An average year in Minneapolis sees 54 inches of snowfall spread over 37 days. In Duluth, expect 86 inches. In Fargo, ND, plan on 50 inches, and in Bismarck, 51 inches. That’s coupled with winter temperatures that seldom get above freezing.
With that in mind, snowmelt can appear to be an upcoming blessing as warmer temperatures return. Unfortunately, there’s also a great deal of downside including damage to your home’s foundation and even basement or crawl space flooding.
Rooftop Snow Accumulation
A gentle snowfall can cover everything with a pristine blanket of white. Then the next round of snow arrives, adding more to the blanket. But, of course, it doesn’t stop there. It keeps building up, compressing, and adding serious weight to your home’s roof.
Most roofs are built to hold 20 pounds of snow per square foot. Roofs with lower slopes can be expected to hold onto that snow while steeper roofs may shed some of the weight through melting and even blowing off with high winds.
Lawn Snow Buildup
It doesn’t stop at your roof. Snow covers everything in your yard, concentrating, for some reason, on your driveway where you have to clear it, often every day.
Then there are the snowdrifts that can blow up against your home, building up snow directly on the foundation. Clearing that snow from your driveway and sidewalks leads to still further buildup of snow, ice, and the water they contain.
Snow’s Water Content
It’s not the snow or even the ice that causes flooding, but the water from the melt. The general rule is that 13 inches of snow equals one inch of rain. On a 2,800-square-foot roof that adds up to just over 1,700 gallons of water. Wet, heavy snow could come in at more than 5,000 gallons.
Snowmelt’s March to the Basement or Crawl Space
All that water has to go somewhere as the temperatures rise. Not only that, but slight warming during the day, along with any heat escaping through the attic, can cause early water flow under the snow covering. This water moves into the gutters and downspouts forming ice overnight that stops the flow of any further melting.
That, in turn, forms an ice dam that blocks the water, which freezes at night. All this adds weight to your roof while storing up water for the springtime thaw to come.
This slight melting also happens on your lawn and particularly under the snowdrifts or stacked-up snow. That melt saturates the soil, forms pools of water, and causes underground water flow.
That underground water flow moves toward the foundation due to the clay bowl effect. This is due to the excavation when building the basement or crawl space followed by backfilling around the foundation with that same soil. That backfill soil is loose and not as dense as the surrounding undisturbed soil. This helps the water flow directly around the foundation.
There is also a resultant gap between the foundation walls and the surrounding soil. Water builds up in that gap as well as from the underground flow from the surrounding soil causing hydrostatic pressure. That pressure can cause cracks that bring leaks and even flooding to the basement or crawl space.
In the middle of winter, it can be very challenging to effectively address the coming thaw and snowmelt. Prevention is the best policy. Here are our tips to help you handle snowmelt.
- Remove Rooftop Snow. As noted above, rooftop snow accumulation not only adds weight but essentially stores water in the form of snow and ice. It’s best to do what you can to remove some of that snow using a roof rake.
- Clear Foundation Snow. Snow can build up in drifts around the foundation. It can also stack up from scooping snow off sidewalks and driveways. It’s best to clear the snow to a distance of four to six feet all the way around your home.
- Install and Maintain Gutters, Downspouts, and Extensions. Snowmelt from the roof moves through the gutters into the downspouts and ideally through the extensions onto your lawn that has been properly graded to facilitate flow away from the foundation. Make sure the gutters and downspouts are clear, free of leaves and obstructions. Consider placing extension lines in the ground to direct the water well away from the foundation.
- Cover Basement Window Wells. Snow can accumulate in basement window wells. Provide watertight covers and drainage to prevent water from entering through the window.
- Install Proper Waterproofing and Drainage. Fix any cracks and install an interior drainage system, including a sump pump to clear any leaking water. Make sure any existing drainage systems are clear and protected from freezing.
- Add Insulation to Attic and Foundation Walls. Heat can escape from the attic or foundation walls to cause melting and ice formation. To prevent this, add sufficient insulation, which can also save on heating costs.
To schedule a free foundation inspection and repair estimate as well as identify ways to improve your home’s insulation, drainage, and waterproofing, contact your local foundation repair experts at Innovative Basement Authority.