Outdoor

How much snow can a roof hold?

By Roof & Router Team. Updated October 19, 2026.

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How much snow can a roof hold?

There is no single answer, because every roof is built for a design snow load set by the building code where you live. That load is given in pounds per square foot (psf). Here are some published figures:

So a house in a snowy northern state is usually built for far more snow than one in a mild climate. To learn what your house was built for, ask your local building department. Montana’s code office also points people to the ASCE 7 Hazard Tool, which looks up design snow loads for a location. A contractor or engineer can then tell you what your specific roof can carry.

Two more points from FEMA and WVU Extension:

• Design loads are for rare storms. FEMA says ground snow load maps show a load with a 2% chance of being equaled or exceeded in any year.
• They are not meant to last forever. WVU Extension says buildings are typically designed to hold the design load for only about a month.

How heavy is snow on a roof?

It depends on how wet and packed the snow is. A foot of fluffy snow weighs little. A foot of slush or ice weighs a lot.

WVU Extension gives another comparison: 2 feet of dry, powdery snow weighs just under 10 psf, while 2 feet of wet, dense snow weighs over 40 psf.

Maine’s figures turn the 20 psf rule of thumb into depths: about 4 feet of fresh snow, or more than 2 feet of old snow, may be too much for a typical roof. Two feet of old snow plus 2 feet of new snow could reach 60 psf.

How much does a foot of snow weigh on a whole roof? (our math)

Multiply the weight per square foot by the area of your roof. We use the roof’s footprint (the area it covers on the ground), since snow piles up on that area. Example: a 1,500 sq ft roof with 1 foot of snow.

Total weight = psf × roof area

The same foot of snow can weigh 4,500 pounds or more than 30,000 pounds. That is why the type of snow matters as much as the depth.

How to estimate the snow load on your roof

Method 1: Depth and type. Measure the depth near the edge with a yardstick from a safe spot, without climbing. Then use the table above. For example, using the middle of Maine’s range (about 5 psf per 4 inches of old, packed snow), 18 inches is about 18 ÷ 4 = 4.5 × 5 = 22.5 psf by our estimate.

Method 2: Water content. This is the method in University of Minnesota Extension’s 1983 report. Every inch of water weighs 5.2 psf. The National Weather Service says snow often averages close to 10 inches of snow per inch of water or less, though fluffy storms can run 15:1 or 20:1. So, by our math:

• 10 inches of average snow ≈ 1 inch of water ≈ 5.2 psf
• 30 inches of that snow ≈ 3 inches of water ≈ 15.6 psf

Wet, heavy snow has a lower ratio, so it weighs more per inch.

Ground snow is not roof snow. FEMA warns that 1 foot of snow on the ground does not always mean 1 foot on the roof. WVU Extension says wind often blows snow off, but drifts can pile up much more in some spots.

Where does snow pile up the most?

FEMA says drifts form when wind moves snow from one part of a roof to another. Watch these spots:

• Lower roofs next to a taller part of the house, such as a porch or garage below a second story. NDSU says multi-level roofs often collect deep drifts on the lower section.
• Next to walls, chimneys, rooftop equipment and other obstructions, which FEMA lists as common drift spots.

Steeper roofs shed snow more easily. UMN Extension says snow is unlikely to slide off roofs with a pitch of 3/12 or less, meaning 3 inches of rise per foot.

What are the signs of too much snow on a roof?

FEMA’s Snow Load Safety Guide lists these warning signs:

• Sagging ceilings, or ceiling boards falling out
• Popping, cracking and creaking sounds
• Sagging roof members or sheathing
• Bowed truss members
• Doors or windows that will no longer open or close
• Cracked or split wood
• Cracks in walls or masonry
• Severe roof leaks
• Water pooling on low-slope roofs

Maine adds doors that pop open, bowed pipes and bends or ripples in supports.

If you see these signs, get everyone out of the building. FEMA guidance says to contact a qualified design professional or your local building authority. UMN Extension says do not climb onto the roof or go back inside while the snow is still on it.

When should you remove snow from your roof?

Most of the time, you don’t need to. NDSU Extension says roof snow removal is “probably not necessary” for most homes. It also says the decision is largely an educated guess unless an engineer or building official advises you.

Consider removal when:

• There is more than a couple of feet of compacted snow (NDSU), or more than about 2 feet of old snow (Maine).
• Deep drifts build up on lower roofs or near walls.
• Ice has built up, which adds weight fast.
• You see any warning signs above.

UMN Extension says to clear the deepest snow first. FEMA says to start with drifts.

How to remove snow from a roof safely

• Stay off the roof. WVU Extension says do not climb onto your roof to shovel. Use a roof rake from the ground. FEMA guidance says working from the ground reduces the risk.
• Rake small amounts. Maine says to start at the edge, work up the roof and stand well back, since snow can slide onto you.
• Leave a layer. FEMA says to leave at least 2 inches. Maine says 2 or 3 inches. Scraping to the shingles can damage them.
• Go easy on shingles. NDSU says cold shingles are brittle and break easily. A rake with rollers keeps the blade just above them.
• No sharp tools. FEMA says not to use picks or metal shovels. UMN warns that chipping at ice can cause leaks.
• Look up for power lines. Maine warns that an aluminum rake conducts electricity, and WVU says a rake could conduct electricity.
• Protect yourself. Maine advises headgear and goggles. NDSU advises footwear with good grip.
• No heat tricks. Maine says not to use ladders, electric heaters or open flames to melt snow or ice.
• Hire a pro for the roof itself. FEMA says snow removal should be done by a licensed, insured professional roofing contractor, using fall arrest harnesses where applicable. WVU suggests lining one up in the fall, before you need it.

For clearing walks and driveways, see how to shovel snow safely. Raking the lower edge also helps with ice, covered in how to prevent ice dams.

How to get your roof ready before winter

• Clean gutters and downspouts so melting snow can drain (WVU, Maine). See how to clean gutters safely.
• Know your design load. FEMA suggests having a contractor or engineer inspect the building before the season if you don’t know what it was built for.
• Check your insurance. NDSU says some policies do not cover snow-related roof failure.
• Get the right tools early. A roof rake is easier to find before a storm. For driveways, see what size snow blower do you need.

For the rest of the house, use our winterize house checklist.