The average annual snowfall can vary quite a bit in Virginia, ranging from 10 inches in Richmond to 52 inches in Wise. Maryland shovels 20 inches in Baltimore and more than 100 inches in Oakland.
While snow may look beautiful as it drifts down and coats everything in pristine white, it also brings substantial amounts of water. The general rule is that 13 inches of snow equals one inch of rain. Collected on a 2,800-square-foot roof, it adds up to 1,743 gallons of water.
That’s what happens with average snow. Powdery, fluffy snow is more in the range of 1,000 gallons. Heavy, wet snow could bring more than 5,000 gallons.
Snow, Ice, and Water
It can be a significant amount of water that collects in the form of snow on your roof. That same amount of snow is also covering your lawn, shrubs, and trees. As it melts during the day, the resulting water saturates the soil and can build up an underground water flow toward your home’s foundation.
This happens as a result of the clay bowl effect. When the soil is excavated during construction and then backfilled around the foundation, that soil has a different drainage factor than the undisturbed soil surrounding your home. This means water can easily flow toward your basement or crawl space, building up hydrostatic pressure that can cause cracking and flooding.
A further factor is snow stacking up around your home. That could be from blowing and drifting snow as well as snow removal from sidewalks and driveways. When it melts, either quickly or over time, the water flows directly to the already oversaturated soil.
Then there’s the snow on your roof. Melting during the day due to sunlight and warmer temperatures is followed by freezing at night, forming ice. That can lead to freezing gutters and downspouts. It can also lead to a buildup of ice along the edge of the roof, forming ice dams. All that traps the water on the roof, forming still more ice.
Another reason behind melting snow on the roof and around the foundation is heat escaping due to insufficient insulation in the attic and the foundation walls. The subsequent melting once again leads to the soil around the foundation.
Snowmelt Water Flow
Gutters, downspouts, downspout extensions, and landscape grading are all designed to move water away from the foundation. When gutters and downspouts freeze up, the snowmelt runs off the roof and drops directly onto the soil around the foundation.
If the soil is frozen, the water pools up and freezes, just waiting for the next thaw to find its way into your basement or crawl space. More likely the soil will already be saturated with melting snow and the flow from the roof will compound the hydrostatic pressure building up, seeking or creating openings in the foundation walls.
Snowmelt Mitigation
The key to protecting your home from snowmelt and from excess snow and ice is prevention. Here are our recommendations:
- Clear Rooftop Snow. Use a roof rake to pull excess snow off the roof. This prevents ice formation and excess snowmelt.
- Remove Snow Around the Foundation. After you’ve raked the roof, shovel the snow around your foundation, clearing a space of at least four to six feet. This helps get excess water away from the foundation.
- Downspouts and Gutters. Make sure they are clear and sufficiently sized to handle the expected flow of water. The downspout extensions and landscape grading need to move snowmelt away from your foundation.
- Insulate Your Attic and Foundation. Heat rising through the roof or around the foundation causes snowmelt and water to flow toward your foundation. Adding insulation can help prevent this and save on energy costs.
- Basement or Crawl Space Waterproofing. Fix any cracks, which can become bigger when water enters and freezes. Install an interior drainage system and sump pump that will remove any water before any resulting damage.
- Sump Pump Maintenance. Make sure the drain lines are working, as well as the backup battery. Freezing drain lines can burn out the sump pump and allow water accumulation.
For professional advice on protecting your home from winter weather and spring snowmelt, schedule a free inspection and repair estimate from the basement waterproofing and foundation repair experts at JES Foundation Repair.
