Step 1: Confirm the Design Snow Load for the Property
Snow load requirements in Salt Lake City vary by elevation and location. The base requirement for valley locations is 30 pounds per square foot. Foothill neighborhoods like Federal Heights, Olympus Cove, and parts of Cottonwood Heights typically require 40 to 60 pounds per square foot. Mountain locations require 80 or more.
Look up the property's design snow load by checking Salt Lake County's ground snow load map or asking the city building department. The International Residential Code referenced by the International Code Council sets the framework, and Salt Lake County publishes local amendments with elevation-adjusted values.
This step takes ten minutes and tells you what the roof was supposed to be designed for. The next steps verify whether it actually was.
Step 2: Inspect Rafter Sizing and Spacing
Go into the attic with a flashlight, a tape measure, and a notebook. Measure rafter dimensions and spacing. Typical residential rafters in Salt Lake City foothill homes should be 2x10 or 2x12 spaced 16 inches on center for spans of 12 feet or longer. Smaller dimensions or wider spacing may indicate the original framing is undersized for current snow loads.
Check for sag in the rafters by sighting along the bottom edge. A roof that has been carrying loads for decades will show some deflection. More than a half inch of sag over a 12-foot span warrants further evaluation by a structural engineer.
Look at the ridge board and any collar ties. Cracked rafters, split ridge boards, or pulled connections at the ridge indicate the framing has already moved under load.
Step 3: Evaluate the Attic for Ice Damming Risk
Ice dams form when warm air leaks from the living space into the attic, melts snow on the roof, and the meltwater refreezes at the cold eaves. The dam then backs water up under the shingles. This is one of the most common winter damage patterns in Salt Lake City homes.
Check Attic Insulation
Insulation depth should be R-49 or higher in Salt Lake City. That translates to roughly 16 inches of blown cellulose or 18 inches of blown fiberglass. Compressed insulation, missing sections near the eaves, or visible bare framing all indicate inadequate insulation. The U.S. Department of Energy publishes climate zone insulation guidelines that align with these targets.
Check Air Sealing
Look for gaps around recessed lights, exhaust fans, attic hatches, and electrical penetrations. Warm air escaping through these openings drives ice dam formation more than insulation depth alone. Properly air-sealed homes with moderate insulation often outperform poorly sealed homes with thick insulation.
Check Ventilation
Soffit and ridge vents work together to flush warm air out of the attic. Blocked soffit vents are a chronic problem in Salt Lake City because installers often cover them with insulation. Look for baffles at the eaves that hold insulation back from the vents.
Step 4: Inspect the Roof Surface from Outside
From the ground or with a ladder reaching the eaves, look for signs of past snow load stress and ice dam damage. Curled or lifted shingles near the eaves, missing shingle tabs, exposed underlayment, and damaged drip edge all suggest ice damming has occurred. Check for staining on the underside of soffit boards.
If the roof has metal flashings at valleys and walls, inspect them for separation or buckling. Snow accumulation in valleys creates concentrated loads that distort flashings over time.
Step 5: Look for Snow Guards and Other Hardware
Snow guards prevent dangerous slides of accumulated snow off metal or steep-slope roofs. Homes in the foothills with metal roofs should have snow guards installed above entries, walkways, and parking areas. The absence of snow guards on a metal roof above a sidewalk is a safety concern, not a structural one, but it should be on your list.
Also check for heat cables along eaves. These are common in older homes as a retrofit for chronic ice damming. Their presence is a clue that the home has had ice dam problems in the past. Functional heat cables are not a problem, but they are not a substitute for proper insulation and ventilation.
Step 6: Ask About the Roof's History
Request maintenance records from the seller. Ask specifically about ice dam repairs, leak repairs, and any roof framing modifications. A homeowner who has been actively managing ice dam risk will usually have documentation. A homeowner who shrugs at the question may have been ignoring the issue.
If the home is older than 30 years and there is no record of insulation upgrades or framing reinforcement, plan to budget for both. Insulation and air sealing improvements run $2,500 to $6,000 for a typical Salt Lake City home. Structural reinforcement of undersized rafters, when needed, runs $5,000 to $20,000 depending on scope.
What Derek Did After the Fact
Derek hired a structural engineer who confirmed his rafters were undersized for his elevation. He added sister rafters alongside the existing ones for $12,000, blew in additional insulation to bring the attic to R-60, and installed proper soffit baffles. The next winter went without incident. He told me the work cost less than he expected and the house was noticeably warmer.
The inspection process above would have flagged the issues before closing and given him leverage to negotiate. It is a few hours of careful evaluation that can save tens of thousands of dollars in winter repairs.