By far, the most common cause of a leaky basement is heavy rain; did you know that melting snow has pretty much the same effect as heavy rains as a cause of leaking basements? In this post we discuss how melting snow is equivalent to heavy rain, how melting snow causes basement leaks and the prevention and repair of basement leaks attributable to snow melts.
Melting snow is equivalent to heavy rain
Just like rain, melting snow is precipitation.
To convert the amount of snowfall to precipitation there is a rule of thumb that 10 inches of snow, if melted, would produce one inch of water. To put this into perspective, an inch of snow produces about 2700 gallons of water per acre; that’s alot of water (The 10:1 ratio also assumes a ‘perfect’ snowmelt where there is no water lost to evaporation or other losses)! Naturally, the actual amount of water produced by melting snow varies considerably depending on whether the snow is wet and heavy, or fluffy and relatively dry.
Heavy, wet snow has a very high water content such that 4 – 5 inches of heavy wet snow is equivalent to about one inch of water. On the other hand, you could require 20 inches of dry powdery snow to produce the equivalent of one inch of water.
How melting snow causes basement leaks
If an inch of melting snow produces 2700 gallons of water per acre, even a minor snow melt can deposit thousands of gallons of water around your foundation. If you combine melting snow and a springtime rainfall, the amount of water in the soil will be even greater and result in a significant rise in the height of the water table as well as a dramatic increase in the amount of hydrostatic pressure (water pressure) against a foundation.
These environmental conditions represent a “stress test” on your foundation; if your foundation is vulnerable to penetration by ground water, you will end up having water in your basement.
When the outside air temperature is warm, rain water is absorbed by the soil which will exert hydrostatic pressure against your foundation walls. During the winter, the ground is frozen so surface water absorption from the soil is virtually nil; as a result, the water produced by a snow melt pools on the surface until it finds a place to drain away. Your warm foundation thaws the soil next to your home, thus facilitating the flow of water into the soil around your foundation. Inevitably, some of that water is going to find its way down your foundation walls and end up in your basement.
Check out our page on the typical sources of basement leaks.
Can basements be waterproofed in winter or when snow is melting?
If it weren’t possible to waterproof a basement, or at least stop a foundation leak during a time when the snow is melting, it would be a catastrophic situation. This doesn’t mean that the weather and time of year doesn’t matter; actually, it matters very much.
When the snow is melting the methods used to waterproof a foundation or fix a basement leak need to take into account the environmental conditions. There are three challenges when waterproofing a foundation in the winter / spring: the outside air temperature, the condition of the soil and the condition of the foundation.
Challenges to waterproofing basement walls during cold / wet weather
During the winter and much of the spring, the outside air temperature is low enough to freeze water. Temperature is a very big deal when you excavate the exterior of a wall to waterproof it. Foundation waterproofing coatings must be solvent based to withstand freezing temperatures; this is a problem because the cure time is several days and the odour of the solvent gets into the home for at least a week.
Wet exterior foundation walls are also a problem because the coatings used in basement waterproofing do not adhere properly to the foundation. The wall must be dry if the coating is to withstand the test of time.
Finally, it is unsafe to excavate mud, and the freezing and thawing cycles do increase the likelihood that the soil will cave in to the excavated area while the foundation coating is curing on the walls.
As a result, exterior excavation of foundation walls during the winter is a bad idea.
Waterproofing methods suited to cold weather snow melts
If your home was built after the late 1970’s, chances are you have a poured concrete foundation. This type of foundation typically leaks through concrete cracks or tie-rod holes.
Fixing foundation cracks and tie-rod hole leaks during the spring is not a problem when done by polyurethane injection. This basement leak repair method involves injecting, under pressure, resin into the leaking cavity (crack or tie-rod) in the foundation. Polyurethane resin expands and fills the cavities into which it is injected and is not adversely affected if the basement wall is leaking. A polyurethane injection repair of a basement leak is as low cost as it gets. See this article on the cost of injection.
While polyurethane injection is not a viable foundation wall leak repair method for concrete block and cinder block foundations, a block foundation can be waterproofed when actively leaking and when it is cold outside. A concrete block foundation can be very effectively waterproofed using an interior perimeter drain system which is a way to waterproof block foundation walls by draining the blocks and transporting the water to a sump pump for evacuation.
Click on this link for an exhaustive listing of available basement waterproofing methods.
How to prevent a basement from leaking when the snow melts
When it comes to leaks that happen when the snow melts, many homeowners will acknowledge that they have had problems in years past. If the wet basement problem still hasn’t been addressed it is usually because of fear concerning the cost of waterproofing the basement. Nothwithstanding, the best way to prevent and avoid a wet basement due to melting snow is to have the basement leak repaired before the annual spring thaw. Remember the old adage, “an ounce of prevention is better than a pound of cure.”
Read our article on wateproofing cost
If you’re stuck with an active leak you can temporarily stop cracks from leaking using hydraulic cement available at every hardware store. You might also have success stopping other basement leaks using this method but it will depend on the hydrostatic conditions around your foundation. However, this quick fix is temporary and traps ground water in your foundation walls, which causes deterioration of your foundation. Using hydraulic cement to stop a basement leak is, at best, only a short-term band-aid solution.