Lake Ontario decides how a Rochester roof spends its winter. Lake-effect bands can drop a foot of snow on one side of Monroe County while the other side stays dry, and the load doesn't land evenly on a flat roof either. It piles against parapets, stacks up behind rooftop units and mechanical curbs, and drifts three or four feet deep in corners that never see the wind clear them. That's a very different loading pattern than the roof's design snow load, which assumes a uniform blanket, not a drift.
Drift loading versus design load
A roof engineered for a uniform snow load can still be overstressed locally by drift, and that's where structural distress shows up first — sagging deck between joists near a parapet, membrane stretched tight over a low spot, or a rooftop unit curb that's pulled at its seams. Insurance carriers want that distinction documented: is this a load problem from an unusual drift event, or is it a maintenance issue that predates the storm? We measure drift depth against the building's known snow load and photograph the affected structure and membrane before anything gets shoveled or melted away.
Ice dams and drain backups
The bigger claims driver most winters isn't the snow itself, it's what happens when it starts to melt. Rochester's freeze-thaw cycle means a warm afternoon can send meltwater toward a drain that refreezes solid overnight. Water backs up behind that ice, finds a seam, a flashing lap, or a parapet penetration, and gets under the membrane before anyone notices a stain inside. By the time a leak shows up on a ceiling tile, the ice dam that caused it may already be gone. We document drain and scupper conditions, ice buildup where it's still present, and the interior water path so the claim reflects an ice-related loss rather than "an unexplained leak."
Building stock plays into this too. Eastman-era industrial roofs and older downtown adaptive-reuse conversions often carry roof drains that were sized for a different era of maintenance, and a slow ice dam can sit undetected over a finished interior for weeks. Suburban office parks tend to have more rooftop equipment per square foot, which means more curbs and penetrations for drift to bank against. We walk each roof against its own drainage layout and equipment footprint rather than applying one snow-and-ice checklist to every building.
What we document after a snow or ice event
Dated photos of drift depth against parapets and curbs, drain and scupper condition, membrane distress in loaded areas, and any interior water damage tied to the roof. Where the load or the water path isn't obvious from the surface, we'll recommend a core cut or moisture scan so the extent of wet insulation is on record rather than guessed at. We also note whether existing flashing and coping details were adequate for the load, since a claim adjuster will often ask whether the damage points to a design gap versus storm intensity.
Repair sequencing in winter
Not every repair can happen the day the damage is found. Adhesives and sealants have temperature limits, and opening a membrane in January without a real plan for temporary dry-in creates a second problem on top of the first. We separate what needs immediate stabilization — tarping, temporary patching, drain clearing — from what should wait for a proper installation window, and we document that sequencing as part of the claim so a delayed permanent repair doesn't get mistaken for delayed damage.
We're your roofing contractor, not a public adjuster. We inspect, photograph, and measure the roof and hand you a documented scope you and your adjuster can work from — we don't file the claim or negotiate the settlement.
Buildings with older parapet details, undersized drains, or roofs that have already been recovered once tend to take the worst of a hard winter. If drift, ice, or a slow winter leak has you looking at a claim, the roof-side record needs to go down while the ice and the evidence are still there to see.
Frequently Asked Questions
Does commercial property insurance cover snow load damage?
Often yes, when the damage stems from an unusual drift or load event rather than long-term maintenance neglect. We document drift depth and structural distress so the cause is clear on the claim.
How do you document ice dam damage after the ice is gone?
Interior water staining, drain and scupper condition, membrane seam and flashing distress near where ice built up, and photos taken as soon as we're called all help establish the ice-related cause even after the ice itself has melted.
Can drift loading actually damage the roof structure?
Yes. Drift can concentrate several times the uniform design load in one area, which can stress the deck and structure locally even when the rest of the roof looks fine. We check loaded areas specifically, not the roof as a whole.
Should snow be removed before the roof is inspected for a claim?
Not before we've had a chance to document drift depth and pattern. Once snow is removed, that evidence is gone. We can advise on safe removal for roofs at real risk while still capturing the record first.
Is a slow winter leak treated differently than a sudden storm leak?
The documentation approach is the same — establish cause, extent, and timing — but a slow ice-dam leak often needs more interior evidence since the roof-level damage may not be visually dramatic.