Check Exterior Drainage System
The first line of defense against basement moisture is keeping water away from your foundation. Proper exterior drainage prevents the majority of basement water problems.
Why Exterior Drainage Matters
Most basement water problems start outside, not inside. When gutters overflow or your yard slopes toward the house, thousands of gallons of water pour directly against your foundation during every rainstorm. Even the best interior waterproofing can't handle that volume. Fixing exterior drainage is cheaper and more effective than any interior solution. A $200 investment in downspout extensions can eliminate problems that would cost $10,000+ to fix with interior waterproofing.
Tools & Materials You'll Need
Step-by-Step Guide
Inspect and Clean Gutters
Walk around your entire house and check every gutter section:
- •Remove all leaves, debris, and dirt from gutters using a scoop
- •Check that gutters slope toward downspouts (1/4 inch per 10 feet)
- •Look for sagging sections that need re-hanging
- •Repair or seal any leaking seams or holes
- •Flush gutters with garden hose to verify proper flow
Quick Test: Pour water from a bucket into each gutter section. Water should flow smoothly to downspouts without pooling. Pooling indicates improper slope.
Check Downspout Placement
Downspouts are only useful if water discharges far from your foundation:
- •Measure distance from downspout end to foundation - should be 6-10 feet minimum
- •Verify downspouts are securely fastened to house with brackets every 10 feet
- •Check that elbows and joints are sealed and don't leak
- •Ensure water doesn't discharge onto driveways or walkways that slope back toward house
Common Mistake: Downspouts that empty 2-3 feet from the foundation create more problems than they solve. Water flows right back to your basement.
Add Downspout Extensions
The single most cost-effective drainage improvement you can make:
Option 1: Flexible Extensions
Attach 6-10 foot flexible corrugated extensions to each downspout. Cost: $10-15 each. Quick to install but less attractive and can be trip hazards.
Option 2: Rigid Extensions
Use matching rigid downspout material extended 6-10 feet. Cost: $20-30 each. More attractive and durable but requires cutting and fitting.
Option 3: Underground Drainage
Bury 4-inch perforated PVC pipe from downspout to discharge point 10-20 feet away. Cost: $50-150 per downspout. Most effective and best looking but requires digging.
Assess Foundation Grading
The ground around your foundation should slope away to carry water away from the house:
How to Check Grading:
- Place a 10-foot board or level extending from foundation outward
- Measure height difference from foundation to 10-foot mark
- Should drop at least 6 inches over 10 feet (5% slope)
- Walk around entire house checking all sides
- Mark problem areas where ground is flat or slopes toward house
Improve Problem Grading
Fix areas where water pools or flows toward your foundation:
For Minor Issues:
Add topsoil or clay soil to create proper slope. Pack firmly and seed or sod. Cost: $50-200 per problem area. This is a DIY-friendly fix that solves most issues.
For Persistent Water Pooling:
Install a swale (shallow drainage ditch) to redirect water around problem areas. Line with river rock for erosion control. Cost: $100-300 for DIY installation.
For Severe Problems:
Consider a French drain system - perforated pipe buried in gravel that intercepts water before it reaches foundation. Professional installation: $2,000-6,000.
Pro Tips
- ✓Test your drainage during the next rainstorm - walk around and watch where water flows
- ✓Consider gutter guards to reduce cleaning frequency ($5-10 per linear foot installed)
- ✓Use splash blocks at extension ends to prevent erosion and direct water flow
- ✓Don't discharge onto neighbor's property - it's illegal in most areas
- ✓Mark problem areas with stakes during dry weather so you remember where to fix
Frequently Asked Questions
How far should downspouts extend from the foundation?▼
Downspouts should discharge water at least 6-10 feet away from your foundation. Closer than 6 feet, and water will flow back toward the basement. Use rigid or flexible extensions, or install underground drainage pipes to carry water further away.
What slope should my yard have away from the house?▼
Your yard should slope away from the foundation at a minimum of 6 inches drop over 10 feet of distance. This 5% grade should extend at least 10 feet from the house. Steeper is better, but this minimum ensures water flows away instead of pooling against the foundation.
How often should I clean my gutters?▼
Clean gutters at least twice per year - in late spring after tree pollination and in late fall after leaves drop. If you have many trees near your home, clean them quarterly. Clogged gutters overflow and dump water right against your foundation, causing basement moisture problems.
Can I fix drainage problems myself or do I need a professional?▼
DIY fixes include cleaning gutters, adding downspout extensions, installing splash blocks, and adding topsoil to improve grading. Hire a professional for major grading work, French drain installation, underground drainage systems, or if you have persistent water problems despite basic fixes.