Guide · Retaining walls
Slope grading and terracing
A sloped yard is level space you have not claimed yet. Regrading it is also the moment to decide where the whole lot sends its water.
Read the grade first
Terracing breaks a single tall retaining wall installation into two or three shorter walls. Deciding how many starts with three measurements. Find the total fall, the horizontal distance it happens over, and the fixed points.
Fixed points are levels that cannot move. Typical examples are the rear door threshold, the top of the driveway, an existing patio, the lot line, a mature tree's root zone and a neighbour's grade. Everything between them is open to design, and the aim is to fit usable level ground there with as little structure as possible.
Cut and fill
Moving soil is cheaper than retaining it. Shave the high side, place that material on the low side, and meet at a gentler grade with no wall at all.
This only works with a modest fall, enough run to spread it, and fill compacted in lifts. Loose fill keeps settling for years and drags down anything built over it. When the new face would be steeper than the soil can stand, walls enter the conversation.
Terracing
Where cut and fill cannot absorb the fall, the usual answer is several short walls rather than one tall one. Each wall creates a level, and planting fills the step between.
Requirements for reinforcement, engineering and permits rise quickly with height, so shorter walls tend to stay simpler. Municipal thresholds vary, so confirm with the municipality where a wall sits relative to them. Visually, terraces read as a garden, while one tall face reads as infrastructure.
The limit is run. Each level needs enough depth to be useful, and a steep drop over a short distance may leave room for only one.
What each level is for
Settle the use of each terrace before building, since use sets the depth. Seating needs the furniture footprint plus circulation. A planting bed can be narrow. Lawn needs enough width to be worth mowing. Terraces sized to whatever the slope allowed tend to go unused.
Then the water
Moving ground changes how the whole property handles rain. Plan it as part of the design so spring does not reveal it for you.
- Intercept upslope. A swale or French drain across the top catches water arriving from above before it reaches new work.
- Pitch every level. Each terrace sheds in a chosen direction rather than wherever it happened to settle.
- Drain behind each wall. Clean stone, filter fabric and a base outlet, as the retaining walls hub describes.
- Find the destination. Collected water must end up somewhere with capacity. If nowhere suitable exists, creating one belongs in the scope.
- Protect the house. On a lot falling toward the building, regrading is the chance to pitch ground away from the foundation. It is often the most valuable part of the work.
Holding the ground afterwards
Freshly regraded soil left bare will erode before roots take hold. Cover it straight away with planting, erosion control matting or a heavy mulch. Pick species for their rooting habit, not for how they look on installation day. This modest step largely decides whether the grading survives its first wet spring.
Site access
Sloped sites are slower to work than flat ones. Getting a machine to the low end, a route for spoil to leave and a place to stage material all become real constraints. A gate wide enough for a compact excavator is especially valuable here. If a new fence is planned, schedule it after the ground work, as the fence replacement guide notes.
Sequence
How a regrade runs
Levels taken
Fall measured, fixed points recorded, and immovable constraints listed before design begins.
Drainage strategy set
Current inflow, future outflow and the capacity of the destination, settled first because it shapes every later step.
Levels designed
Terrace depths sized to each use, with wall heights kept within manageable structural range.
Cut, fill and export
Reusable soil placed and compacted on site; the rest trucked away.
Walls built
Base course below grade, stone and fabric behind, lifts compacted, caps pitched to shed water.
Surfaces and planting
Paving, steps and paths on the levels, then immediate cover on any remaining slope.
Questions
Grading questions
Is it better to terrace a slope or build one tall wall?
Terracing usually wins where there is horizontal room for it. Structural demands such as geogrid, engineering and permits climb steeply with wall height, so two short walls often carry less of that burden than one tall one. A terraced grade also reads as garden, with planting between levels, rather than as a blank retaining face. One tall wall makes sense only when the run is too short to fit more than one level.
Can a slope be regraded without any walls?
Sometimes, and that option deserves a look first. Cut and fill moves soil from the high side to the low side and can flatten a gentle grade with no structure at all. It needs a modest total fall, enough room to spread the transition, and fill that can be properly compacted. Once the resulting face would be too steep to stand, a wall becomes necessary.
Where does the water go once the yard is regraded?
That route must be decided before any soil moves. Regrading alters how the entire lot sheds rain, so runoff that once left at the bottom of the slope will take a new path. The new path needs a destination with capacity, never a neighbour's yard or your own foundation. On many sloped lots, resolving drainage is the most valuable outcome of the whole project.
What happens to the soil that comes out?
Suitable material can go back in as compacted fill on the low side. Anything unsuitable, or surplus, leaves the site. Stockpiling clay on the lawn to deal with later smothers the grass and creates a second removal job.