Snow load and roof collapse in Vermont buildings

Why weight and depth are not the same thing

Dry powder and saturated snow of the same depth are very different loads. Snow that has absorbed rain, or that has gone through repeated melt and refreeze, is dense in a way that eye-level depth completely disguises.

The sequence that produces most problems in this region is accumulation followed by a rain event or a warm spell — the snow does not leave, it gets heavier, and it can pick up meltwater from above and hold it.

The warning signs that matter

Structural distress shows up in ways people usually attribute to something else. Interior doors that suddenly stick or will not latch. Windows that jam. New cracks in ceilings, in drywall at wall-ceiling junctions, or in masonry. A visible sag or dip in a ceiling line. Creaking, popping or cracking sounds. Sprinkler heads dropping below ceiling level in a commercial building.

Any of these appearing during or after a heavy snow period is a reason to leave the affected area and get an assessment, not a reason to wait and see whether it gets worse.

• Doors or windows that suddenly stick or will not latch
• New cracks in ceilings, drywall junctions or masonry
• A visible sag or dip in a ceiling or roof line
• Creaking, popping or cracking noises
• Sprinkler heads or ceiling fixtures dropping below the ceiling
• Doors frames or partitions bowing

Which roofs carry the most risk

Low-slope and flat roofs hold snow rather than shedding it, and they also collect drifted snow at parapets and against higher walls. Long-span structures — barns, warehouses, arenas, older agricultural buildings — have less redundancy than a house roof.

Roof geometry matters as much as pitch. Valleys, the low side of a change in roof height, and areas behind dormers all collect drift, and a drift load is concentrated where the structure was not designed for a concentrated load.

Removing snow from a roof

Roof rakes used from the ground reduce load at the eave without anyone leaving the ground, and that is the version of this most property owners should be doing. Getting on a snow-covered roof in winter is how people are seriously injured.

Where a roof genuinely needs clearing, it is done by people equipped for it, and it is done evenly. Clearing one side of a roof completely and leaving the other loaded creates an unbalanced load, which is its own problem.

After a partial or full collapse

Nobody re-enters until the structure has been assessed. A partial collapse redistributes load through elements that were not designed to carry it, and the second failure frequently follows the first by hours rather than by seconds.

Once it is safe, the building is treated as an open-envelope loss: temporary protection, then the interior water work as snow melts into the structure, then the structural repair. All three are usually running at once.

The water loss inside a collapse

A collapsed or breached roof puts snow into the building, and snow becomes water on a delay. Insulation, ceilings, framing and contents all take on moisture over the following days rather than immediately.

That is why a snow-related structural loss is scoped as a water loss too, with extraction, removal of saturated material and verified structural drying, rather than as a repair job with some cleanup attached.

Snow load across the Greater Burlington region

The load varies significantly across a short distance here. The upland towns — Underhill, Jericho, Hinesburg, Cambridge and Jeffersonville — carry substantially more snow, hold it longer and see later melts than the lakeshore municipalities, so their exposure window runs further into the year.

Lake Champlain moderates the immediate shoreline in Burlington, South Burlington, Shelburne, Charlotte and Colchester, which usually means less accumulation but more of the melt-and-refreeze cycling that adds density to what is there.

The building stock matters as much as the geography. This region has a large number of older agricultural buildings, long-span barns and low-slope commercial roofs, and those are the structures where a heavy year shows up first.