ASCE 7-22 · IRC 2021 · NM amendment

Snow load calculator for NM mountain homes.

Standard NM code (Albuquerque, Santa Fe) assumes 30 psf ground snow. Taos, Los Alamos, Ruidoso, and Cloudcroft demand 55–120 psf. Wrong assumption = collapsed carports and cracked trusses.

Your building
Design snow load

Taos · 6:12 · asphalt

Ground snow (pg)
55 psf

Per ASCE 7-22 Fig 7.2-1 for this elevation. NM amendment values.

Flat-roof snow (pf)
38.5 psf

0.7 × Ce 1 × Ct 1 × Is 1 × pg 55

Sloped-roof snow (ps)
38.5 psf

Slope factor Cs = 1.00 for asphalt at 6:12.

Drift surcharge
None

No upper roof adjacent.

Total design load
38.5 psf

Use for truss and rafter sizing. Multiply by tributary area for member loads.

Rule of thumb: if your neighborhood is above 7,500 ft and your existing carport or porch was built to Albuquerque code (30 psf), it is under-designed by 2–3× for a Cloudcroft or Angel Fire winter. Retrofit before the next big storm.

Common mountain failures

What we see after a big snow year.

Metal roof avalanche

Slick metal + heated attic + 8:12 pitch = 400 lb of snow sliding onto the car below. Fix: snow guards in a diamond pattern above every door and driveway.

Drift-crushed porch

3-ft drift lands on 30-psf porch. Trusses split at the heel. Fix: engineer verifies drift zone; add posts or size for full drift.

Ice dam through the eaves

Warm attic melts underside, refreezes at cold eave, water backs up under shingles. Fix: 24-inch minimum ice-and-water shield + air-seal + insulate to R-60.

Next step

Building or re-roofing above 7,000 ft? Free snow-load review — (505) 595-7203.

Book the free on-site inspection, or send a photo and we'll tell you what to do next. No sales pitch — we don't install roofs.