Why Syracuse Roofs Fail at the Eaves and Not in the Middle

Because the failure here is ice rather than shingle wear. January averages 23.6 degrees, snow sits on the roof for weeks, and the temperature crosses freezing roughly 84 times a year, so heat escaping the house melts snow that refreezes at the cold overhang and backs water up under the covering.

The numbers that produce the ice

Syracuse averages 123.8 inches of snow a year under the 1991 to 2020 climate normals measured at Hancock International Airport, across 66.4 days a year with measurable snowfall. In a normal winter there is an inch or more on the ground on 60.3 days between December and February, and five inches or more on 31.4 of those days, so for about a month of every winter the roof is carrying a real load rather than a dusting. The normal January mean temperature is 23.6 degrees Fahrenheit, nine degrees below freezing, which means snow that lands in January is not going anywhere on its own. What melts it is heat escaping from the house. Then the freeze and thaw count: the city records 129.5 days a year with a minimum at or below freezing but only 45.7 days that never rise above it, implying roughly 84 days a year when the temperature crosses freezing in both directions. Meltwater runs down the warm part of the roof, reaches the overhang beyond the heated wall where there is nothing underneath to keep it liquid, freezes, and the ridge of ice that builds holds the next melt back until it finds a way under the covering. Add the loading pattern, 9.9 days in January, 8.1 in December and 7.4 in February with an inch or more of snowfall in a single day, and you have flashings and fasteners cycled dozens of times a winter. Fatigue at the eave, the valley and the step flashing is a wear pattern here, not an accident.

The one line item a cheap quote leaves out

Section R905.1.2 of the Residential Code of New York State requires that, in areas with a history of ice forming along the eaves causing a backup of water, an ice barrier be installed for asphalt shingles, metal roof shingles, mineral-surfaced roll roofing, slate and slate-type shingles, wood shingles and wood shakes. It must be not fewer than two layers of underlayment cemented together, or a self-adhering polymer-modified bitumen sheet, used in place of normal underlayment, and it must extend from the lowest edge of all roof surfaces to a point not less than 24 inches inside the exterior wall line of the building. Read that measurement carefully, because it is not measured from the gutter. It runs to a point 24 inches past the inside face of the exterior wall, so any overhang is added on top, and on a house with deep eaves that means two courses of membrane rather than one. Note also the phrase all roof surfaces. A quote that says ice and water shield at the eaves and stops there is not yet a specification. Ask how far up the slope it runs, how many courses that works out to on your roof, and what is happening in the valleys and around the chimney.

Whether it is required at your address is a municipal decision

This is the part that is almost never explained locally. Section R301.2 of the Residential Code of New York State states that additional criteria shall be established by the authority having jurisdiction and set forth in Table R301.2. That table is where the local ground snow load, the wind design speed, the frost line depth and the yes or no answer on whether ice barrier underlayment is required are recorded, and it is filled in by the municipality, not by the state. The state does not leave the municipality guessing about how to fill it in: Department of State Technical Bulletin TB-1009-RCNYS instructs each authority having jurisdiction to enter YES in the ice barrier underlayment column where there is a history of local damage from the effects of ice damming. So there is no single Onondaga County snow load and no single county answer on the ice barrier, and elevation moves the load as well: under 19 NYCRR 1220.3(a) a site above 1,000 feet carries a ground snow load 2 pounds per square foot higher for every 100 feet above that, which is why an address on high ground south or east of the city is designing to more than the lake plain is. The binding numbers for your address come from your own town or village code office, which makes for a short and very useful phone call: does our Table R301.2 require ice barrier underlayment, and what ground snow load did you record? When you are comparing quotes, ask which jurisdiction's Table R301.2 the contractor designed to. If the answer happens to be that your table does not require the barrier, the 84 freeze crossings outside have not changed, and specifying it anyway is a decision you can make on the evidence rather than on the minimum.

Half of the fix is inside the attic

Section R806 of the Residential Code of New York State requires ventilation of enclosed attics and enclosed rafter spaces, and requires not less than one inch of clear space between the insulation and the roof sheathing where eave or cornice vents are installed. That one inch is where most local ice dams are actually born. Insulation pushed tight against the sheathing at the eave blocks the intake air, the deck above it stays warm, the snow on it melts, and the water refreezes over the cold overhang. A new covering laid over a blocked soffit will dam again the first winter, so baffles at the eave belong in the scope of work rather than in a later conversation. Onondaga County is in Climate Zone 5 under the Energy Conservation Construction Code of New York State 2025, which is what drives the insulation values, vapor retarder rules and unvented assembly rules that apply here, so a product specification written for a milder downstate zone does not transfer. And the consequence of getting it wrong is not only a gutter nuisance: the New York State Department of Health lists ice dams and insufficient attic ventilation among the moisture sources that cause mold growth in homes, which is the state's own health department connecting a roof detail to what ends up in the wall and ceiling cavity behind it.

Why March is worse than January, and when to book work

Syracuse normally receives 92.0 inches of snow between December and February and a further 21.9 inches from March to May. Eighteen of those inches normally fall in March, onto a roof that has been thawing and refreezing since December, which is why local ice dams tend to peak late in the season rather than at midwinter. A roof that has held up to the end of February has not yet been through the winter. The same numbers set the working season. With 34.0 inches of normal snowfall in January and 3.8 in April, a tear-off here is an April to November job, and a replacement booked for early spring is a replacement booked into snow. If a leak turns up in deep winter, the realistic sequence is to stabilize it, keep the interior damage down, and diagnose the roof properly once the deck can be seen.

What you can do without hiring anybody

Three things, and none of them is work anyone should be selling you. First, watch where the icicles form during the first thaw and photograph it. That is a map of where heat is leaving your house, and it is the most useful single thing you can hand to whoever eventually looks in the attic. Second, keep the valleys and the gutters clear before the first snow, because a blocked valley is where ice starts and a blocked gutter turns the eave into a trough. Third, deal with the water once it is off the roof. Syracuse averages 38.47 inches of total annual precipitation, so nearly forty inches of water a year has to leave through the gutters and leaders; undersized or disconnected downspouts are the reason a sound roof still produces a wet foundation. If what you find is insulation packed against the sheathing at the eaves and no clear intake, then the roof covering may not be your problem at all, and the money is better spent inside the attic than on the outside of it.