Four seasons on one roof
Boise roofs deal with hot, dry summers and cold winters with snow. The National Weather Service describes the climate as semi-arid, with around 20 inches of snow in an average year, and summer heat that has reached 111°F. NOAA's engineering weather data for Boise records an average of about 78 freeze-thaw cycles a year. That combination means roofing materials expand and contract repeatedly, sealants dry out in summer, and water that gets into a small gap in winter freezes and widens it.
Snow load and structure
The City of Boise's residential design criteria use a 20 psf ground snow load. Most homes are designed for it, but problems arise when a heavier roofing material is installed on a structure built for a lighter one, or when an addition or patio cover is built without accounting for drifting snow against a taller wall. If you're changing roofing materials or adding a roof, ask the contractor whether the structure needs to be checked and whether a permit is required.
Ice dams
When attic heat melts snow on the upper roof, the water can refreeze at the eaves and form an ice dam, forcing water under shingles. In Boise, ice dams usually point to inadequate attic insulation or ventilation, or to heat leaking from recessed lights, ductwork or bathroom fans in the attic. Ice and water barrier along the eaves protects against leaks, but the lasting fix is in the attic. Ask the roofer to inspect the attic as part of any estimate.
Summer sun
Boise's dry summers are hard on asphalt shingles, especially on south- and west-facing slopes. Look for curling, cracking and granule loss on those slopes first. Good ventilation helps keep attic temperatures down and extends shingle life.
Gutters
Gutters in Boise need to handle both summer storms and winter snowmelt. Clogged gutters can freeze solid in winter and add to ice buildup at the eaves. Clean them in fall after leaves drop, and make sure downspouts carry water away from the foundation. Heated cables are sometimes used in problem spots; ask the contractor about safe installation and operating costs.
Before you hire
Ask Boise roofers how they'll handle ice and water barrier, attic ventilation and any structural questions about snow load. Ask about the permit, the schedule and what the workmanship warranty covers, and get it in writing.
Planning a replacement
The best time to replace a roof in Boise is usually late spring through early fall, when temperatures let shingles seal properly. Book early, because roofers' schedules fill after storm seasons.