Ice Dams in NJ & NY: Causes, Prevention, and When to Call a Pro
Summary: Ice dams happen when heat from the attic melts roof snow and refreezes at cold eaves, forcing water up under shingles. The result? Leaks, interior stains, and damaged insulation. Here’s how to prevent them—and what to do if they’ve already started.
What Causes Ice Dams?
Ice dams form when three conditions meet:
- Heat loss from the home warms the roof deck.
- Snow blankets the roof.
- Cold eaves keep edges below freezing, so melted snow refreezes and creates a “dam.”
As the dam grows, water backs up and can slip beneath shingles, wetting the underlayment, decking, and attic insulation.
How to Prevent Ice Dams (Homeowner Checklist)
- Insulate & air-seal the attic
Seal gaps around light fixtures, bath fans, attic hatches, and plumbing penetrations. Add insulation to meet code/energy-star levels. Air-sealing reduces heat escaping to the roof deck, which is the root cause of dams. - Balance attic ventilation (intake + exhaust)
Proper soffit intake plus ridge exhaust helps keep attic temps closer to outdoors, limiting melt/refreeze cycles. We size the Net Free Area (NFA) and use components like GAF Cobra® ridge vent. - Install an eaves leak barrier
Along eaves/valleys, install a self-adhered membrane (e.g., GAF WeatherWatch®) extending far enough up the roof per code and local climate. - Keep gutters clear
Gutters don’t cause ice dams—but debris can worsen overflow and ice formation at the edge. - Direct bath/kitchen vents outdoors
Never vent into the attic. Warm, moist air feeds ice-dam conditions and mold risk.
What Not to Do
- Don’t hack at ice with shovels or picks—easy way to damage shingles and flashing.
- Skip rock salt on roofs—it’s corrosive and can stain/damage landscaping and metals.
- Avoid quick “heat cable only” fixes without addressing insulation/ventilation. Cables can help specific trouble spots but aren’t a substitute for correcting the root causes.
When to Call a Pro
- Visible ceiling stains or active dripping
- Wet or compressed attic insulation
- Recurring heavy icicles or damming year after year
- Ice dams even after adding insulation or basic ventilation upgrades
We can safely remove snow, evaluate attic/roof conditions, verify ventilation and insulation levels, and install the right combination of leak barrier, intake/exhaust, and air-sealing.
Service Areas
We help homeowners across New Jersey & New York, including Bergen, Passaic, Essex, Morris, and Hudson Counties (NJ) and Westchester & Rockland (NY).
Why Choose Donny’s Roofing & Home Improvement?
- GAF Master Elite® Certified
- Proper attic ventilation design and code-compliant leak barriers
- Detailed photos, clean job sites, and warranty registration
Frequently Asked Questions
How much leak barrier should be installed at the eaves?
Local code and manufacturer specs drive this; in cold regions it often extends from the eave up to at least 24″ inside the warm wall line. We confirm on site.
Can new gutters fix ice dams?
Clean, properly pitched gutters help manage meltwater, but they don’t solve attic heat loss or ventilation issues that cause dams.
Do metal roofs get ice dams?
Less frequently, but yes—any roof with heat loss and snow cover can dam at cold edges.
Call to Action
Protect your home this winter. Free inspections & estimates 7 days a week.
📞 (973) 333-6364 • 📧 sales@donnysroofing.com