A roof going up near Rankin Inlet, Nunavut is built against two stacked numbers: 3.0 kPa of ground snow and another 0.2 kPa of rain load sitting on top of that snow, before the code’s conversion factors even touch it. Neither figure alone is what a truss gets built for, and neither tells you what your own roof was actually designed to hold. Pull the plan review file at your municipal building department, or ask the engineer of record, before assuming last year’s roof matches this year’s table.
What is the ground snow load in Nunavut?
The ground snow load used for design work at Rankin Inlet, Nunavut is 3.0 kPa, with an additional 0.2 kPa of rain load counted on top of it, according to the National Building Code of Canada 2020, Appendix C, Table C-2. That pairing matters. The table does not give a bare snow number anywhere in the territory, because rain falling onto standing snow adds real weight that the design has to account for separately from the snow itself.
Ground load is not roof load
This figure describes the snow sitting on open, level ground around Rankin Inlet, not the load a rafter actually carries. The ground figure is not the roof figure: the code runs that ground number through a set of factors, covered in the next section, before it becomes the specified roof snow load an engineer stamps on a drawing. Treating the two as the same thing is the single most common mistake in reading this table, and it can understate or overstate the true roof number depending on which factor gets skipped.
Who actually uses this number
A builder pulling a permit in Rankin Inlet, or an engineer producing truss drawings for a house or a commercial building there, starts from this same Table C-2 row. It is also the figure a plan reviewer checks against when a homeowner submits drawings for a garage, an addition, or a re-roof that changes the structure. Other communities across Nunavut carry their own rows in the same table, and a figure taken from Rankin Inlet does not automatically apply in Iqaluit or Cambridge Bay. Confirm the value for your own community with your municipal building department before ordering trusses. Getting this number wrong at the permit stage is not a paperwork error: it changes the size of the members an engineer specifies and the connections a builder orders, and a mistake here is expensive to fix once the trusses are already on site.
How much snow can a roof hold in Nunavut?
There is no single number for this, and anyone who gives you one is guessing. What a roof near Rankin Inlet actually carries depends on the ground figure, the roof’s own shape, and where snow has been allowed to pile up against something taller.
From ground load to roof load
The code takes the ground value of 3.0 kPa plus the 0.2 kPa rain load and runs it through a formula that includes a basic factor, an exposure factor, a slope factor and an accumulation factor before it becomes the specified roof snow load. For an ordinary heated house roof with a normal slope, that basic factor typically pulls the number down to somewhere around seven-tenths of the ground value. A steep roof pulls it down further, since snow slides off before it can pile up. None of that reduction applies where snow drifts.
Drift is where roofs actually fail
Drifting is the part of this formula that raises the number instead of lowering it, and it is also where roof failures actually happen. Snow blown off a taller section of roof, or off an adjacent building, piles up against a wall, below a dormer, or in a valley between two roof planes, and an accumulation factor accounts for that pile being far deeper than the open snow around it. A flat-looking roof next to a two-storey wall is exactly the geometry that produces a local load well above the number that applies to the open field beside it.
Depth is not the same as weight
A foot of fresh snow in January is a fraction of the weight of a foot of wet snow in April, and that difference is what actually matters to a rafter. Fresh, dry snow is mostly air, light enough that a deep layer can still be a modest load. Settled or wet snow packs down to two or three times that density, and a crust of ice on top of either is heavier again. That is why a roof that shed a heavy January snowfall without trouble can still be pushed past its limit by a smaller, wetter spring snowfall sitting on top of an existing base.
Signs a roof is carrying too much
- Interior doors that suddenly stick or won’t latch
- New cracks running across ceiling drywall or at wall-ceiling joints
- A ridge line that looks like it’s dipping when viewed from the street
- Creaking or popping sounds from the attic under load
Any of those is a reason to get snow off the roof from the ground, with a roof rake, rather than climbing onto a loaded roof to shovel it. A roof already carrying more than it should is not a safe place to add a person’s weight, and raking from the ground removes load without adding any. If you’re planning the roofing work itself rather than just managing a heavy winter, the basics of roofing decisions are worth understanding before comparing materials.
What wind speed must a roof withstand in Nunavut?
The reference wind pressure used for structural design at Rankin Inlet, Nunavut is 0.6 kPa, for the 1-in-50-year return period set out in the National Building Code of Canada 2020, Appendix C, Table C-2, and that same table is what NBC Part 4 and Part 9 draw on for the strength calculations behind a roof’s connections. This is an hourly wind pressure, not a gust speed, and it is not a number you can line up against a forecast’s wind speed or against an American gust-speed figure. The two measure different things on different bases, and there is no honest conversion between them.
Two return periods, two different jobs
The same table also carries a 1-in-10-year value of 0.47 kPa for Rankin Inlet. That lower figure is for serviceability, things like how much a wall assembly is allowed to deflect or how much cladding is expected to flex in an ordinary storm, and it plays no role in the strength calculation. The 0.6 kPa figure is the one that governs how a roof is actually fastened down.
What the pressure actually buys
That number drives decisions that don’t show up until something goes wrong: the wind rating on the shingles themselves, the nailing pattern used to fasten them, how the sheathing is fastened to the trusses, and the uplift connections tying the roof structure back down to the walls. Roofs rarely fail in the middle of a slope. They fail at the edges, the rakes and the ridge, because that is where wind pressure concentrates and pulls hardest at whatever is holding the roof down. A roof built to withstand this pressure needs those connection details right, not just a shingle rated for wind.
Nunavut is not the only territory working from figures this far north. Rankin Inlet’s neighbours in the Northwest Territories run their own snow load and wind rules, drawn from their own reference stations, and the two are not interchangeable even though both sit far up the same climate zone system.
Does Nunavut require an ice barrier under the shingles?
An ice barrier is a self-adhering waterproof membrane installed under the shingles, run up from the eave edge past the point where the wall below is heated, usually described as past the interior wall line. Its job has nothing to do with stopping snow from building up. It stops meltwater that has backed up behind an ice dam from working its way under the shingles and into the roof deck.
What actually causes an ice dam
Ice dams form because heat leaking out of the living space into the attic warms the underside of the roof deck enough to melt the bottom layer of snow sitting on it. That meltwater runs down the slope until it reaches the cold overhang past the heated wall, where it refreezes, and the ice builds into a dam that backs standing water up under the shingles above it. Rankin Inlet’s coldest month has a mean daily minimum of about -34.3°C, according to Environment and Climate Change Canada’s 1981-2010 climate normals for the Rankin Inlet reference station, and a season that cold combined with the 3.0 kPa ground snow load already established for the area is exactly the kind of pairing that drives long, hard freeze-thaw cycling at the eaves once a house is heated. The membrane addresses the symptom. Only air sealing the attic floor and insulating to a level suited to this climate actually stops the dam from forming in the first place, and Rankin Inlet’s heating degree-days put the area in Natural Resources Canada’s climate zone 8, the most demanding of NRCan’s insulation zones.
What the code says, and where to check
The code that applies in Nunavut is the Building Code Regulations (R-009-2018), made under the territory’s Building Code Act and derived from the 2015 edition of the National Building Code of Canada rather than the 2020 edition. It is administered by the Department of Community and Government Services, Office of the Fire Marshal. That regulation is static, meaning Nunavut does not pick up national code updates automatically the way a rolling adoption would, so a rule introduced only in the 2020 national code does not apply here unless the territorial regulation has been separately amended to add it. Ask the Office of the Fire Marshal or your municipal building department directly whether an ice barrier membrane is required for your roof and under what conditions. Don’t assume an answer either way just from the climate.
What roofing material suits Nunavut best?
There is no single best material here, only trade-offs that play out differently against Rankin Inlet’s 3.0 kPa ground snow load and 0.6 kPa wind pressure than they would somewhere with a lighter snow load or calmer wind.
Comparing the categories
| Material | Behavior under snow load | Behavior under wind |
|---|---|---|
| Architectural asphalt shingles | Adds negligible dead weight of its own, snow tends to stay put rather than shed | Wind rating depends on the specific product and the nailing pattern used |
| Standing-seam metal | Sheds accumulated snow readily, which shifts the load problem to wherever it lands | Performs well when panels and clips are fastened to spec, poorly when they aren’t |
| Slate or concrete tile | Its own dead weight adds directly to whatever snow load the structure must already carry | Heavy enough that uplift is rarely the dominant concern, fastening still is |
Where the snow goes matters as much as what’s on top
A metal roof that sheds its snow load quickly is solving one problem and creating another. A slab of snow and ice releasing from a roof edge above a doorway, a walkway or a driveway is a hazard, and deciding where that release happens, with snow guards, roof geometry or simply what sits below the eave, is part of specifying the roof, not an afterthought. Slate and concrete tile take the opposite approach: they add their own weight to the design load rather than shedding it, so the structure underneath has to be sized for the tile as well as for the snow sitting on it.
Fastening decides more than the material label does
Where wind governs the design, how a roof covering is attached to the deck matters more than which material was chosen. A shingle rated for high wind performs to a lower standard if it’s nailed with the wrong pattern or fewer fasteners than specified, and a metal panel system is only as good as the clips holding it down. This same trade-off, matching a covering and its fastening to a locally specific snow and wind figure, gets worked out at building departments in very different climates. A homeowner in Rankin Inlet and one checking the Delaware’s roof snow load and wind rules are answering the same category of question with entirely different numbers behind it.