Ice Dams: What Every Pennsylvania Homeowner Needs to Know

What Is an Ice Dam?

An ice dam is a ridge of ice that forms along the edge of your roof, typically at the eaves. It prevents melting snow from draining off the roof properly. As water backs up behind the dam, it can seep under shingles, through the underlayment, and into your home — causing damage to ceilings, walls, insulation, and even the structural framing.

Ice dams are one of the most common and costly winter roofing problems in Pennsylvania, particularly in the Lehigh Valley and Poconos where freeze-thaw cycles are frequent from December through March.

How Ice Dams Form

Ice dams don't form because of cold weather alone. They form because of uneven roof temperatures — and the root cause is almost always inside your home, not outside.

Here's the cycle:

1. 01Heat escapes into the attic through inadequate insulation, air leaks around light fixtures, plumbing stacks, ductwork, or attic hatches
2. 02The warm attic heats the roof deck from below, warming the upper portion of the roof above freezing
3. 03Snow melts on the warm upper roof and water runs down toward the eaves
4. 04The eaves stay cold because they extend beyond the heated living space — there's no warm attic beneath them
5. 05Water refreezes at the cold eaves, forming a growing ridge of ice
6. 06More meltwater backs up behind the ice ridge, pooling on the roof surface
7. 07Standing water finds its way under shingles and into your home

The key insight: ice dams are a ventilation and insulation problem, not a roofing problem. A perfectly installed roof can still develop ice dams if the attic is too warm.

Warning Signs of Ice Dams

Catch ice dams early before they cause interior damage:

• ■Large icicles hanging from the eaves — icicles themselves don't cause damage, but they indicate the conditions for ice dams are present
• ■Ice buildup along the roof edge — a visible ridge of ice at the eaves, especially if it's thicker than 2-3 inches
• ■Water stains on interior ceilings or walls near the roofline, especially after a warm day following snowfall
• ■Peeling paint or bubbling drywall on upper-floor ceilings
• ■Wet or damp insulation in the attic near the eaves
• ■Icicles forming behind the gutter rather than dripping from the gutter edge

The Real Damage Ice Dams Cause

Ice dams aren't just a cosmetic issue. Left unaddressed, they can cause serious structural and financial damage:

The average ice dam insurance claim in Pennsylvania is $5,000 to $10,000, and many homeowners don't realize their policy may not cover damage caused by gradual ice dam formation (as opposed to sudden storm damage).

How to Prevent Ice Dams

Prevention is far cheaper than repair. The three pillars of ice dam prevention are insulation, ventilation, and air sealing — all of which address the root cause: heat escaping into the attic.

1. Proper Attic Insulation

The goal is to keep your attic cold — as close to the outside temperature as possible. When the attic stays cold, snow doesn't melt unevenly, and ice dams can't form.

• ■Pennsylvania energy code requires R-38 minimum attic insulation (about 10-14 inches of fiberglass batts or 10 inches of blown cellulose)
• ■R-49 to R-60 is recommended for optimal performance in the Lehigh Valley climate
• ■Pay special attention to areas above exterior walls at the eaves — this is where insulation is often thinnest and where ice dams start
• ■Never compress insulation against the roof deck — compressed insulation loses R-value

2. Balanced Attic Ventilation

Ventilation works with insulation to keep the attic cold. Fresh cold air enters through soffit vents at the eaves and exits through ridge vents at the peak, flushing out any warm air that does reach the attic.

• ■Soffit vents (intake) and ridge vents (exhaust) should provide roughly equal airflow
• ■Building code minimum: 1 sq ft of net free ventilation per 150 sq ft of attic floor
• ■Install insulation baffles (foam or cardboard channels) at every rafter bay to prevent insulation from blocking soffit vents
• ■Never mix vent types — combining ridge vents with powered attic fans or turbine vents creates competing airflow that short-circuits the system

3. Air Sealing

Even with perfect insulation, warm air from your living space can leak into the attic through gaps and penetrations. These air leaks are often the primary cause of attic heat gain.

Common air leak locations to seal:

• ■Recessed light fixtures (can lights) — use IC-rated airtight housings or retrofit covers
• ■Plumbing vent stacks — seal the gap where pipes penetrate the attic floor with fire-rated caulk
• ■Electrical wiring penetrations — seal with expanding foam
• ■Attic hatch or pull-down stairs — add weatherstripping and an insulated cover
• ■HVAC ductwork — seal all joints with mastic (not duct tape) and insulate ducts in the attic
• ■Bathroom and kitchen exhaust fans — ensure they vent to the exterior, not into the attic

What to Do If You Already Have an Ice Dam

If you spot an ice dam forming on your roof, here's what to do — and what NOT to do:

DO:

• ■Use a roof rake from ground level to remove snow from the first 3-4 feet of the roof edge. This removes the fuel source (snow) that feeds the ice dam. Use a telescoping aluminum roof rake — never a metal shovel.
• ■Create channels in the ice dam by filling a nylon stocking or tube sock with calcium chloride ice melt and laying it perpendicular across the ice dam. The calcium chloride will slowly melt a channel for water to drain. Do NOT use rock salt (sodium chloride) — it damages shingles and kills plants below.
• ■Place buckets under any interior leaks and move furniture and valuables away from the affected area.
• ■Document the damage with photos for your insurance claim — photograph the ice dam from outside and any interior water damage.
• ■Call a professional for steam removal if the ice dam is large or causing active leaking.

DO NOT:

• ■Do NOT climb on a snow-covered or icy roof — this is extremely dangerous and the #1 cause of winter roofing injuries
• ■Do NOT hack at ice dams with a hammer, axe, or ice pick — you will damage shingles and the roof deck
• ■Do NOT use a pressure washer or hot water — water refreezes and makes the problem worse
• ■Do NOT pour boiling water on the ice — thermal shock can crack shingles
• ■Do NOT use rock salt or sodium chloride — it corrodes metal flashing and gutters and damages shingles

Ice & Water Shield: Your Last Line of Defense

Even with perfect insulation and ventilation, extreme winters can still produce some ice damming. That's where ice and water shield comes in — a self-adhering waterproof membrane installed directly on the roof deck during roof replacement.

Pennsylvania building code requires ice and water shield along the eaves, extending at least 24 inches past the interior wall line. This means if an ice dam does form and water backs up under the shingles, the membrane prevents it from reaching the wood deck and entering your home.

At RoofOps, we install ice and water shield:

• ■Along all eaves (code minimum)
• ■In all valleys (where two roof planes meet)
• ■Around all penetrations (chimneys, skylights, vent pipes)
• ■Along rakes (sides of the roof) in high-wind areas

For homes with a history of ice dam problems, we can install full-deck ice and water shield — covering the entire roof surface for maximum protection. This is also a requirement for FORTIFIED Roof designation (Option 3 deck sealing).

When Your Roof Needs Professional Attention

Some ice dam situations require professional intervention:

• ■Active interior leaking — call immediately for emergency tarping
• ■Ice dams larger than 6 inches thick — professional steam removal is the safest option
• ■Recurring ice dams every winter — indicates a systemic insulation/ventilation problem that needs professional assessment
• ■Visible damage to shingles or flashing after ice dam removal — schedule a spring inspection
• ■Sagging gutters or fascia from ice weight — these need repair before next winter

The RoofOps Approach to Ice Dam Prevention

When we replace a roof, we build in ice dam protection at every layer:

1. 01Inspect and repair the roof deck — ensuring a solid, dry foundation
2. 02Install ice and water shield along all eaves, valleys, and penetrations (minimum 24" past interior wall line)
3. 03Use synthetic underlayment fastened with Stinger NailPac cap nails for maximum wind and water resistance
4. 04Verify attic ventilation — we check that soffit and ridge vents are properly balanced and unobstructed
5. 05Flag insulation issues — if we see inadequate insulation or air leaks during our inspection, we'll recommend addressing them before or during the roof replacement

A new roof alone won't prevent ice dams if the attic is poorly insulated and ventilated. But a properly installed roof with adequate ice and water shield will prevent ice dam water from entering your home — even when conditions are severe.

Schedule a Free Winter Roof Inspection

Concerned about ice dams on your roof? RoofOps offers free inspections year-round. We'll assess your roof condition, check your attic ventilation, and recommend the most cost-effective solutions for your specific situation.

Call (835) 248-0004 or schedule your free inspection today.

RoofOps is a veteran-owned, PA licensed (HIC #200014) roofing contractor serving Bethlehem, Nazareth, Allentown, Easton, and the greater Lehigh Valley, Bucks County, Montgomery County, and Poconos region.