Carport & Patio Cover Snow Load Calculator
Carports, patio covers and open shelters are unheated, open-air structures, so they use the higher thermal factor Ct = 1.2: the snow on them does not get any help melting from below.
The worksheet
ASCE 7-22The balanced load of 25.2 psf governs (it exceeds the 20 psf minimum).
≈ 37,800 lb total on 1,500 sq ft of roof plan
Flat-roof load Pf = 0.7 × Ce(1) × Ct(1.2) × Is(1) × Pg(30) = 25.2 psf. Sloped-roof balanced load Ps = Cs(1) × Pf = 25.2 psf.
| Ground snow load, Pg | 30 psf | site input |
| Exposure factor, Ce | 1 | Table 7.3-1 |
| Thermal factor, Ct | 1.2 | Table 7.3-2 |
| Importance factor, Is | 1 | Table 1.5-2 |
| Slope factor, Cs | 1 | Fig. 7.4-1 |
| Snow density, γ | 17.9 pcf | Eq. 7.7-1 |
| Settled depth at design load | 17 in | design ÷ density |
- 01Estimated snow density ≈ 17.9 pcf, so 25.2 psf is roughly 17 in of settled snow.
- 02At roof steps, parapets and against walls check drift loads (§7.7) with the drift calculator, and check sliding snow (§7.9) where this roof sheds onto a lower roof, walk or equipment.
- 03Ground snow load Pg is set by your local building department / the ASCE 7 Hazard Tool. Always confirm the value for your exact site before you build or submit.
Carports & patio covers rated for your snow zone
Your design roof snow load is 25.2 psf. Light big-box covers are often rated for only 10 to 20 psf. Match the kit's rated load to the design load above before you buy, or get a quote for a heavier steel structure.
Get matched with a certified steel carport supplier rated for your snow loadFree, no obligation. We pass your numbers to suppliers so quotes come back accurate.Bolt-together steel carports and patio covers. Check the spec sheet's rated snow load against your number.
Shop carport kitsMid-weight metal carports and canopies, often with a stated snow-load rating in the spec sheet.
Browse VEVOR carportsSome links are affiliate links: if you buy through them we may earn a commission at no extra cost to you. These are starting points, not engineering endorsements. Always confirm a product's rated snow load meets the design load above.
Notes for carport / patio cover roofs
- Many big-box carport and patio-cover kits are rated for a fixed snow load (often 10–30 psf). Compare that to your calculated design load before buying.
- A low-slope cover in a snowy area can easily exceed a light kit's rating, so upgrade the gauge or add posts/purlins.
Notes & questions
01How much snow can a carport hold?+
Check the kit's rated snow load on its spec sheet, then compare it to the ASCE 7 design load for your site from this calculator. If the design load is higher, the kit needs upgrading or more support.
02What snow load rating do I need for a patio cover?+
At least the ASCE 7 design roof snow load for your location, computed with the unheated thermal factor (Ct = 1.2). Enter your ground snow load above to see the number.