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Snow Load Roof Calculator
Calculate roof design snow load using ASCE 7. Determine structural requirements by ground snow load and pitch with reinforcement cost estimates.
Educational calculators — always consult a licensed professional before making financial decisions.
Typical for mid-Atlantic, lower Midwest, and Pacific Northwest valleys. Minimal structural concern for modern roofs.
Snow accumulates readily. High roof snow load; flat roofs in snow country require engineered structural capacity.
Heat loss through ceiling melts bottom snow layer. Increases ice dam risk at eaves but reduces total snow weight.
Smaller footprint; total roof load is proportionally lower. Useful for estimating total pounds on structure.
Ensure adequate rafter sizing and periodic snow removal above 2 ft accumulation.
Snow load assessment
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Design snow load: 14 psf — Moderate category
Based on ASCE 7 simplified snow load calculation. For structural design decisions, always consult a licensed structural engineer with local knowledge.
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How it works
Enter location
Select your climate zone or enter the ground snow load (Pg) from ASCE 7 maps.
Input roof parameters
Set roof slope, exposure category, thermal condition, and occupancy type.
Get design snow load
Receive the flat roof snow load (Pf) and sloped roof load (Ps) per ASCE 7 methodology.
Frequently Asked Questions
How do you calculate roof snow load?+
Use the ASCE 7 formula: Ps = 0.7 × Cs × Is × Pg. Where Ps is the sloped roof snow load, Cs is the roof slope factor (decreases as pitch increases above 5/12), Is is the importance factor (1.0 for residential), and Pg is the ground snow load for your location. A roof with 6/12 pitch in a 40 psf ground snow load area has a design load of approximately 20–28 psf.
What is the maximum snow load a residential roof can handle?+
Most residential roofs are designed for 20–40 psf (pounds per square foot) of snow load depending on local codes. Fresh snow weighs 3–7 lbs per sq ft per inch of depth. Wet, packed snow weighs 20+ lbs per sq ft. If snow accumulation reaches 2–3 feet of wet snow, it can exceed the design load on roofs in high-snow areas. Consult a structural engineer if you are concerned about your roof's capacity.
Should I remove snow from my roof?+
Remove roof snow if accumulation exceeds your roof's design load, if you hear cracking sounds, see visible sagging, or notice doors and windows sticking (indicating structural stress). Use a roof rake from the ground — never walk on a snow-covered roof. Remove snow in sections from the edge upward. Ice dams (ice buildup at eaves) are a separate concern and require professional removal.
How do steep roofs handle snow better than flat roofs?+
Steeper roofs shed snow more readily due to gravity — pitches above 6/12 self-clear much more effectively than low slopes. ASCE 7 allows snow load reductions for roofs above 5/12 pitch. Flat roofs (under 2/12) require the full ground snow load in design calculations and need careful drainage for snowmelt. Metal and smooth surfaces shed snow better than textured materials.
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Back to the calculator ↑Snow Load Roof Calculator is built and maintained by the RealCostIQ editorial team. Cost ranges and rates are checked against published industry data and contractor quotes, and revised when the underlying figures move. Read our data methodology or more about who builds this. Every calculation runs in your browser — no account, and none of your inputs are stored.
Cost ranges and rates here are checked against contractor quotes and published industry data. If a number still looks off, email Support@RealCostIQ.com and we'll review and fix it.