Every February, the same scene repeats across Collingwood, Wasaga Beach, and the chalets along the escarpment: a ridge of ice builds at the roof edge, icicles get impressive, and then a brown stain spreads across a ceiling. Ice damming causes more interior water damage here than wind, hail, and worn shingles combined.
The frustrating part is that most ice-dam repairs treat the symptom. Here is the whole picture.
What an ice dam actually is
Snow sits on your roof. Heat escaping from the house warms the roof deck, melting the snowpack from below. That meltwater runs down the roof until it hits the overhang at the eaves, which is not heated from below because it sits outside your walls. The water refreezes there, and after a few cycles you have a growing ridge of solid ice.
Now the dam holds a pool of meltwater behind it. Shingles are designed to shed water running downhill, not to hold back standing water. The pool works its way up and under the shingle courses, through the deck, and into your insulation and ceilings.
Why Georgian Bay homes get it worse
Three local factors stack against us:
- Snow load and duration. The snow belt from Blue Mountain through Collingwood keeps a deep snowpack on roofs for months, so there is always fuel for the melt cycle.
- Freeze-thaw whiplash. Bay-moderated temperatures swing across the freezing point constantly. Every swing is another melt-refreeze cycle.
- The housing stock. Converted cottages in Wasaga Beach with thin attic insulation, chalets in The Blue Mountains with cathedral ceilings and nowhere for ventilation to go, and century homes in Thornbury and Meaford with leaky attic hatches. All of them push heat at the roof deck.
If water is coming in right now
Do not chip at the ice with a hatchet, and do not put salt pucks on your shingles. Both destroy the roof to save the roof. The safe sequence:
- Contain the water inside and move belongings clear.
- Photograph everything for insurance.
- Get the snow load above the dam removed and relief channels cut safely. This is emergency roof work; it is our winter bread and butter, and we do it without wrecking the shingles underneath.
The permanent fix is boring, and it works
Ice dams are a heat problem wearing a water costume. The durable solution has three parts:
Air sealing and insulation. Most attics here leak warm air through pot lights, bathroom fans, attic hatches, and top plates. Sealing those and topping up insulation keeps the heat in your house and off the roof deck.
Balanced ventilation. Cold air in at the soffits, warm air out at the ridge. A cold roof deck cannot melt snow. This also happens to be a condition of most shingle warranties.
Ice and water membrane. During a roof replacement, a self-sealing membrane goes on at the eaves, in the valleys, and around penetrations. When a dam forms anyway, the membrane is what stands between the meltwater and your drywall. On Georgian Bay roofs we treat generous membrane coverage as mandatory, not an upgrade.
For homes that fight severe damming year after year, a metal roof changes the game entirely: snow slides off before it can pack into the melt-refreeze cycle.
What it costs
Mid-winter emergency mitigation typically runs a few hundred dollars. The permanent package depends on what your attic needs, but it is almost always cheaper than one properly soaked ceiling, and it usually pays some of itself back in heating costs.
If your roof grows an ice ridge every winter, have someone look at the attic before next season. We inspect the roof and the attic together and give you a written plan with a firm price. Call (249) 499-0101 or request a free quote.