Ice dams form when heat escaping from your attic melts snow on the upper part of your roof, which then refreezes at the colder eaves, building up a ridge of ice that traps water behind it. This trapped water can back up under shingles and leak into your home, making ice dams one of the more damaging winter problems homeowners face without realizing the cause until it's already a leak.
The root cause is almost always heat loss from the attic, not the outdoor temperature itself. A well-insulated attic stays close to outdoor temperature, so snow on the roof melts evenly and slides or evaporates without refreezing into a dam. Poor attic insulation or ventilation lets warm air escape upward, creating the uneven melting pattern that causes ice dams to form in the first place.
Prevention starts well before winter, with proper attic insulation and ventilation being the most effective long-term fix. This isn't something a snow removal company handles, but it's worth addressing with a contractor if ice dams have been a recurring problem, since no amount of snow clearing fixes an underlying insulation issue.
Once ice dams do form, careful removal matters. Aggressive chipping can damage shingles and cause more harm than the dam itself. Professional roof snow removal using proper techniques, or calcium chloride socks laid across the dam to create channels for water to drain, are safer approaches than DIY chipping with a hammer or shovel.
Thames Valley Snow can advise London homeowners on managing existing ice dams safely and can refer clients to trusted local contractors for the underlying insulation fixes that prevent dams from forming year after year. Addressing the root cause, not just the symptom, is what actually solves this problem long-term.
Keep the ground safe below
Ice dams often lead to dripping and icicles over entrances, which can freeze into slick patches on steps and walkways. Salting and walkway clearing help keep those areas safe.
Know what a snow company can and cannot do
Driveway plow crews do not usually work on roofs. For roof snow or ice dams, contact a roofer or a company that specializes in roof snow removal, and avoid climbing on an icy roof yourself.
Prevention for next year
Ice dams are usually caused by heat escaping into the attic. Insulation and ventilation are worth checking in the spring.
Frequently asked questions
Will you clear icicles over my door?
Ask the team. Roof work is not part of standard plans.
Does salting cover refreeze from roof melt?
Seasonal salting ($175) includes refreeze visits on the surfaces you have covered.
What's included… and what's extra
A Thames Valley Snow seasonal residential plan starts from $650 for a standard driveway. It covers clearing the driveway every time snowfall reaches the trigger depth in your agreement, plus the windrow the city plow leaves at the end of the driveway. Larger driveways are priced on our snow removal prices page.
Popular add-ons, priced per season: walkway and steps $150–175, salting $175, priority service $125, pet-safe salt $120, driveway extension $95 and city sidewalk clearing $90. Add only what your property needs; everything is listed on the quote so there are no surprises. Get your fixed price or call or text (548) 888-8702.
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Seasonal snow removal from $650 + HST. Automatic at 5 cm, photo after every visit.
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