Walls & Grade Work
Retaining Wall Installation in Downriver Michigan
A retaining wall holds back soil to make a sloped yard usable, and it is a drainage structure as much as a stacked one. Walls are priced by the square foot of exposed wall face, and cost rises sharply once a wall crosses the height at which Michigan requires engineered design, because that threshold brings geogrid reinforcement, deeper base work, and permitting into the job.
Retaining walls are the least understood thing we build. From the outside a wall looks like blocks stacked on blocks, which is why they are the element most often built badly by people who should not be building them. What actually holds a wall up is the base beneath it, the drainage behind it, and on taller walls the geogrid running back into the retained soil.
The walls we build fall into two broad groups. Low decorative and seat walls define a patio edge, terrace a garden, or give an outdoor room a boundary you can sit on. Structural walls hold a real grade change, reclaim an unusable slope, or stop soil moving toward a house or a pool.
The two are built very differently, and the honest conversation early on is about which one your site actually needs. A wall that is holding meaningful soil load is a structure, and treating it like a garden feature is how walls end up leaning within a few winters.
What a retaining wall project includes
- Site assessment covering the grade change, soil conditions, and where water currently moves
- A determination of whether the wall requires engineered design under Michigan requirements
- MISS DIG 811 utility locate before excavation
- Excavation for a buried base course, so the wall starts below finished grade
- Compacted aggregate levelling pad, built flat and true across the full run
- Free draining aggregate backfill behind the wall face, with drainage pipe where required
- Geogrid reinforcement layers tied into the retained soil where the design calls for it
- Cap course, backfill, grading, and restoration of the surrounding area
Materials for a retaining wall
- Oberfields segmental retaining wall block, sized to the wall height and application
- Manufacturer specified geogrid where the design requires reinforcement
- Free draining angular aggregate for the drainage zone behind the wall
- Perforated drainage pipe with a real outlet where the wall needs one
- Compacted aggregate levelling pad beneath the buried base course
- Adhered cap units, and matching seat wall caps where the wall doubles as seating
Authorized contractor
We are an authorized Oberfields contractor and build to their published specification for the block being used, including setback, geogrid placement, and maximum unreinforced height. Building a segmental wall outside the manufacturer specification is what voids the product warranty, and it is also how walls end up leaning.
How we build a retaining wall, step by step
Most of a well built wall is invisible once it is finished. The parts you can see are the last day of the job.
Assessment and design decision
We measure the grade change, look at what is above and behind the wall, and find out where water arrives from. That determines the category of wall. Michigan practice treats walls retaining more than 48 inches of unbalanced fill, or walls carrying a surcharge such as a driveway or structure within a defined distance, as requiring engineered design with a safety factor of 1.5. Below that threshold a properly built segmental wall is generally a standard install.
Permits and utility locate
Wall height is the most common trigger for a permit in the Downriver municipalities, and the threshold is not the same everywhere. We confirm with your city rather than assuming. The MISS DIG 811 locate is filed with at least three full business days notice and no more than 14 calendar days ahead, as Michigan Public Act 174 of 2013 requires.
Excavation and levelling pad
We excavate a trench for the base and dig out any unsuitable material behind the wall line. The levelling pad is compacted aggregate, built dead flat and checked across the entire run, because every error in the first course is multiplied by every course above it. The bottom course is set below finished grade, which is what keeps the toe of the wall from kicking out.
Base course
The first course of block is set on the levelling pad and levelled in both directions, block by block, not by eye down the run. This is slow and it is the step that separates a wall that stays straight from one that develops a visible waver by the third course.
Drainage
Free draining aggregate goes in behind the wall face as the courses rise, and drainage pipe is installed where the design requires an outlet. This is the part of a wall that gets skipped most often, and it is the reason most failed walls fail. Saturated soil behind a wall exerts far more pressure than drained soil, and in Michigan that saturated soil then freezes and expands.
Reinforcement and courses
Where the wall needs geogrid, the layers go in at the spacing the design specifies, extending back into the retained soil and compacted over. Courses continue with the block set back or pinned according to the manufacturer specification, and the drainage aggregate and compacted backfill rise together with the wall rather than being filled in at the end.
Caps, grading, and restoration
Cap units are set and adhered, the grade above and below the wall is finished so water runs where it should, and the surrounding area is restored. We leave the site with the drainage working, not just the wall standing.
Frost, saturated soil, and why walls lean
A leaning retaining wall in Michigan is almost always a water story rather than a weight story. Soil that cannot drain holds water, water that cannot escape freezes, and freezing water expands and pushes. Repeat that through a winter of freeze and thaw cycling and the wall moves a little each time until the movement becomes obvious.
That is why the drainage aggregate behind the face and the outlet at the base are not optional extras on our walls. Keeping water out of the retained soil removes both the hydrostatic pressure and the frost pressure at the same time.
The buried base course is the other frost detail. Starting the wall below finished grade means the toe is not sitting where seasonal heave can lift it, and it gives the wall something to push against rather than allowing it to slide forward.
Clay makes all of this harder. Much of the Downriver area sits on soils that hold water rather than shedding it, so on those lots we build the drainage detail more aggressively than a sandy site would need. A wall that would be fine elsewhere in the state can be underbuilt here.
What a retaining wall costs
Retaining walls are priced by the square foot of exposed wall face rather than by linear foot, because a wall twice as tall does far more than twice the work. Height drives excavation depth, the amount of drainage aggregate, whether geogrid is needed, and how much soil has to be moved and replaced behind the face.
The step change in cost happens at the point where the wall becomes an engineered structure. Below that threshold it is a well built standard install. Above it you are adding an engineered design, reinforcement layers, deeper base work, and usually a permit, and the price reflects all of it.
Other things that move the number: whether machinery can reach the wall line, how much material has to be hauled away, whether there is a surcharge such as a driveway or structure above the wall, and whether the wall doubles as seating with a finished cap detail.
We price after seeing the slope, because the two things that matter most, what the soil is like and where the water goes, cannot be assessed from a photo.
Project Gallery
Work we have completed across Southeast Michigan. Every photo is our own.
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Retaining Walls FAQs
Common questions from homeowners planning hardscape projects in Southeast Michigan.
Related services
Got a slope you cannot use?
We will look at the grade, tell you whether it needs a structural wall or a decorative one, and be straight with you about which category you are in before you spend anything.