McCall averages around 140 inches of snow a year, and a heavy winter pushes that past 200. The design snow load in most of Valley County runs 90 to 120 pounds per square foot, depending on elevation and exposure, roughly three times what a Boise home gets designed for. Meeting the code number is table stakes. Designing a roof that performs (sheds predictably, doesn't ice-dam, and doesn't strip the siding off the gable wall when the drift slides) takes more than looking up a value in the IRC.
The load number is a minimum, not a target
The structural engineer will spec trusses or a stick-framed roof to meet the jurisdiction's ground snow load, reduced by exposure and thermal factors. That's the baseline. Where we routinely push beyond code is in rafter depth (for insulation, not for strength), in ridge beam sizing on cathedral ceilings, and in the connection details at valleys and roof-to-wall transitions. A roof fails at its transitions before it fails at a mid-span member, almost without exception.
Pitch, orientation, and where the snow goes
A 12:12 roof sheds aggressively. A 4:12 roof holds its snow all winter. Neither is wrong. They solve different problems. What you cannot do is design a roof that dumps snow onto a deck, a hot tub, a walkway, or the neighbor's driveway. We map snow-shed zones during design and make sure every piece of snow has somewhere to go that isn't someone's head.
- Entries get covered approaches protected from shed zones
- Decks sit where snow doesn't fall, or get designed to take the load
- Mechanical units, propane tanks, and generators get snow diverters
- Roof valleys that collect on the north side get ice-and-water underlayment all the way up
Ice dams are an insulation problem, not a roof problem
An ice dam forms when heat escaping through the ceiling melts snow at the warm part of the roof, water runs down, hits the cold eave, and refreezes. The fix is a ceiling that doesn't leak heat and an eave that stays cold. That means:
- R-60 or better in the ceiling, with no thermal bridging at the top plates
- Air-sealing the attic floor before insulation goes down
- A vented assembly that moves air from soffit to ridge, continuously
- Ice-and-water shield from the eave up at least 24 inches past the interior wall line
Unvented (hot roof) assemblies work too, and we use them on cathedral ceilings where venting isn't practical. But they have to be detailed carefully with closed-cell foam at the deck underside, not just loose-fill on top.
Snow retention where it matters
Snow guards, snow fences, and pad-style retention keep a metal roof from dumping all at once. Standing-seam metal is the default roof we spec in McCall: it sheds cleanly, lasts 40-plus years, and takes snow retention hardware without modification. We install snow retention above entries, above lower roof sections that would otherwise get hammered, and above anything you'd rather not replace.
Ventilation in a cold climate
A vented attic in McCall is a cold attic, and that's the point. If the attic is the same temperature as the outside air, snow on the roof doesn't melt from below. We size soffit and ridge vents per code minimums at minimum, and usually above, and we make sure bath fans and dryer vents exit through the wall or roof, never into the attic.
Valleys, dormers, and the little details
The places roofs leak and ice-dam in McCall are predictable: valleys, sidewall flashings where a dormer meets the main roof, chimney saddles, and any spot where a hot room sits under a cathedral ceiling. We detail these during design, not during framing, and we don't let the roofer freelance them in the field.
A roof in McCall is a system, not a surface. If you're early in planning a mountain home and want to talk through roof strategy, reach out.
