Burlington’s building permits run on a ground snow load of 40 psf, the figure a truss drawing has to answer to before a plan reviewer signs off. That number is only the start of the conversion that actually decides what a roof frame must carry, and it comes from a reference city, not from the state as a whole. Before you assume anything about your own roof, find out whether your town has even adopted a building code, because in Vermont that decision sits with the municipality, not the state.
What is the ground snow load in Vermont?
The design ground snow load at Burlington, Vermont is 40 psf under ASCE 7-16, the edition that IRC/IBC 2021 makes applicable in most states. That figure is what shows up on a permit application, gets checked in a plan review, and ends up as a line item on the truss drawings a builder orders from a truss plant. It is not, on its own, the load your roof deck has to resist.
Ground snow load is measured on open, level ground. A roof is not open, level ground, so the code applies exposure, thermal and slope factors before the number means anything structurally. For an ordinary heated sloped house roof, that conversion brings Burlington’s 40 psf ground value down to roughly 28 psf of roof snow load, and a steeper roof pulls it lower still because snow slides off before it can pile up. This is the gap that trips up more homeowners than any other detail on this subject: the number on the map and the number on the rafter are not the same thing.
A newer edition, ASCE 7-22, maps the same point at 78 psf. That is not more snow falling on Burlington and it is not a sign that existing roofs are suddenly undersized. The two editions use different math: 7-16 is a nominal value paired with a 1.6 load factor, while 7-22 is a strength-level value paired with a 1.0 load factor. A few jurisdictions are beginning to adopt 7-22, but the figure your current permit uses is the 7-16 one.
The mountainous part of Vermont is treated differently again. It falls inside a CS, or case-study, region, which means the national map assigns it no value at all. A site-specific snow study, not a map lookup, is what a project at elevation needs. If you’re building or re-roofing above the valley floor, that study, not the Burlington figure, is the number that belongs on your drawings.
How much snow can a roof hold in Vermont?
There is no single number for this, and any page that gives you one is guessing. What you can work from is the same 40 psf ground figure measured at Burlington, converted the same way: roughly 0.7 of the ground value for an ordinary sloped, heated roof, and less on a steep one. That gets you a design load, not a failure point, and it says nothing about drift.
Where drift changes the picture
Drift is where roofs actually get into trouble. Snow does not sit evenly across a roof plane. Wind moves it, and it piles up against a parapet or a taller adjoining wall, below a dormer, in a valley between two roof planes, and on a lower roof next to a taller structure. Those spots can carry several times the load of open roof area a few feet away, and they are exactly the spots a design has to account for separately from the flat ground figure.
Depth is also a poor guide to weight, which is the part most people get wrong when they eye a snow load from the ground. Freshly fallen, light snow runs around 5 to 7 pounds per square foot for every foot of depth. Once that snow settles, or once it takes on rain or thaws and refreezes, the same depth can weigh two to three times as much. A layer of ice on top adds more again. That is why a foot of snow sitting since a January storm is a very different load than a foot that fell last week in March and has already gone through a freeze-thaw cycle.
Watch for these signs that a roof is carrying more than it should:
- Interior doors that start sticking or no longer latch properly
- New cracks or a spreading crack in ceiling drywall
- A ridge line that looks like it is sagging when viewed from the street
- Popping or cracking sounds from the attic framing under load
If you see any of that, raking snow from the ground with a roof rake is the safe response. Climbing onto a loaded roof to shovel it is not, and it is also the single most common way people get hurt dealing with this problem. Anyone unsure whether a roof is carrying too much should call their building department or a licensed engineer rather than guess from the ground.
What wind speed must a roof withstand in Vermont?
The basic design wind speed at Burlington, Vermont is 107 mph under ASCE 7-16, for Risk Category II, the category that covers ordinary houses. That number is a 3-second gust measured at 33 feet in open terrain, known as Exposure C. It is not a sustained wind, not a record gust, and not what a weather forecast means when it announces a wind speed. Comparing it directly to a hurricane’s headline number will make the code look absurdly weak, when it is measuring something different.
ASCE 7-22 maps this same location at 107 mph as well, so there is no disagreement between the two editions here, unlike some parts of the wind map where the newer edition moved the number up or down.
What the number actually governs
This figure feeds directly into shingle wind ratings, nailing patterns, sheathing fastening schedules, and the uplift connections tying the roof framing down to the walls. Edges, rakes and ridges are where uplift concentrates in a wind event, which is why those areas get tighter fastening schedules than the field of the roof. A shingle with a good wind rating still fails at those edges if it was installed to a looser pattern than its rating assumes.
Coastal states carry a very different problem alongside their wind numbers. Along the Gulf, for instance, our page on Mississippi’s roof snow load and wind rules covers wind-borne debris regions where the code requires impact-rated glazing or shutters. Inland Vermont is a different kind of wind problem: uplift and fastening, not flying debris.
Does Vermont require an ice barrier under the shingles?
An ice barrier is a self-adhering membrane run along the eave, up past the point where the interior wall line sits below the roof. It doesn’t stop snow from sitting on the roof. It stops the meltwater that backs up behind an ice dam from reaching the roof deck once regular shingles alone can no longer keep it out.
Whether ice dams are a real risk here
Burlington’s coldest-month mean daily minimum runs 12.9°F, per NOAA’s 1991-2020 climate normals. Combined with a ground snow load of 40 psf at the same station, that is a long, cold winter with plenty of snow sitting on roofs for weeks at a time, which is exactly the combination that builds ice dams. The mechanism is straightforward: heat escaping from a warm attic melts the snow on the roof from underneath, that meltwater runs down until it hits the colder overhang past the exterior wall, and it refreezes there, building a dam that backs water up under the shingles above it.
That points to a real risk in this climate, but it does not settle whether a membrane is legally required on your project. Vermont has no statewide residential building code. No state agency administers one. The Division of Fire Safety runs a fire and building safety code, but it applies to public buildings, and owner-occupied single-family homes are specifically excluded from that definition. The Department of Public Service administers the Residential Building Energy Standards, which apply statewide, but that is an energy code, not the section of a building code that would mandate an ice barrier detail. Whether a code requiring one applies to your project is decided locally, town by town, so check with your municipal building department before assuming either way.
Whatever the local rule says, the membrane only treats the symptom. It protects the deck once an ice dam has already formed. The actual fix is stopping the attic heat loss that melts the snow in the first place, through air sealing and adequate attic insulation, the same problem cold-climate states wrestle with everywhere from Vermont to Minnesota, where our page on Minnesota’s roof snow load and wind rules walks through the same mechanism. A roof with a membrane and a leaky attic still grows ice dams. It just doesn’t leak into the house while doing it.
What roofing material suits Vermont best?
The honest answer depends on what you’re optimizing for, because Burlington’s 40 psf ground snow load, its 107 mph design wind speed, and the state’s single IECC climate zone of 6A each push in a slightly different direction. Vermont has that one zone everywhere, with no county exceptions, which is a rare convenience: nobody in this state has to look up which zone they fall into before checking an insulation table.
| Material | Snow behavior | Wind consideration | Added dead load |
|---|---|---|---|
| Architectural asphalt shingles | Holds snow in place, sheds gradually | Wind rating depends on nailing pattern matching the rating | Low |
| Standing-seam metal | Sheds snow quickly, often in one slide | Panel and clip fastening carries the uplift load at seams | Low |
| Slate or concrete tile | Holds snow well due to weight and surface texture | Individual units can be more vulnerable at edges if not properly fastened | High, adds to the snow load the structure already carries |
Standing-seam metal is worth a second look here because it sheds snow efficiently, which sounds like an advantage until that snow slides off in one sheet. Where it lands matters: over a doorway, a walkway or a driveway is a design decision that needs snow guards or a planned clear zone, not something to discover the first time it happens.
Slate and concrete tile add their own dead weight on top of whatever snow load the roof is already carrying, so a structure has to be designed or verified for that combined load, not just the snow load alone. Fastening and underlayment matter more than the material itself once wind is the governing concern: a shingle rated for high wind performs to whatever nailing pattern it was actually installed with, not to the rating printed on the wrapper. For a broader look at how roofing choices interact with climate and structure before narrowing to any one material, see our general guide to Roofing.