Awnings and Snow: How Much Weight Awnings Can Carry and How to Protect Them

Snow is the one weather condition that awnings are least designed for. A retractable awning must be fully closed before snow and never extended over it: its arms and brackets are built to hold fabric out, not to carry weight. A fixed fabric awning should have its fabric removed for the winter unless the frame was engineered for snow. A rigid aluminum, steel or polycarbonate awning can stay up, but only if its rated snow load (in pounds per square foot) meets or exceeds the design value your building department uses, with extra margin if it sits below a roof that can dump snow onto it.

This guide covers the load side of the problem: how heavy snow gets, how to compare a product's rating with your local requirement, the sliding-snow trap, and safe clearing. The step-by-step seasonal shutdown for retractables is in winterizing awnings.

How heavy snow gets

Snow weight depends on density, which varies more than most people expect:

FEMA's snow load safety guidance puts it in practical terms: roughly 10 to 12 inches of new snow, or about 3 to 5 inches of old, packed snow, weighs about 5 lb per square foot. Rain falling on existing snow is the worst case, because the snowpack soaks it up like a sponge and the load climbs without any visible change in depth.

For a retractable, even the low end is too much. The winterizing guide works through a 12 x 10 ft example: 4 inches of wet snow comes to roughly 600 to 800 lb across the canopy, far beyond what lateral arms and wall brackets are built to carry.

Which awnings can carry snow

The rigid materials themselves are compared in metal and polycarbonate awnings; this guide focuses on the snow rating behind them.

Reading a snow load rating

A snow rating is only meaningful if you compare it with the right local number. Design snow loads in the US come from ASCE 7, the structural loads standard referenced by the building codes, and are adopted and sometimes modified by states and local jurisdictions.

• Ground snow load is the starting point: the snow load on the ground that a site is expected to see on a statistical basis. It ranges from zero across much of the South to 30 to 50 psf or more in parts of the northern states, and much higher in mountain areas, where local "case study" values apply. ASCE's online Hazard Tool and your building department give the value for an address.
• Design roof snow load is what a structure must carry. It is derived from the ground load with factors for exposure (wind blowing snow off), heat from the building, slope and importance. An unheated awning gets no help from building heat.
• Drift and sliding surcharges are added for low roofs next to taller ones: precisely where an awning sits.

When shopping, ask for:

• The rated snow load in psf, and whether it is a live load allowance, a design load or an ultimate load (they are not interchangeable).
• The configuration it applies to: span, projection, post spacing, beam size and attachment method. A rating at 10 ft projection does not cover 13 ft.
• Engineering documentation: stamped calculations, an engineering letter or an evaluation report. Some patio cover manufacturers publish ICC-ES evaluation reports for their systems.
• Whether a permit is needed. Rigid covers and engineered awnings often require one in snow regions, and the building department will check the load. See awning permits and HOA rules.

The sliding-snow trap

Most snow failures of rigid awnings and door canopies do not come from snow that falls on them. They come from snow that slides onto them from the roof above, often all at once. A metal or slippery roof sheds snow readily, and any awning mounted under an eave is in its path.

Ways to reduce the risk:

• Install snow guards or snow retention on the roof above, especially on metal roofs.
• Mount the awning where the roof does not shed onto it (a gable end rather than under an eave), or specify a rating that includes sliding snow.
• Keep gutters clear; ice dams and gutter icicles break off in heavy chunks.
• Do not walk or park beneath a loaded canopy during thaws.

How to clear snow from an awning safely

1. Decide whether to clear at all. Light, dry snow on a rated rigid awning can be left. Clear when accumulation approaches about half the rated load, when rain is forecast on top of snow, or when you see deflection, creaking or cracking.
2. Work from outside the fall zone. Stand to the side of the awning, never beneath it or directly in front of the front edge, so a slide or collapse cannot land on you.
3. Use soft tools. A roof rake with a plastic blade or a soft-bristle broom on an extension pole. Metal shovels and ice chippers scratch powder coat, puncture fabric and crack polycarbonate.
4. Remove in layers from the outer edge. Pull snow toward the front edge in thin passes rather than levering big slabs. Leave a thin layer rather than scraping to the surface.
5. Leave ice alone. Do not chip ice or use open flame or heat guns. Calcium chloride and rock salt can corrode aluminum and fasteners; if you must melt, choose a product the manufacturer approves and rinse afterward.
6. Inspect after the thaw. Check for sag, bent members, loosened fasteners, cracked panels and sealant gaps at the wall.

If a retractable is caught out by snow

Surprise spring and fall storms do catch retractables extended, usually because a sun sensor or timer opened them. What to do depends on the amount:

• A dusting of dry snow: brush it off gently from the side with a soft broom, then retract. Extend again to dry on the next dry day.
• More than about an inch, or wet snow: do not retract with snow on the fabric; rolling it up overloads the motor or gearbox and traps water in the roll. Brush it off from the side in stages first. If the fabric is already bellied, stay out from under it and remove snow from the outer edge inward.
• Fabric frozen or iced: do not operate it. Wait for a thaw rather than forcing the motor, which can tear fabric or trip thermal protection repeatedly.

Afterward, inspect the arms for bends and the front bar for twist; a retractable that closes crooked after a snow event usually has a bent arm or shifted bracket. See awning arm replacement and awning sagging.

Choosing an awning for a snowy climate

• A retractable is a good choice if you only want shade from late spring to early fall and will close it for winter. Choose a full cassette so the rolled fabric is enclosed.
• A rigid cover is the better choice if you want year-round protection over a door, walkway or patio. Buy an engineered product with a rated snow load at or above your local design value, installed to the rated configuration, with a permit where required.
• Avoid fixed fabric awnings left up all winter, budget polycarbonate door canopies without a stated rating, and any awning placed directly under a roof that sheds snow.

For the full picture of weather limits by awning type, see awnings in bad weather.

Frequently asked questions

Can a retractable awning hold snow?

No. Retractable awnings are shade devices whose arms and brackets are not designed to carry snow, and manufacturers say never to leave them extended in snow. Even a few inches of wet snow on a 12 x 10 ft canopy can weigh several hundred pounds. Retract fully for the winter and switch off any sun sensor or timer that could open it.

How much snow can an aluminum awning hold?

Only as much as it is rated for, which varies widely with gauge, span, projection and support. Ask for the rated snow load in pounds per square foot for your exact configuration and compare it with your local design snow load from the building department. Around 10 to 12 inches of fresh snow is roughly 5 psf, but packed or wet snow is far heavier.

Should I remove snow from my awning?

Clear a rigid awning when accumulation approaches about half its rated load, when rain is forecast on snow, or if it sags, creaks or cracks. Work from the side with a plastic roof rake or soft broom, never from underneath, and remove snow in thin layers from the outer edge. Do not chip ice or climb onto the awning.

Do I need a snow-rated awning?

If the awning will stay out over winter where snow falls, yes. A rigid cover in a snow region should carry a documented rating at or above the local design snow load, and many building departments check this through a permit. If you will retract the awning or remove its fabric every winter, a snow rating is not needed.

Why did snow sliding off my roof damage the awning?

Snow sliding off a roof lands on an awning below all at once, adding weight that can be several times what fell directly on the awning, and it arrives as an impact. Metal roofs shed snow especially readily. Snow guards on the roof above, careful placement, or a rating that accounts for sliding snow reduce the risk.

Sources and further reading

• Federal Emergency Management Agency: Snow Load Safety Guide
• American Society of Civil Engineers: ASCE 7, Minimum Design Loads and Associated Criteria for Buildings and Other Structures, snow load provisions
• ASCE Hazard Tool (online ground snow load lookup by location)
• International Code Council: International Residential Code and International Building Code, structural design and snow load provisions
• ICC Evaluation Service: evaluation reports for patio cover and awning systems