow whichever is more stringent

Example:

• Code: 4 nails per shingle
• GAF spec: 6 nails for wind warranty
• We install: 6 nails (to maintain warranty)

The Bottom Line

BC Building Code sets minimum standards, but best practice often exceeds code. Understanding these requirements helps you verify your contractor is doing the job right.

At RJ Roofing Bros, we exceed code minimums as standard practice: 72-inch ice shield (not 36), 6-nail protocol (not 4), synthetic underlayment (not felt), and proper ventilation (1:300 or better). We pull permits, pass inspections, and build roofs that last.

Questions about code compliance? Call (604) 997-1292