Ice Dams 101: Ventilation, Insulation & Prevention

Why They Happen, How to Stop Them, and When to Call a Professional

If you’ve lived through a few Anchorage winters, you’ve seen ice dams — thick, frozen ridges that form along the roof edge and trap meltwater behind them. They’re one of the most common winter roofing problems in Alaska, and also one of the most misunderstood.

At Anew Roofing, we’ve seen how even a single storm can take years off a roof’s life. Our goal is to help Anchorage homeowners catch small issues early — before they become costly repairs. Here’s what causes them, what you can do about them, and what we do differently when it’s time to fix them for good.

What Causes Ice Dams

It all starts with uneven roof temperatures. Warm air leaking from the attic melts the snow from underneath. That meltwater runs down to the colder eaves, refreezes, and starts stacking into ice. Over time, water gets trapped behind the ice and pushes up under shingles.

Typical causes we see across Anchorage include:
• Insufficient attic insulation, especially over living areas
• Poor ventilation, where warm air can’t escape evenly
• Heat leaks from can lights, bathroom fans, or attic hatches
• Thick snow loads that insulate roof heat and worsen melt-refreeze cycles

Temporary Fixes You Can Try

When an ice dam first appears, there are a few safe, short-term ways to limit the damage before a professional visit:
• Clear 2–3 feet of snow above the eaves with a roof rake from the ground.
• Use calcium-chloride socks laid across the dam to open narrow melt channels.
• Keep gutters and downspouts open so any meltwater has somewhere to go.
Avoid climbing onto the roof or chipping ice directly — it’s dangerous and almost always causes shingle damage.

Why They Keep Coming Back

If ice dams form every winter, the problem isn’t on the roof — it’s under it. In most homes we inspect, we find one or more of these root causes:
• Gaps in attic insulation letting warm air escape
• Blocked soffit vents that trap hot air near the ridge
• Unsealed light fixtures or ductwork leaking warmth upward
• Older homes with little or no air barrier between ceiling and attic
Fixing these permanently takes more than just scraping ice. It’s a balance of insulation, air sealing, and proper ventilation.

How Anew Roofing Solves the Root Cause

When we respond to an ice-dam call, we look at the whole picture — not just the visible ice. We identify insulation gaps, vent restrictions, and areas of air leakage before recommending long-term solutions.
Anchorage weather is extreme, and every home handles it differently. Our goal isn’t just to melt ice — it’s to stop it from coming back next winter.

Long-Term Prevention Tips

If you’re maintaining your own home, these steps go a long way:
• Add insulation to reach at least R-49 where possible.
• Keep attic ventilation clear — both soffit intakes and ridge vents need airflow.
• Seal ceiling penetrations: recessed lights, pipes, hatches, and wiring holes.
• Schedule a winter roof inspection to catch small issues before they grow.

When to Call a Professional

If you’re unsure about the extent of ice buildup or leaks, consider scheduling a professional inspection. A careful look before temperatures drop again can prevent costly damage later.