3 Feet of Ice & Water in Vermont vs. Full Ice & Water: What’s Best for Your Roof in Harsh Winter Conditions?

When winter unleashes its worst—blizzards, ice storms, and deep freezes—your roof takes the brunt of it. Homeowners and roofing professionals alike debate whether installing 3 feet of ice and water shield or going with a full ice and water coverage is the better choice for protecting a home.

Let’s break down the pros and cons of each approach, especially in extreme winter conditions, so you can make the best decision for your roof.

What is Ice & Water Shield?

Ice and water shield is a self-adhering, waterproof underlayment that provides an extra layer of defense against ice dams, wind-driven rain, and leaks. Unlike traditional roofing felt, it seals around nail penetrations, preventing water from sneaking in.

Option 1: 3 Feet of Ice & Water Shield

Most building codes require at least 3 feet of ice and water shield along the eaves in snow-prone areas. This is meant to protect the lower edge of the roof, where ice dams typically form.

Pros:

✅ Meets Code – In many regions, this is the minimum requirement, making it a cost-effective way to stay compliant.
✅ Cost-Effective – Uses less material, keeping installation costs lower.
✅ Protects the Most Vulnerable Area – Shields the area most prone to ice damming.

Cons:

❌ Limited Protection – Ice dams can back up farther than 3 feet, especially on low-slope roofs or in extreme snowfall.
❌ Leaks Can Still Occur – Water can find its way higher up the roof, where there’s no additional barrier.
❌ Not Ideal for Severe Winters – In areas with persistent snow cover, freezing rain, and prolonged cold, this may not be enough.

Option 2: Full Ice & Water Shield Coverage

For ultimate protection, some homeowners and roofing contractors choose to install ice and water shield over the entire roof deck, rather than just along the eaves.

Pros:

✅ Maximum Waterproofing – Every part of the roof is sealed against water infiltration.
✅ Superior Ice Dam Protection – If ice dams extend beyond 3 feet, the entire roof is still protected.
✅ Extra Defense Against Wind-Driven Rain – Helps in extreme storms where rain might be forced under shingles.
✅ Longer Roof Lifespan – Reduces the risk of rot and leaks, keeping the roof structure in better condition.

Cons:

❌ Higher Cost – Full coverage means using significantly more material and labor, increasing installation costs.
❌ May Not Be Necessary in Milder Climates – In areas with lighter snowfall or minimal ice dam risk, full coverage could be overkill.

Which is Best for Harsh Winter Conditions?

If your region experiences heavy snowfall, frequent ice storms, or extreme cold, then full ice and water coverage is the better long-term investment. It prevents water infiltration across the entire roof, significantly reducing the chances of leaks caused by ice dams.

However, if you’re in an area with moderate winters and good attic ventilation, 3 feet of ice and water shield might be sufficient while keeping costs down.

Final Verdict
• For homeowners in extreme winter zones (such as the northern U.S. and Canada), full ice and water coverage offers the best protection.
• For milder climates or budget-conscious projects, 3 feet of coverage may be enough to meet code and protect the most vulnerable areas.

Pro Tip: Always pair ice and water shield with proper attic insulation and ventilation to minimize ice dam formation in the first place.

Need professional advice on the best protection for your roof? Contact us today at Snow Country Roofing for an expert consultation!