How to Select Different Types of Retaining Walls for Every Site
Why the right retaining wall type matters
Choosing the correct retaining wall doesn’t just come down to personal taste, because retaining walls are structural safeguards for your land and everything on it. Undersized or poorly suited walls can lead to erosion, hydrostatic pressure, or sudden collapse, putting people, property, and budgets at risk.
Every project should begin with a careful assessment of soil class, groundwater levels, slope angle, seismic zone, and live loads such as traffic or stored materials. Your engineers will translate these factors into earth-pressure calculations that will guide material choice and wall geometry. By involving a professional early, owners typically save 10-15% on rework and contingency costs while gaining the peace of mind that comes from knowing that the wall will pass code reviews the first time round.
Need a deeper dive into site analysis? Check out our rundown of structural engineering services and the importance of thorough soil investigation and geotech testing. Otherwise, read on to learn more about the different types of retaining walls.
Gravity (mass) Walls: Solid, Simple, and Durable
Gravity walls resist lateral earth forces with their own mass. Built from reinforced concrete, stone masonry, or large interlocking blocks, they’re the go-to solution for heights up to about three meters, as long as there’s enough bearing capacity. Because the entire cross-section is being compressed, there are minimal reinforcement demands, keeping material costs low and construction straightforward.
Key design points to consider include:
Footprint and setback: A broad base (of around half the height of the wall) shifts the centre of gravity toward the slope, boosting stability.
Drainage: Perforated pipes, weep holes, and free-draining backfill can be used to relieve hydrostatic pressure.
Load limits: Heavy surcharges (e.g. from traffic or storage yards) might push designers toward cantilever or anchored systems instead.
Despite their bulk, modern modular units let architects blend textures and colors that complement surrounding landscapes. That’s why gravity walls are still the go-to choice for budget-friendly, low-maintenance retaining walls when space isn’t at a premium.
Cantilever and Counterfort Walls: High-Performance Engineering
When site space is tight but you still need to reach 3-6 meters of height with your retaining wall, a cantilever wall is your best bet because it delivers maximum strength from a slender profile. The reinforced concrete stem works like an inverted “L,” giving your retaining wall a broad footing. Engineers fine-tune heel vs. toe length, rebar spacing and key depth so that the wall can counteract the load that’s placed upon it.
If you need to go taller (6-9 meters) without blowing the budget, you can use counterfort ribs. These are typically spaced at roughly 60-80% of the wall’s height and tie the stem to the footing, reducing stem thickness by up to 40%, contributing to lower concrete volumes and easier placement.
Design essentials for cantilever and counterfort walls include:
Subgrade prep: A uniformly compacted granular base to avoid differential settlement.
Drainage: Filter fabric, perforated drain pipes and weep holes every 1.5 meters to keep hydrostatic pressure in check.
Seismic and surcharge checks: Finite-element modelling ensures that the wall meets KS 02/T/2024 seismic provisions and live-load demands.
Interested in learning more? Click here to explore similar tall-wall solutions amongst our commercial structural design projects.
Anchored and Sheet-Pile Walls: Slim Solutions for Urban and Waterfront Sites
Anchored and sheet-pile systems offer a blend of high capacity and minimal footprint for dense urban lots, basement excavations and quay walls.
Anchored Soldier-Beam/Tie-back Systems
For this kind of system, steel H-piles or soldier beams are drilled or driven, then braced with strand anchors, helical anchors, or micro-piles that lock into the strata 6-12 meters behind the wall line. Pre-stressing the anchors counteracts active earth pressure, allowing a 300 mm thick wall to safely retain 8 meters or more. Vibration monitoring protects nearby structures, while real-time load cells verify anchor performance.
Sheet-Pile Walls
For sheet-pile walls, interlocking steel, vinyl, or composite sheets are vibrated or pressed to design depth, creating a continuous watertight barrier. This makes them ideal for cofferdams, river embankments, or contaminated soil cut-offs. A waler-and-tie-rod system adds lateral resistance without widening the section. Sheet piles can be extracted and reused, lowering their lifetime CO₂ emissions compared to cast-in-place options.
Key considerations for anchored and sheet-pile walls include:
Corrosion protection: Epoxy-coated or cathodic systems in saline zones can help to prevent erosion.
Groundwater control: Well-point dewatering behind the sheets can prevent issues with groundwater.
Permits and neighbors: You and/or your engineer will need to consider environmental approvals and party-wall agreements.
Mechanically Stabilized Earth (MSE) and Modular Block Walls
When a site calls for tall, flexible, and visually appealing solutions, it makes a lot of sense to turn to MSE walls and segmental modular block walls.
MSE systems layer compacted granular backfill with geogrid or steel strips, creating a composite “reinforced-soil” mass that behaves like a gravity wall, but with a much slimmer face. This allows them to climb to heights up to 12 meters (and beyond, with staged construction), making MSE ideal for highway embankments, rail cuttings, and industrial yards.
There are a number of advantages to MSE systems, including:
Speed: Pre-cast panels or dry-stack blocks can be installed quickly, trimming programme time by ~30% versus cast-in-place systems.
Curves and tiers: Radius walls and terraced landscaping are simple with modular units.
Resilience: Minor settlements dissipate through the reinforced fill without cracking.
Here are the design essentials you’ll want to consider:
Backfill quality: Non-plastic, angular aggregate maximizes pull-out resistance.
Drainage: Blanket drains and heel outlets keep water pressure at bay.
Facing connections: Stainless or hot-dip-galvanized hardware can withstand tropical humidity.
Keen to know more? Explore the basics in our slope and embankment reinforcement guide, then find out how our retaining wall inspection service can provide ongoing maintenance and support.
Specialty and Hybrid Retaining Walls
Some projects require you to go above and beyond standard wall types, often due to challenging geology, heritage-site aesthetics, or ultra-tight footprints. Here are four of the proven systems our engineers deploy when “off-the-shelf” won’t cut it:
Gabion baskets: Stone-filled wire cages flex with minor ground movement and drain naturally, making them ideal for floodways, creek realignment, and mine haul-roads. They green over time as vegetation colonizes the voids, softening the look of heavy infrastructure.
Timber crib walls: Interlocking, pressure-treated timber frames create a rustic façade prized that works great in parklands and on golf-courses. They’re lightweight, have a low embodied-carbon footprint, and infill with free-draining stone for stability.
Soil-nail and shotcrete walls: For over-steep cuts or basement shoring, a grid of tensioned steel bars is drilled into the ground, then strengthened with reinforced shotcrete. This method preserves valuable real estate because the finished wall is super thin, often less than 300 mm.
Hybrid toe-gravity and geogrid backfill: When toe room is scarce but height is substantial, we sometimes pour a short gravity toe at the base to counter sliding and then reinforce the upper backfill with geogrids. This allows us to trim concrete volume while keeping wall performance high.
All of our speciality solutions begin with a whole-slope stability analysis (we use PLAXIS) to ensure safety. Most architects seek a specific finish, but our team can specify textured shotcrete or sculpted form-liners that imitate natural stone without sacrificing the strength of reinforced concrete.
Planning a unique façade? Browse our architectural retaining wall finishes or request a consultation with the Exactus Design team.
How Exactus’s engineers choose the ideal wall
Great retaining-wall design requires a mixture of science, experience, and local know-how. Our process compresses hundreds of variables into a clear set of recommendations so that you can build with confidence.
Here’s how we do it:
Site reconnaissance and data capture: We document topography, drainage paths, utility corridors, and any signs of slope instability, then commission targeted geotechnical borings to understand the soil.
Load definition: We quantify, measure and define everything, from active and passive earth pressures, groundwater levels and traffic surcharges to seismic coefficients and planned architectural loads.
Concept filtering: Using our in-house decision matrix (which measures factors like cost, constructability, aesthetics and embodied carbon), we narrow the options down to the two or three wall types that most suit the brief.
Detailed modelling: Finite-element checks verify sliding, overturning, global stability, facing pull-out, and long-term deflection. Drainage, erosion control, and back-of-wall waterproofing are integrated at this stage, as opposed to being tacked on when it’s too late.
Permitting and tender support: All of our plans carry our structural stamp, and we support you throughout the lifecycle of the project. That means we’ll liaise with county engineers, review contractor RFIs, and stay engaged until the wall passes final inspection.
Want to know more about us? Click here to meet our structural engineers and geotechnical specialists.
From Consultation to Completion
Every retaining-wall commission follows a four-step client path which is designed to eliminate surprises and keep schedules tight. Here’s what that looks like:
Step 1: Discovery call and photo review: Send us site photos, a rough grading plan, the height the wall needs to be and your style wishlist. We’ll look for any red flags and outline the scope of the survey and soil testing.
Step 2: Concept and budget alignment: You’ll receive a concise options brief within ten working days. That will cover wall type, preliminary sketches, projected costs, and a timeline for the construction. You choose the direction; we refine the details.
Step 3: Final design and construction support: At this point we’ll issue a full structural package that’s ready for contractor bids and which covers wall geometry, reinforcement schedules, drainage details, material specifications and more. We perform milestone inspections and issue field reports during construction so that builders stay on spec.
Step 4: Completion and certification: A final walk-through confirms quality workmanship and ensures that drainage and safety factors have been effectively dealt with. We then issue a compliance certificate plus a maintenance guide to protect your investment for the decades to come.
Ready to move from concept to reality? Reach out to us today for a no-obligation slope review, and let’s secure your site the Exactus way.
The bottom Line
Every site is different, and choosing the wrong retaining wall can lead to costly repairs, water damage, or even structural failure. Whether you're dealing with a steep slope, soft soils, or space limitations, Exactus Engineering offers personalized, engineer-stamped solutions that are tailored to your landscape.
From the first consultation to the final inspection, our licensed team ensures that every detail is covered with precision, from drainage to design and implementation. With us, you get the peace of mind that comes from knowing your wall is built to last and that it meets all local codes and safety standards.
