The soil your home is built on holds hundreds of gallons of water in every 1000 sq ft of soil for every inch of rain that falls. That’s around 20,000 lbs. or about 10 tons of water. And it’s sitting right next to your basement walls.
How water actually destroys foundations
Water isn’t the main problem when it comes to your foundation – it’s water in the soil surrounding your foundation. When soil gets wet, it doesn’t just get softer. It exerts hydrostatic pressure, a horizontal force, against concrete walls. This force can be extremely strong. Saturated soil can exert several hundred pounds of pressure per square foot against concrete. Concrete is actually very porous and will crack with enough force. Once they begin forming, cracks will widen with each rain and freeze/thaw cycle since trapped moisture causes water to expand when it freezes and contract when it thaws. The most common early warning sign that water is getting into your foundation, not just surrounding it, is efflorescence, the white, chalky substance that forms on basement walls or on brick at the base of your home. This is the salt left behind when water infiltrates the concrete and later evaporates.
The grading rule most homeowners get wrong
Landscape grading away from the foundation is the cheapest foundation defense there is, and most houses either weren’t graded properly to begin with or have settled over the years.
The rule is simple: the ground immediately surrounding your home should fall at least 6 inches in the first 10 feet away from the foundation wall. That slope keeps surface water flowing away from the building instead of collecting against it. Settled mulch beds, settled garden borders, and decades of minor erosion can wear that slope away and in some cases even invert it so the ground actually tips back toward the house.
After a heavy rain, walk your property’s perimeter. If you see standing water within 10 feet of your foundation, or if you see water running toward the house, the grade needs correcting. Most homeowners can add soil and regrade over a weekend, though this really is a case where close enough isn’t good enough.
Gutters move the problem; downspout extensions solve it
Typical gutters collect roof water but move it to the corners of your house through downspouts, often just a few inches from the foundation. That’s not draining; that’s moving.
Downspout extensions should direct water at least 5 to 10 feet away from the foundation. Corrugated extensions can work, but buried rigid piping that discharges well away from the property is a more permanent and reliable solution.
If gutters are pulling away from the fascia, backing up, or overflowing, they may be directing roof water straight down beside the foundation. Keeping gutters and downspouts clear and properly positioned helps prevent this.
Clean the gutters twice a year. Check the spouts with a hose to make sure they are draining and the water exits completely clear of the house.
Regional soil types raise the stakes considerably
Every house isn’t equally vulnerable, and soil composition is the variable that poses the greatest risk. Expansive clay-like soils (the kind you find in semi-arid and transitional climate zones) essentially act as a slow-moving hydraulic lift against the walls of your foundation. When wet, they can swell by over 10% of their size. When dry, they shrink and create gaps between the foundation and the soil. This swelling and contracting cycle exerts an incredible amount of pressure against concrete… and the cracking that results is cumulative.
The ASCE estimates that 1 in 4 homes in the United States suffers some structural damage due to expansive soils – to the tune of billions of dollars in repairs each year.
When late-season snowmelt combines with frozen ground from the dry winter, it exacerbates the issue further because there’s nowhere for the water to go. It can’t be absorbed into the ground, so it flows directly into your foundation. This is when people who’ve never previously had a problem can suddenly be wading in a few inches of water. This is also when Water damage restoration Denver, CO companies are called in as a flood of water seeps into the basement, submerges the sump pump, and starts to damage drywall and studs.
Subsurface solutions for when grading isn’t enough
Some properties are located where the water table is naturally high, or soil drainage is poor no matter the slope. In those cases, water drains onto the foundation naturally over and through the soil no matter the grading, and often through non-draining window wells.
A French drain – a perforated pipe in a gravel-filled trench – intercepts this insinuating groundwater and carries it to daylight or a sump pit. With geotextile fabric and 4 to 6 inches of gravel surrounding the drain, it acts as a water filter, keeping soil fines from entering the drain and restricting flow.
Interior sump pumps work alongside sub-surface drainage systems, collecting water that enters below-grade areas and removing it automatically before it becomes visible.
A sump pump without a drainage system is little more than a hole in the floor, so both are essential. If your basement has experienced repeated damp seasons, consider adding a battery backup in case of power cuts or pump failure, particularly during heavy storms when pumps are working hardest.
Brick veneer walls use a similar principle through weep holes. These small openings at the base of the wall allow water trapped behind the brickwork to escape rather than reaching the interior drywall. They can easily become blocked or covered during painting and landscaping work.
Protecting a foundation requires more than one solution. Proper grading, gutters, sub-surface drainage, and interior water removal all need to work together. The best time to check these systems is before the ground becomes saturated and water enters the basement.
