Wall-to-Wall Article Summary
Looking for a quick overview? Here are the key takeaways:
Retaining wall projects may need engineering depending on site conditions. Taller heights, wall reinforcement, loading and drainage are a few key design considerations.
Engineered retaining walls help prevent wall failures, drainage problems and expensive repairs to ensure stability, proper drainage and long-term performance.
Retaining wall engineering helps meet local compliance and standards, improves safety, and can saves construction time and costs for residential and commercial projects.
Retaining walls are often looked at as just another backyard or parking lot landscaping product. In reality, they are structural systems that are capable of, and responsible for, much more. Retaining walls hold back significant soil loads, water pressure, surcharge loads, and in some cases roadways, parking lots and buildings.
Why Engineering Matters for Retaining Wall Projects
Our retaining wall experts answer plenty of common inquiries each day, but one question comes up more than any other. It’s not only DIY homeowners that ask while planning their first retaining wall, seasoned contractors and landscape architects do too. So, let’s dive into it.
Does my retaining wall project need engineering?
For residential walls, commercial projects, shoreline applications, or DOT infrastructure work, proper engineering is critical to safety and long-term performance. Both segmental retaining walls (SRWs) and big block retaining wall systems deliver proven solutions, but every project site is different. Soil and loading conditions, hydrostatic pressure, wall height, seismic requirements, and other factors all impact wall designs and their construction.
Each Retaining Wall Design Is Different
One misconception about retaining walls is that they are looked upon as Lego blocks that can be stacked and clicked together as a structure, without considering site conditions behind and around them. Two walls that appear identical may require completely different engineering based on what’s below grade or behind the wall.
Engineering at different stages of a retaining wall project can help evaluate:
- Soil conditions
- Reinforcement requirement under acting surcharge loads
- Drainage requirements
- Foundation preparation
- Seismic and wind loading (if applicable)
Without proper engineering, walls can experience considerable movement and settlement, drainage failures, bulging, or in worst-case scenarios, complete structural failure. While engineering may add construction expenses, it ensures safe, secure solutions that prevent costly, and potentially disastrous, retaining wall failures.
Some retaining wall systems, including MagnumStone, offer free comprehensive retaining wall design software. This empowers wall designers to creatively customize retaining wall plans, backed by extensive input options and analysis features. The software’s intuitive system, accuracy and block counts provide efficient designs, plus quick layouts and block counts.
Why Engineering Is Important for Segmental Retaining Walls
Segmental retaining walls (SRWs) are engineered systems consisting of smaller block units. Shorter gravity walls (up to 4 ft / 1.22 m tall) for gardens and raised patios may not require reinforcement, largely relying on the mass of the blocks. Taller walls or those supporting additional loads typically need geogrid reinforcement and engineered designs.
Engineering for SRW designs helps determine:
- Geogrid lengths and elevations
- Wall embedment requirements
- Sliding and overturning resistance
- Bearing capacity and proper drainage
- Global stability
A properly engineered SRW system improves safety and performance but also optimizes construction costs by reducing unnecessary excavation or overbuilding.
Big Block Retaining Wall Systems Still Require Engineering
Big block wall systems, also known as precast modular blocks (PMBs), offer major engineering advantages for retaining wall projects. Their mass and ability to build taller gravity walls with less invasive reinforcement that minimizes wall depths, maximizing usable land. However, just because a block is large and heavy does not mean that reinforcement and engineering is not required.
Big block retaining wall systems are commonly used for:
- Commercial developments and industrial sites
- Shorelines and waterfront projects
- Heavy and active load applications
- Roadway and DOT infrastructure
- Bridge wing walls, abutments and culvert approaches
Engineering helps determine whether the wall can function as a gravity wall or if reinforcement or hybrid solutions are required. Their engineered designs evaluate bearing pressures, hydrostatic pressure, foundation stability and external loads. Versatile retaining wall systems like MagnumStone offer many reinforcement options, including unidades extensoras de gravedad y geogrid solutions.
Each reinforcement solution has distinct advantages; some are obvious, others are more subtle. Accordingly, engineers can determine the wall design that best fits the specific objectives and unique site conditions of every project. Engineering can often save significant project costs by preventing errors, reducing risks and addressing key design considerations with more precision.
Drainage Is Critical: Where is the Water Going?
Engineers and wall designers fully understand the importance of asking “Where is the water going?” This simple question can help ensure building a retaining wall doesn’t turn into rebuilding a retaining wall. That’s because one of the leading causes of retaining wall failure is inadequate drainage.
Designing and building sufficient drainage is a critical component of retaining walls, no matter the size. Water build-up behind a wall leads to increased hydrostatic pressure and can compromise even the strongest retaining wall systems.
Hollow core block designs like MagnumStone’s act as built-in vertical drainage channels, allowing water to move toward drainpipes quicker. The cores are filled with drainage gravel during installation, filtering and promoting water removal from behind the wall. This reduces risks of debris and sediment restricting the wall’s drainage in the future.
Engineering helps identify necessary considerations for retaining wall drainage:
- Defining drainage aggregate requirements
- Perforated drainpipe placement
- Water management details
- Surface drainage considerations
- Outlet locations
Proper drainage design is critical for SRWs and big block retaining walls, playing a major role in long-term wall performance.
Engineering Helps with Permitting & Liability
Many municipalities require stamped engineering drawings for retaining walls over certain heights or for walls supporting surcharge loads. Requirements vary depending on the project location, wall height, and intended application.
Consulting with local engineers authorized to stamp engineering drawings in your area is strongly recommended. There’s a greater chance they’re familiar with local permits and compliance requirements that can expedite the process, too.
Wall design engineers help your project by:
- Streamlining permitting and project timelines
- Ensuring code compliance
- Increasing insurance, reducing liability
- Improving project confidence
- Providing long-term peace of mind for owners and developers
Check with local municipal or county officials regarding building code, site and design requirements before beginning any retaining wall project.
What Are Preliminary Engineering Designs?
A major advantage of selecting retaining wall systems that offer engineering support is the ability to review preliminary plans. Reviewing preliminary plans early in the project allows time to make design adjustments and evaluate the cost of potential revisions. Wall design engineers can identify and proactively avoid unexpected site and retaining wall challenges before they become issues.
Preliminary engineering designs, also known as take-offs, can help provide:
- Preliminary wall layouts
- Block quantities
- Geogrid estimates
- Budgetary numbers
- Alternative wall solutions
- Construction feasibility review
Involving engineering experts for early-stage support often helps contractors and owners avoid costly changes later in the project. It can also deliver accurate material estimates for block quantities, visual layouts and more efficient project design options.
How Engineering Delivers Value for Retaining Wall Projects
Retaining walls create usable space and can improve property appearance but also need to perform for decades under real-world conditions. Proper engineering is one of the most important parts of ensuring safe long-term wall performance and stability.
Whether building with SRWs or big block retaining wall systems, engineering helps ensure walls are specifically designed with precision for its site conditions. Proper retaining wall engineering is an upfront investment that can save significant time, money, and risk down the road.
For further insight and engineering support for an upcoming retaining wall project, contact MagnumStone’s engineering team today. Our experts look forward to answering your questions!
