Water is the most destructive force acting on your home — and most of the damage it does begins outside, long before it ever reaches your basement. Poor drainage around your foundation is the root cause of wet basements, foundation cracks, landscape erosion, and structural damage in Ontario homes. The good news: most drainage problems have affordable solutions if you catch them early enough.
Signs of Poor Drainage Around Your Home
Many homeowners don't recognize drainage problems until they show up as a wet basement or visible foundation damage — by which point significant harm may already be done. Learning to identify early warning signs dramatically reduces the cost and complexity of the solution.
External warning signs:
- Water pooling against or within 10 feet of the foundation wall after rain
- Erosion channels in lawn or garden beds near the house — rills carved by concentrated water flow
- Soil that stays wet for days after rain while the rest of the yard drains normally
- Efflorescence on exposed foundation concrete — white salt deposits left behind by evaporating water
- Algae or mold growth on foundation walls or lower siding courses, indicating persistent moisture
- Downspouts that terminate at the foundation wall or in adjacent garden beds
- Grade that slopes toward the house rather than away
Internal warning signs (in the basement):
- Damp or wet basement walls, especially after rain events
- Musty odor that worsens in spring and fall
- Water staining at the base of foundation walls
- Condensation on walls that is connected to exterior rain events
- White mineral deposits (efflorescence) on interior concrete or block walls
If you're seeing multiple internal signs, drainage improvement alone may not be sufficient — interior waterproofing may also be needed. Start with external drainage improvements first, as they address the source of the problem rather than just managing its consequences.
Pro Tip: Do your drainage assessment during or immediately after a heavy rain event — not on a dry day. Wet conditions reveal exactly where water flows and where it collects. Take photos or videos of problem areas during rain; contractors can use these to understand the problem before visiting your property.
Grading: The First and Most Impactful Fix
In the majority of Ontario homes with drainage problems, the root cause is inadequate or reversed grading. Grading refers to the slope of the ground around your home's foundation. Building codes and sound construction practice require the ground to slope away from the foundation at a minimum rate of 6 inches over the first 10 feet — that's a 5% slope.
Over time, this slope disappears. Soil settles. Garden beds are filled in without maintaining proper grade. New landscaping is added without attention to drainage. Tree roots alter soil levels. And slowly, the ground that used to direct water away from your house begins directing it toward it.
How to assess and correct grading:
- Walk the perimeter of your home with a long level or use a line level and string to measure the slope of the ground from the foundation outward over 10 feet.
- Identify all locations where the grade is flat or running toward the house.
- For minor re-grading, add a layer of clean fill soil (not topsoil — fill has less organic material and compacts better) and slope it appropriately away from the foundation.
- Compact the fill and add a shallow layer of topsoil and sod or landscaping on top.
- Keep added soil at least 6 inches below the siding bottom edge to prevent moisture contact with wood or vulnerable materials.
Cost for DIY re-grading: $100-400 for materials depending on the scope. Professional re-grading for a typical property runs $500-1,500. This is one of the highest ROI investments you can make in foundation protection.
Downspout Extensions: The Lowest-Cost, Highest-Impact Fix
After grading, downspout extensions are the most impactful drainage improvement you can make for the least money. A downspout that terminates at the foundation wall is actively directing every litre of roof runoff at the most critical point of your home's structure. Adding an extension that carries that water 4-6 feet away changes that dynamic completely.
Roof surfaces are large. A typical 1,500 square foot bungalow in KW receives several thousand litres of runoff in a single heavy rain event. That water concentrates into your gutters and exits through 4-8 downspouts. If even one of those downspouts terminates against your foundation, the impact over a full Ontario rain season is enormous.
Downspout extension options:
- Rigid aluminum or vinyl extensions: The simplest solution — attach a pre-formed extension to the downspout elbow to direct water away. Cost: $10-25 per downspout. Limitation: can be a trip hazard and may be displaced by mowing or snow clearing.
- Flexible accordion extensions: Slightly more expensive, can be folded over the driveway when not needed and extended back over the lawn. Cost: $15-30 each.
- Underground drain pipes: The most elegant solution — a buried perforated or solid pipe carries water from the downspout to a pop-up emitter in the lawn or to a street drain. Cost: $200-600 per downspout installed professionally, but invisible and permanent.
- Rain barrels: Capture roof runoff for garden use, reducing the volume of water reaching the foundation. Not a complete solution for high-volume rain events, but reduces everyday impact.
Don't underestimate proper downspout function as a whole system. Even well-extended downspouts are useless if the gutters are clogged and water is overflowing at the fascia instead of reaching the downspouts at all. Regular gutter cleaning is prerequisite to any downspout improvement making sense.
French Drains: When Surface Solutions Aren't Enough
For persistent drainage problems that can't be resolved by grading and downspout extensions — typically cases where the natural topography channels water toward the house, or where clay soil prevents adequate drainage — a French drain may be the solution.
A French drain is a subsurface drainage system that intercepts groundwater before it reaches the foundation. It consists of a perforated pipe surrounded by gravel, wrapped in filter fabric, buried at an appropriate depth to intercept and redirect groundwater flow.
There are two common configurations for residential use in Ontario:
- Perimeter French drain (curtain drain): Installed along the uphill side of the house to intercept surface and subsurface water flowing toward the foundation from higher ground. This is effective for homes on slopes where water runs downhill toward the house.
- Foundation French drain: Installed at the base of the foundation wall to collect water that reaches the foundation and redirect it to a sump pump or daylight outlet. This is more invasive (requiring excavation to foundation depth) but is the standard solution for serious foundation water problems.
French drain installation costs in Ontario typically range from $1,000-5,000 for surface curtain drains, and $5,000-15,000+ for full foundation perimeter systems that require significant excavation. These are professional projects — they require proper design, appropriate pipe depth and slope, filter fabric installation to prevent soil infiltration, and an adequate discharge point.
Permits may be required for significant drainage alteration work in Ontario, particularly if water is being redirected to storm sewers, ditches, or neighbouring properties. Check with your municipality before beginning any major drainage project.
Window Wells: A Common and Overlooked Drainage Failure
Basement egress windows and utility windows that are below grade need window wells — the semicircular barriers that hold soil back from the window opening. These wells can be a significant source of water infiltration if not properly maintained and drained.
Every window well should have a layer of drainage gravel at the bottom (typically 12-18 inches deep) and either an underground drain pipe or sufficient depth to hold rainfall without reaching the window. In many Ontario homes, particularly in older subdivisions, window well drains are absent, undersized, or clogged with years of accumulated debris.
Annual window well maintenance includes:
- Removing accumulated leaves, dirt, and organic debris from the well each fall
- Checking that the gravel layer is still present and at adequate depth (add gravel if the gravel has compressed or settled below the drainage level)
- Testing the drain (if present) by filling the well with a hose and observing how quickly it drains
- Installing a window well cover — a clear polycarbonate dome that keeps debris and the majority of rain out while still admitting light
Window well covers are an inexpensive and highly effective way to prevent window well flooding. They attach to the window well frame and shed rain away from the well opening. Cost: $40-100 per window well. The reduction in basement water infiltration risk from this simple addition can be dramatic.
Swales and Berms: Reshaping the Land
For properties where water flows across a large area toward the house, swales and berms can redirect surface water around rather than toward the foundation. These are landscaping solutions that work with the natural movement of surface water.
A swale is a shallow, gently sloped channel designed to collect and redirect surface water. Unlike a drainage ditch (which is purely functional), a well-designed swale can be vegetated with grass or native plantings and become a landscape feature. Swales should be designed to carry water to an appropriate outlet — a storm drain, a municipal ditch, or a low point at the back of the property where natural infiltration occurs.
A berm is a raised ridge of compacted soil that acts as a barrier to redirect water flow. Berms are typically constructed on the uphill side of a problem area, redirecting surface runoff around the sides of the house rather than through the foundation zone. Like swales, berms can be attractively landscaped and become part of the property design rather than looking like emergency earthworks.
Both swales and berms require careful design to ensure they don't simply redirect water onto a neighbour's property. In Ontario, you are legally responsible for ensuring that drainage improvements don't adversely affect neighbouring properties. A professional landscape contractor familiar with Ontario drainage standards can design solutions that comply with local requirements.
When to Call a Professional
Most homeowners can handle simple drainage improvements — downspout extensions, minor re-grading, and window well maintenance are all reasonable DIY projects with minimal investment and risk. But some drainage situations require professional assessment and intervention.
Call a professional when:
- You're seeing water entry through the foundation wall or floor — not just dampness, but actual water infiltration
- Foundation cracks are present, particularly horizontal cracks in poured concrete or step cracks in block walls
- The drainage problem has not improved despite basic measures (re-grading, downspout extensions)
- Your home sits at the bottom of a slope and receives surface runoff from neighbouring properties
- You're in a municipality that requires permits for drainage work
- The problem area is near your property line (potential impact on neighbours)
| Solution | DIY Possible? | Estimated Cost | Best For |
|---|---|---|---|
| Downspout extensions | Yes | $10–30 each | All homes with inadequate discharge |
| Surface re-grading | Yes (minor) | $100–1,500 | Flat or reversed grade near foundation |
| Window well covers | Yes | $40–100 each | Below-grade windows flooding |
| Underground downspout drains | Possible (with planning) | $200–600/downspout | Aesthetic solution; eliminates surface hazard |
| Curtain/French drain | No — pro required | $1,000–5,000 | Water flowing toward house from uphill |
| Swale installation | Minor DIY possible | $500–3,000 | Large surface water redirection |
| Foundation perimeter drain | No — pro required | $5,000–15,000+ | Serious foundation water infiltration |
Home Drainage — Key Takeaways
- ✓ Check grade first: The ground should slope 6 inches away over the first 10 feet from the foundation — this is the most impactful and affordable fix.
- ✓ Every downspout needs a proper extension: 4-6 feet minimum discharge from the foundation; underground pipes are the best long-term solution.
- ✓ Window wells need annual maintenance: Clear debris each fall and verify drain function before winter.
- ✓ Document problems during rain: Photos and video of water pooling during a storm are invaluable for diagnosing the problem and communicating it to contractors.
- ✓ Start simple, escalate if needed: Grading and downspout extensions solve the majority of drainage problems at minimal cost — French drains and waterproofing are for problems that persist after the basics are done.
