Why is the eave the most important part of a shingle roof in snow?
The eave takes the largest load of meltwater and refrozen ice, so the starter strip, the first courses and the underlayment there decide whether water gets under the shingles. A correct eave detail is what keeps a thaw from reaching the decking.
Snow that melts on the upper slope runs down to the eave, where the air is cold and the water can refreeze. The ice builds up under the lower courses and pushes water back under the shingles, and that is where most eave leaks begin.
A proper eave detail uses a water-resistant layer that runs up the roof beyond the wall line, with the shingles set over it. That layer stops water from getting under the first courses, and it is worth the extra time on any roof in the snow belt.
What does the underlayment do under a shingle roof?
The underlayment is a second line of protection that sheds water if the shingles are lifted or cracked. In a snow climate it is laid with extra care at the eave and the valleys, where water collects and waits.
A shingle is shaped to shed rain but cannot stop water driven under its edge by wind or held at the eave by ice. The underlayment catches that water and carries it down to the gutter, so the decking stays dry.
Underlayment comes in several types, and the technician chooses the one suited to the roof's pitch and the snow load. Each strip is lapped so water runs over the joint rather than into it.
How do I choose between a shingle color and a shingle profile?
The color is a matter of taste and the look of the house, while the profile affects the weight, the shadow line and how well the shingle lies on the roof. A technician will show the options side by side on the roof's own pitch and light.
Shingle colors can look different in the sun, in the shade and under snow. A sample held against the house in daylight tells you more than a catalogue photograph.
The profile decides whether the roof reads as a flat sheet or a layered surface. A profile that suits the house's style and the roof's pitch often matters more to the finished look than the exact tone.
How does a new shingle roof handle ice dams?
A new shingle roof resists ice dams only as well as the attic does. Ventilation, insulation and air sealing keep the decking cold, and the new eave detail stops any water that does get past the shingles.
A roof with a new covering and a warm attic can still form an ice dam, because the melt starts from below. The attic work that reduces the heat is part of the same plan, and it is covered on the attic ventilation page.
The eave detail and the underlayment give the roof a second line of defense. Together with the attic work, they make a dam less likely to cause a leak inside the house.
How long should a shingle roof be expected to last?
The life of an asphalt shingle roof depends on the product, the underlayment, the ventilation and the climate. No specific life span is promised here, and the technician will explain the expected service of the chosen shingle in the written scope.
Shingles wear through the granules, the sun, the freeze and thaw and the wind. A shingle roof in a snowy climate has to handle the cycle, and the way the eave is detailed matters as much as the shingle itself.
Plan a check after each winter and after each storm. A roof maintenance plan keeps the shingle lines, the flashing and the gutters under review, so a small problem is caught before it spreads.