What Are Ice Dams?

Ice dams are ridges of ice that form at roof eaves, preventing melting snow from draining. Water backs up behind the dam and leaks into your home, causing thousands of dollars in damage to ceilings, walls, insulation, and belongings.

In Fraser Valley — particularly Hope, Harrison Hot Springs, and Mission — ice dams are a recurring winter problem. Understanding the science behind them is the first step to prevention.

The Science: How Ice Dams Form

Step 1: Heat Escapes from Living Space

Heat from your home rises into the attic. Even with insulation, some heat escapes through the ceiling. This heat warms the underside of the roof deck.

Step 2: Snow Melts on Warm Roof

The warmed roof deck melts the bottom layer of snow. Meltwater runs down the roof slope toward the eaves.

Step 3: Water Refreezes at Cold Eaves

The eaves (roof overhangs) are not above heated space. They remain at outdoor temperature. When meltwater reaches the cold eaves, it refreezes, forming ice.

Step 4: Ice Dam Grows

As more meltwater flows down and refreezes, the ice dam grows larger, creating a barrier that prevents drainage.

Step 5: Water Backs Up Under Shingles

Meltwater pools behind the ice dam. It has nowhere to go, so it backs up under shingles and penetrates the roof, leaking into your home.

Why Fraser Valley Is Vulnerable

1. Heavy, Wet Snow ("Cascade Concrete")

Fraser Valley snow is wet and heavy — 12 inches can deposit 2,000+ pounds per square on a roof. This dense snow insulates the roof, trapping heat underneath and accelerating melting.

2. Rapid Temperature Swings

Hope and Harrison experience rapid temperature fluctuations. A sunny day can melt snow even when air temperature is below freezing. Nighttime refreezing creates perfect ice dam conditions.

3. Older Homes with Poor Insulation

Many Fraser Valley homes were built before modern insulation standards. Heat loss through ceilings is significant, creating ideal conditions for ice dams.

The Three-Part Prevention Strategy

1. Stop Heat Loss (The Root Cause)

Ice dams form because heat escapes into the attic. Stop the heat loss, and you eliminate ice dams.

Attic Insulation:

• Current Standard: R-50 (16-18 inches of fiberglass or cellulose)
• Older Homes: Often have R-20 or less
• Impact: Upgrading from R-20 to R-50 reduces heat loss by 60%

Air Sealing:

• Seal gaps around recessed lights, plumbing vents, chimneys
• Use spray foam or caulk to seal ceiling penetrations
• Install weatherstripping on attic access hatches

Why This Matters:

Insulation slows heat transfer, but air leaks bypass insulation entirely. A 1-inch gap around a chimney can lose as much heat as 100 square feet of un-insulated ceiling.

2. Ventilate the Attic (Keep Roof Deck Cold)

Even with perfect insulation, some heat will enter the attic. Ventilation removes this heat, keeping the roof deck at outdoor temperature.

The 1:300 Rule:

• 1 square foot of net free ventilation area per 300 square feet of attic floor
• 50% intake (soffit vents) + 50% exhaust (ridge vents)

Example:

• 1,500 sq ft attic = 5 sq ft NFA required
• 2.5 sq ft intake + 2.5 sq ft exhaust

Common Ventilation Mistakes:

• Blocked Soffit Vents: Insulation pushed into eaves blocks airflow
• Imbalanced System: Too much exhaust, not enough intake (or vice versa)
• No Baffles: Insulation blocks airflow path from soffit to ridge

3. Install Ice & Water Shield (Backup Protection)

Even with perfect insulation and ventilation, ice dams can still form during extreme weather. Ice & water shield is your last line of defense.

What It Is:

Self-adhering rubberized membrane installed at eaves. It creates a 100% waterproof seal, preventing water from penetrating even if it backs up under shingles.

Code Requirements vs. Our Standards:

• BC Building Code: 36 inches (3 feet) at eaves in snow zones
• Our Standard in Hope/Harrison: 72 inches (6 feet) — we double it
• Why: Ice dams can extend 4-6 feet up a roof in severe winters

Cost vs. Value:

• 36" ice & water shield: $300-500
• 72" ice & water shield: $500-800
• Ice dam water damage: $5,000-15,000

The $200-300 upgrade is the best insurance you can buy.

Emergency Solutions (When Ice Dams Form)

1. Heat Cables (Temporary Fix)

What They Are:

Electric heating cables installed in a zigzag pattern along eaves. They melt channels through ice, allowing water to drain.

Effectiveness:

• Very effective at melting existing ice dams
• Prevents water backup and leaks
• Requires electricity (operating cost $50-150 per winter)

Limitations:

• Treats symptoms, not cause
• Must be activated before/during ice dam formation
• Cables can be damaged by falling ice or debris

Our Recommendation:

Heat cables are a band-aid. The real fix is insulation and ventilation. However, they're useful for historic homes where insulation upgrades aren't feasible.

2. Roof Raking (Manual Snow Removal)

What It Is:

Using a roof rake (long-handled tool) to pull snow off the roof from the ground.

Effectiveness:

• Removes snow before it can melt and form ice dams
• No electricity required
• Immediate results

Limitations:

• Labor-intensive
• Only reaches first 10-15 feet of roof
• Can damage shingles if done improperly

How to Rake Safely:

• Pull snow straight down (don't scrape sideways)
• Leave 1-2 inches of snow on roof (protects shingles)
• Focus on first 6 feet from eaves (where ice dams form)

3. Professional Ice Dam Removal

What It Is:

Professionals use low-pressure steam to melt ice dams without damaging shingles.

Cost: $400-800 per visit

When It's Worth It:

• Active leak (water entering home)
• Large ice dam (6+ inches thick)
• Unsafe to access (steep roof, icy conditions)

DO NOT:

• Use salt or ice melt (damages shingles and gutters)
• Chip ice with hammer or axe (damages shingles and flashing)
• Use hot water (refreezes immediately, makes problem worse)

Long-Term Solutions: What Actually Works

Option 1: Insulation + Ventilation Upgrade

Cost: $2,000-5,000 (typical attic)

What's Included:

• Air sealing (gaps, penetrations)
• Insulation upgrade to R-50
• Ventilation baffles
• Additional soffit/ridge vents if needed

Effectiveness: 90-95% reduction in ice dams

Payback:

• Energy savings: $300-600/year
• Avoided ice dam damage: $5,000-15,000 (one-time)
• ROI: 2-5 years

Option 2: Metal Roofing

Cost: $25,000-35,000 (average home)

How It Works:

• Smooth metal surface allows snow to slide off
• No snow = no melting = no ice dams
• Self-clearing within days of snowfall

Effectiveness: 95-99% reduction in ice dams

When It Makes Sense:

• You need a new roof anyway
• You're in Hope or Harrison (extreme snow zones)
• You're tired of ice dam hassles

The Bottom Line

Ice dams are a symptom of heat loss. Heat cables and roof raking treat the symptom. Insulation and ventilation fix the cause.

At RJ Roofing Bros, we'll assess your specific situation and recommend the most cost-effective solution. Sometimes that's heat cables. Sometimes it's insulation. Sometimes it's a new roof. We'll give you honest advice.

Ice dam problems? Call (604) 997-1292 for a free assessment.