We all have that picture-perfect image of winter in Anne Arundel County: fresh snow on the lawn, a fire in the hearth, and long, glistening icicles hanging from the roof edge.
It looks like a holiday card, but as roofing professionals, when we see those massive icicles, we don’t see “cozy.” We see a warning sign.
Those icicles are often the visible tip of an Ice Dam—a winter phenomenon that can silently cause thousands of dollars in water damage to your home’s interior, even when it’s freezing outside.
Here is what is actually happening on your roof, and why you need to address it before the next deep freeze.
Table of Contents
- What is an Ice Dam? (The Science of the Melt)
- Why Are Ice Dams Dangerous?
- The Real Culprit: It’s Usually Not the Roof!
- What NOT To Do
- How Colonial Roofing Can Help
What is an Ice Dam? (The Science of the Melt)
An ice dam is exactly what it sounds like: a ridge of ice that forms at the edge of your roof and prevents melting snow (water) from draining off.
Here is the cycle that creates them:
- Heat Loss: Warm air from your living space escapes into your attic.
- The Melt: This warm air heats the upper part of your roof deck, melting the snow sitting on top of your shingles.
- The Runoff: That melted water runs down the slope of the roof under the snowpack.
- The Freeze: When that water reaches the eaves (the overhang of your roof), it hits a cold spot. Since the eaves aren’t over a heated living space, they remain freezing cold. The water refreezes instantly, building up a layer of ice.
As this cycle repeats, the ice builds up higher and higher, forming a “dam” at the gutter line.
Why Are Ice Dams Dangerous?
The ice itself isn’t the main problem—it’s the water behind it.
Your roof shingles are designed to shed water downward. They are layered like fish scales to let gravity do the work. However, shingles are not designed to be submerged in standing water.
When an ice dam blocks the gutters, the melting water coming down the roof has nowhere to go. It backs up and forms a pool. Eventually, that water travels upward (backward) underneath your shingles.
Once the water gets past the shingles, it soaks the roof decking, ruins the underlayment, and drips into your attic. This leads to:
- Wet, ineffective insulation.
- Rotting roof rafters.
- Brown water stains on your interior ceilings and walls.
- Mold growth in the attic.
The Real Culprit: It’s Usually Not the Roof!
This is the part that surprises most Crownsville homeowners. If you have ice dams, you don’t necessarily have a roofing problem—you likely have an insulation and ventilation problem.
A healthy winter roof should be the same temperature as the air outside. If your roof is warm enough to melt snow when it is 25°F outside, you are losing expensive heat from your home into your attic.
The solution usually involves sealing air leaks from the house into the attic, adding insulation, and ensuring your soffit and ridge vents are working correctly to keep cold air circulating under the roof deck.
What NOT To Do
If you see an ice dam forming, your instinct might be to knock it down. Please, do not do this.
- Don’t hack away with a shovel or pickaxe: We have seen many homeowners accidentally slice through their own shingles or rip off gutters trying to break the ice.
- Don’t use rock salt: Standard salt can damage your shingles and kill the plants below your drip line when it washes off.
- Don’t climb a ladder in winter: A ladder on an icy driveway is a recipe for a hospital visit.
How Colonial Roofing Can Help
Winter is actually a great time to diagnose these issues because the “symptoms” (icicles and uneven snow melt) are clearly visible.
We don’t just look at the shingles; we look at the whole system. We can assess your attic ventilation and insulation to stop the heat loss that causes the dams in the first place.
Do you see large icicles forming on your eaves? Don’t wait for the ceiling spot to appear.
Call Colonial Roofing Co today at 410-729-3550. Let’s keep the cold outside and the water off your ceilings this winter.
