Slope & Grade Calculator
Calculate slope percentage and determine if a retaining wall may be needed.
Results
Slope
20.0%
Grade Ratio
1:5.0
Angle
11.3°
Steep Slope
Terracing or drainage solutions may be recommended for this slope.
Methodology & Notes
Slope (%) = (rise / run) x 100. As a general rule, slopes above 30% benefit from a retaining wall for stability and erosion control. Slopes of 15-30% may need terracing solutions. Final assessment depends on soil type and drainage conditions.
Get an Accurate Free Estimate
These calculators provide rough estimates. For an exact price, call us or send photos of your project.
“Before any landscaping project in Montreal, I check the grade first. Poor drainage toward the foundation is the hidden cause behind most basement water problems I see — fixing the slope is cheaper than waterproofing your foundation after the fact.”
How to use this tool
Measure the horizontal distance (run) and the vertical height difference (rise) across your yard or the area of concern. Enter both values and the calculator computes the slope as a percentage, ratio, and degree angle. It also indicates whether a retaining wall may be recommended based on the steepness. Slopes above 33% typically require engineered retaining walls for safety and erosion control.
Why it matters
Understanding your yard's slope is critical before starting any landscaping or construction project. Quebec building codes require proper grading away from foundations to prevent water infiltration. Slopes that are too steep cause soil erosion, make lawn maintenance difficult, and can undermine structures over time. A slope analysis helps determine whether you need a retaining wall, terracing, or simple regrading, each with very different cost implications for your Montreal property.
Frequently Asked Questions
What slope requires a retaining wall in Quebec?
In Quebec, slopes exceeding 33% (a 3:1 ratio) typically require a retaining wall for erosion control and structural stability. Walls over 4 feet high need engineering plans, and walls over 6 feet require a building permit from your Montreal borough.
How do I measure the slope of my yard?
Place a level board horizontally from the high point. Measure the horizontal distance (run) and the vertical drop (rise) at the end. Divide rise by run and multiply by 100 for the slope percentage. A 2% slope away from your foundation is recommended in Montreal for proper drainage.
How much does regrading a yard cost in Montreal?
Regrading a Montreal yard costs $1,000 to $5,000 depending on the area and soil volume needed. Simple regrading for drainage correction is on the lower end, while major grade changes requiring retaining walls run $5,000+. Call Montréal Paysagement Pro at 514-900-3867.