November 28, 2025 | Mohawk Valley Energy Solutions

When winter hits, many homeowners worry about one of the most common (and costly) cold-weather problems: ice dams. These thick ridges of ice that build up along the edges of your roof can lead to leaks, damaged shingles, soaked insulation, mold growth, and expensive repairs.

Most people assume that simply adding more insulation is the solution. But here’s the truth:

To truly protect your home, air sealing must come first.

In this article, we break down what ice dams are, why they form, and why air sealing is the critical first step before adding insulation.

Ice dams happen when heat escapes from the inside of your home into the attic. That warm air melts the snow on your roof, and as the water runs down to the colder roof edges, it refreezes, creating a buildup of ice.

Over time, that ice forces melting snow back under your shingles and into your home.

But the #1 cause is uncontrolled warm air leaking through gaps, cracks, and openings in the top of your home.

Air sealing is the process of closing the hidden gaps in your home that allow warm indoor air to escape into the attic. These gaps are typically found around:

Even small openings allow significant heat loss—enough to melt roof snow and create the perfect conditions for ice dams.

Insulation slows heat transfer, but it does not stop warm air from leaking through cracks. If you skip air sealing, the warm air will simply move through or around the insulation and into the attic.

Even with high R-value insulation, air leaks can still raise attic temperatures, melt snow, and trigger ice dam formation. This past month, we removed tons of fiberglass insulation from a house that had very bad ice dams last year, but no air sealing was previously done.

Stopping air leaks can reduce heating and cooling costs by 15–25%, often more than insulation alone.

Air movement reduces insulation performance. When the space is sealed, insulation maintains its full R-value and does its job effectively.

Warm, moist indoor air leaking into a cold attic leads to condensation—moist insulation, mold growth, and even wood rot. Air sealing eliminates this risk.

When done in the correct order (air seal first, then insulate), your home benefits from:

This “home performance” approach is the gold standard recommended by energy auditors and building science experts.

At Mohawk Valley Energy Solutions, we take a building-science approach to every attic project:

This approach ensures long-lasting results and protection against winter damage.

Insulation is important, but air sealing is essential. If you want to eliminate ice dams, improve comfort, and reduce heating bills, sealing attic air leaks is the first step and the foundation of an efficient home.