Calculator
Shed Snow Load Calculator (ASCE 7 Method, General Guidance)
Using the ASCE 7 method for an unheated, low-risk shed, the roof snow load is about 0.67 times the ground snow load before slope reduction. With a 30 psf ground snow load, an 8x10 shed roof carries about 20 psf, roughly 1,600 lb in total. Compare that with the snow rating your kit publishes, and confirm the ground snow load with your building department.
Snow load calculatorUpdates as you type
20 psf design roof snow load
- Roof slope
- 18.4°
- Flat-roof snow load pf
- 20.2 psf
- Slope factor Cs
- 1.00
- Design roof snow load
- 20.2 psf
- Total on 80 sq ft of roof plan
- 1,613 lb
General estimate only. It ignores drifting against a taller wall, which can multiply the load at the eave. Not engineering advice.
Sheds with published roof strength
Matched to this result, spread from budget to premium.
Prices change often; the button shows today's price on Amazon.
How the estimate is calculated
This uses the flat-roof snow load formula from ASCE 7, the standard US building codes reference: pf = 0.7 x Ce x Ct x Is x pg. For a detached storage shed we use Ce = 1.0 (partially exposed), Ct = 1.2 (unheated), and Is = 0.8 (Risk Category I, low hazard to people), so pf is about 0.67 times the ground snow load. A slope factor then reduces the load on steep roofs, sooner for smooth metal than for shingles or resin. For roofs under 15 degrees a code minimum load applies.
Ground snow load (pg) is set locally. Your building department publishes it, and the ASCE hazard tool gives it by address. Values range from 0 in the far south to well over 100 psf in mountain areas.
What the result does not include
- Drift. Snow piles up against a taller wall or where a shed sits beside a house, and drift loads can be several times the uniform load.
- Rain on snow and sliding snow from a higher roof onto the shed.
- The kit's actual strength. Some manufacturers publish a roof load rating and sell roof strengthening kits; many do not publish one at all.
Treat this as a screening number. If the estimate is near or above a published rating, plan to brush snow off after big storms or choose a stronger shed. It is not engineering advice.
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Frequently asked questions
How much snow can a resin shed hold?
It depends entirely on the model, and many resin kits do not publish a figure. Where a rating exists it is stated in pounds per square foot of roof. Compare that with this calculator’s design load for your area. If there is no rating, the safe habit in snowy regions is to clear the roof after heavy storms, especially on shallow-pitch resin roofs.
What is ground snow load?
Ground snow load is the weight of snow on the ground that has roughly a 2 percent chance of being exceeded in any year, in pounds per square foot. Building codes use it as the starting point for roof snow loads. Your local building department can tell you the value to use for your address.
Why is the roof load lower than the ground load?
Roofs lose snow to wind and, on heated buildings, to melting. ASCE 7 accounts for that with the 0.7 factor and exposure factors. An unheated shed gets a thermal factor above 1, which pushes the load back up, and low-risk storage buildings get an importance factor of 0.8.
This page is researched guidance, not professional engineering, legal or building-code advice. Sizes, loads and permit rules vary by product and by town: check your local code and the kit manufacturer's instructions before you build.