How and When to Remove Snow From Your Roof

a roof rake being used to remove snow from the roof of a house

How Snow Damages Your Roof

A heavy load of snow can cause damage to your roof and the interior of your home. Most roofing materials are designed to withstand a moderate to high amount of snow, but if the snow load exceeds the normal weight, it can cause damage.

Small holes and tears in the roof can form, creating interior damage from a leaking roof and poor heat retention in the attic. The most serious damage that can occur is a roof collapse due to too much snow accumulating on a weak or older roof.

This kind of damage does not always occur when there is snow on the roof, so it is a good idea to understand how to gauge the amount of snow on your roof and whether or not it is harmful to your home.

Benefits of Leaving Snow on Your Roof

In certain conditions, leaving snow on your roof may be a good idea. A light layer of snow provides insulation for your house as long as it is not heavy enough to cause damage. This can protect your roof from subzero temperatures. Thus, if you do need to remove snow from your roof, do not remove all of the snow; leave a thin layer to protect your roof from losing heat in the winter.

Things to Consider During Snow Removal

How Much Snow Your Roof Can Sustain. The amount of snow a roof can hold varies between roofing material manufacturers, but most residential roofs that are in good condition can sustain about 20 pounds per square foot of snow. Not all snow is created equal; snow weight depends on the age and temperature of the snow. The best way to estimate how much weight snow is adding to your roof is to calculate the Snow Load.

To understand the exact amount of snow that your roof can handle, contact the manufacturer or roofing company that installed the roof.

Roofing Materials. Metal roofs conduct heat better than asphalt roofs and allow for snow to fall off more easily. The exception to this is on a flat roof which doesn’t allow for snow to shed and has a higher chance of ice dams forming.

Temperature Fluctuations. Thawing and freezing can cause snow to become heavier as it gathers ice. When temperatures drop and rain falls on top of the snow, the load becomes heavier from the added ice. Freshly fallen dry snow will weigh less than old, wet snow, so it’s important to keep an eye on when snow is collecting on your roof.

The Age of Your House. Roofing requirements change over time. Along with the deterioration of an older roof, the weight of snow that can be sustained will decrease. If you have an older roof but aren’t ready to replace it, be sure to pay attention to the condition and keep up with repairs in the warmer months.

How to Calculate Snow Load

Figuring out how much weight snow is adding to your roof may seem tricky, but there is a calculation that allows you to accurately estimate snow load:

(S x 1.25lbs)+(I x 5.2lbs) = P

In this equation:

S = inches of snow on the roof (depth)

I = inches of ice buildup on the roof (depth)

P = pounds per square foot (lbs/sq ft)

The approximate weight of snow for each 1 inch of depth per square foot is 1.25lbs and the approximate weight of ice for each 1 inch of depth per square foot is 5.2lbs. 

Measure the depth of snow and ice on your roof to find the pounds per square foot of weight on your roof. If it exceeds the amount of snow your roof can sustain, you should think about clearing snow from your roof.

You can find a more detailed Snow Load calculator on the PolarMade site.

Signs There’s Too Much Snow on the Roof

Interior Damage. A large snow load can cause roof damage that, in turn, causes damage inside the house. As the snow melts on the roof, it can trickle through cracks and cause water damage on ceilings and walls. Water damage can also cause infrastructure issues as it warps wood studs. If there are brown stains forming inside your house during colder months, it’s a good idea to clear the roof of snow.

Ice Dams and Icicles. Poorly insulated roofs cause snow to melt and form ice dams. As the snow refreezes and melts over and over, gutters and the space beneath shingles expand and contract to cause ice dams and icicles. Ice weighs five times as much as snow and can cause major damage to your roof. Though they might look pretty, icicles are a sign that your roof needs to be cleared.

Doors Not Closing Inside the House. A less obvious sign that the snow on your roof is too heavy is that doors are difficult to close, specifically in the middle of your house. As snow pushes down on the roof, it puts pressure on door frames and causes doors to get stuck. The effect on the doorframe is likely not visible to the naked eye, but any pressure that causes this change can be dangerous to your home.

Removing Snow

If you have decided to remove snow from your roof, there are several things to keep in mind. The number one rule is to practice safety measures and hire a professional if there is any danger in removing snow from your roof.

Prepare the area. First, clear the perimeter of your house to avoid trudging through more snow while trying to clear your roof. Stay on the ground while removing snow from the roof and make sure there aren’t any tables, ladders, or other obstacles that will interfere with the process.

Be Aware of Conditions. Before starting, check to make sure there isn’t a storm coming or other weather conditions that will make it harder to work. Take note of hazards like icy ground cover or power lines that present extraneous dangers.

Use the Right Tools. When clearing snow, use a long-handled tool like a roof rake or throw the midsection of rope onto the roof and pull the snow down. A shovel is the riskiest tool to use because it can cause damage to shingles when pulling the snow down. If you need to use a shovel, be extremely careful and do not use a metal shovel, which can cause more damage.

Avoid Getting Buried. While pulling snow from the roof, use lateral movements to avoid getting covered in snow. Take a step back after clearing and allow the snow to fall in front of you and, if necessary, clear the ground around you every once in a while to create more room to move.

Be Safe! DO NOT CLIMB ON YOUR ROOF. There are many scenarios that present danger when clearing snow from your roof. Falling from a slippery roof is a serious accident that can result in injury or death. If you have back issues, a heart condition, or other health problems that may interfere with your ability to clear snow, do not attempt to remove snow yourself.

When to Hire a Professional

Because of the risks involved in clearing your roof, call a professional at the first sign of doubt that you can safely remove snow from your roof. These reasons may go beyond personal ability, including a particularly snowy or icy roof, a high roof that cannot be reached, or other environmental hazards. Professionals have the experience and equipment to carry out dangerous tasks safely. No household maintenance is worth risking your life!