Grading and drainage conditions are the first line of defense against water intrusion—the leading cause of foundation damage, basement flooding, and structural deterioration. With foundation repair costs averaging $4,500 to $15,000 and water damage remediation running thousands more, thorough drainage inspection protects buyers from costly surprises. This comprehensive grading and drainage inspection checklist covers slope assessment, drainage paths, erosion signs, gutters, downspouts, and water management systems—ensuring you identify risks before they become expensive problems.

Compliance Note: This checklist follows ASHI and InterNACHI Standards of Practice for site and drainage inspections. Inspectors evaluate visible grading and drainage components accessible from ground level. Buried drainage systems cannot be fully evaluated without specialized equipment. Document limitations and recommend further evaluation when drainage problems are suspected.

Why Grading and Drainage Inspection Matters

Drainage defects are found in approximately 35% of home inspections—making them among the most common issues identified. Improper grading directs water toward foundations, causing basement leaks, crawlspace moisture, foundation settlement, and structural damage over time.

35%Inspections find drainage issues
6"Minimum slope per 10 feet
$4,500+Average foundation repair
90%Wet basements from poor drainage

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Before You Begin: Assessment Approach

Effective drainage inspection requires systematic evaluation of the entire property. Follow these assessment protocols:

Walk the Perimeter

Circle the entire foundation examining grade, soil conditions, and water flow patterns. Note low spots where water could pool against foundation.

Check After Rain

Recent rainfall reveals drainage problems. Look for standing water, saturated soil, erosion channels, and water staining on foundation walls.

Follow the Water

Trace water flow from roof to property edge. Identify where downspouts discharge and whether water is directed away from foundation.

Document Everything

Photograph grading issues, erosion, standing water, and drainage components. Include measurements where slope deficiencies exist.

Complete Grading and Drainage Inspection Checklist

1

Site Overview & Topography

5-10 min

Begin with overall site assessment to understand natural drainage patterns and identify areas requiring detailed inspection.

General Site Conditions

Pro Tip: Walk the property after rainfall when possible. Standing water, saturated soil, and erosion patterns are much easier to identify when drainage problems are actively visible.
2

Foundation Perimeter Grading

15-20 min

Proper grading away from the foundation is critical. The ground should slope away at minimum 6 inches over the first 10 feet to direct water away from foundation walls.

Grade Assessment - All Sides

Soil & Ground Cover

Foundation Clearance

Common Grading Defects
  • Negative grade: Ground slopes toward foundation—water directed at walls
  • Flat grade: No slope allows water to pool against foundation
  • Soil against siding: Creates moisture damage and pest entry points
  • Mulch piled high: Holds moisture against foundation, attracts termites
3

Gutters & Downspouts

10-15 min

Roof drainage systems collect thousands of gallons annually. Properly functioning gutters and downspouts direct this water safely away from the foundation.

Gutter Condition

Downspout Assessment

Downspout Discharge

Discharge Guide: Downspouts should discharge minimum 4-6 feet from foundation onto grade that slopes away. Underground drainage pipes should daylight well away from foundation or connect to storm sewer where permitted.
4

Surface Drainage Systems

10-15 min

Surface drainage features direct water across the property. Swales, catch basins, and channel drains manage water flow and prevent accumulation near structures.

Swales & Drainage Channels

Catch Basins & Drains

French Drains & Subsurface

5

Driveways & Walkways

10-15 min

Hardscaped surfaces affect drainage patterns. Improperly sloped driveways and walkways can direct water toward foundations or create ponding areas.

Driveway Drainage

Walkways & Patios

Common Hardscape Drainage Defects
  • Driveway slopes to garage: Directs water into garage—trench drain needed
  • Settled sidewalk at foundation: Creates channel directing water at house
  • Patio drains toward house: Common after settling—re-grading or drain needed
  • Gaps at foundation: Allow water entry—should be sealed
6

Erosion Assessment

10-15 min

Erosion indicates active drainage problems and can undermine foundations, expose utilities, and damage landscaping. Identifying erosion patterns reveals water management issues.

Erosion Indicators

Foundation Area Erosion

Slopes & Hillsides

Pro Tip: Erosion at downspout discharge points is extremely common and indicates the need for splash blocks, extensions, or underground drainage. This is one of the easiest drainage improvements to recommend.
7

Window Wells & Below-Grade

5-10 min

Below-grade areas require special drainage attention. Window wells, stairwells, and basement entries can collect water and allow intrusion if not properly drained.

Window Well Inspection

Below-Grade Entries

8

Sump Pump & Interior Drainage

5-10 min

Interior drainage systems handle water that reaches the foundation. Sump pumps are critical components requiring inspection for proper operation.

Sump Pump Assessment

Interior Drainage Signs

Sump Pump Red Flags
  • Pump doesn't activate: May be failed, unplugged, or stuck float—immediate concern
  • Discharge at foundation: Water recycles back to sump—defeats purpose
  • No check valve: Water drains back to pit after each cycle
  • No backup system: Power failure during storm leaves basement unprotected
9

Documentation & Reporting

5 min

Final Documentation

Common Drainage Inspection Mistakes to Avoid

✗

Not Walking Full Perimeter

Drainage problems vary around foundation. Check all four sides—the worst issues are often in less visible areas.

✗

Ignoring Downspout Extensions

Short downspouts dumping at foundation are extremely common. Always check discharge distance from foundation.

✗

Missing Negative Grade

Subtle negative slopes are easy to miss. Get eye level with the grade to accurately assess slope direction.

✗

Skipping Sump Pump Test

Always test sump pump operation. A non-functioning pump is critical—owners often don't know it's failed.

✗

Forgetting Window Wells

Window wells collect water and debris. Check every well for drainage issues and accumulation.

✗

Not Connecting Interior Signs

Water stains in basement indicate exterior drainage failure. Connect interior evidence to exterior causes.

Drainage Issue Severity Reference

Issue Found Severity Recommended Action
Negative grade at foundation High Re-grade to slope away minimum 6" per 10 ft
Downspouts discharging at foundation High Add extensions minimum 4-6 feet from foundation
Failed sump pump High Replace pump immediately, consider backup
Standing water in window wells High Clear drains, add covers, improve drainage
Gutters overflowing/damaged Medium Clean, repair, or replace gutter system
Erosion at discharge points Medium Add splash blocks or underground drainage
Flat grade (no positive slope) Medium Add soil to create positive slope away
Minor settlement at walkways Low Monitor, mudjack, or re-pour if worsening

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Frequently Asked Questions

How much should the ground slope away from the foundation?
The minimum recommended slope is 6 inches of fall over the first 10 feet from the foundation (approximately 5% slope). This ensures water flows away from foundation walls rather than pooling against them. Steeper slopes are even better where landscaping allows.
How far should downspouts extend from the foundation?
Downspouts should discharge a minimum of 4-6 feet away from the foundation onto grade that continues to slope away. Underground drainage pipes are ideal, discharging water even farther from the structure. Splash blocks alone are often insufficient without extensions.
What causes most basement water problems?
Approximately 90% of wet basement problems result from surface water not being controlled—specifically improper grading and inadequate gutter/downspout management. Correcting these exterior drainage issues often eliminates basement moisture without expensive interior waterproofing.
How do I test a sump pump?
Test sump pumps by slowly pouring water into the pit until the float activates the pump, or by manually lifting the float switch. The pump should activate, discharge water through the pipe, and shut off when the water level drops. Also verify the discharge location is away from the foundation.
What is negative grade and why is it a problem?
Negative grade means the ground slopes toward the foundation rather than away from it. This directs rainwater and runoff directly against foundation walls, increasing hydrostatic pressure, promoting water infiltration, and accelerating foundation deterioration. It's one of the most common and serious drainage defects.
Should I inspect drainage during dry weather?
Yes, drainage can be evaluated in dry weather by assessing grades, checking gutter condition, and looking for erosion evidence. However, inspecting during or after rainfall reveals active problems—standing water, overflow, and saturated areas—that may not be visible otherwise. Note weather conditions in your report.