Groundwork Design Co. / Online retaining wall design
Online retaining wall design for walls that stay standing.
Wall layout, heights, drainage, base and a block count, drawn by a crew that builds segmental walls. We flag anything that needs an engineer before you pay for it.
A retaining wall is the one piece of a yard that can fail badly. Walls lean, bulge and fall over for the same few reasons: no drainage, a weak base, not enough block buried, or too much load behind them. Our online retaining wall design service lays your wall out the way our crews at Muthler Landscaping & Construction build them in central Pennsylvania, and we draw it for homeowners anywhere in the U.S.
When a wall needs an engineer
Most U.S. building codes treat walls over about 4 feet tall (measured from the bottom of the footing to the top of the wall) as structures that need an engineered design and often a permit. The same goes for shorter walls that hold up a surcharge: a driveway, parking area, a slope above, or a building. Rules vary by town, so check with your local building office.
We are designers and builders, not engineers. We lay out your wall, flag anything that needs an engineer, and give the engineer and your contractor a clean plan to start from. We never stamp drawings.
What goes into a retaining wall plan
- Layout and length, including corners, curves, returns and where the wall ends into the slope.
- Exposed height along the wall and where it steps up or down to follow grade.
- Buried course. Block makers typically call for at least 6 inches, or about an inch per foot of wall height, below finished grade. We follow the manufacturer's guide for the block you choose.
- Base. A compacted crushed-stone leveling pad, usually about 6 inches thick, under the first course.
- Drainage. Clean drainage stone behind the block and a perforated pipe at the base that runs to daylight. This is what keeps water pressure off the wall.
- Geogrid layers and lengths where the height calls for them, per the block maker's charts.
- Caps, steps and transitions, plus a material list: block count, caps, base and drainage stone, pipe and grid.
What's on the plan
Which sheets you get depends on the package. This is the same sheet list as our design packages. Wall sections and the quantity takeoff are Build-Ready sheets.
| Sheet | What it shows | Single Space $349 | Full Yard $895 | Build-Ready $1,795 |
|---|---|---|---|---|
| L-1 | Site plan: layout, sizes, materials and plants on one scaled sheet | Included | Included | Included |
| L-2 | Hardscape layout: every patio, walk, step and wall dimensioned | — | Included | Included |
| L-3 | Planting plan with plant schedule, sizes and spacing | List | Included | Included |
| L-4 | Grading and drainage concept: slopes, swales, downspouts, where water goes | — | Included | Included |
| V-1 | 3D views of the finished yard | — | — | Included |
| D-1 | Construction details: base sections, edge restraint, step and wall sections | — | — | Included |
| Q-1 | Quantity takeoff and bid scope: square feet, tons, block count, linear feet | — | — | Included |
Adding a wall to a bigger plan? The retaining wall layout sheet is +$350 at checkout. Our plans are design drawings, not engineered or stamped. A wall over 4 feet or a wall holding up a driveway gets flagged for an engineer on the plan.
Terraced walls instead of one tall wall
Two short walls usually cost less and look better than one tall one, and they may keep you under the height where engineering is required. A common guideline is to set the upper wall back at least twice the height of the lower wall so it doesn't load it. If the terrace is tighter than that, the walls act as one tall wall and need to be designed that way. Terraces also give you planting beds, a flat lawn or a patio level.
Choosing a wall block
Segmental concrete block is the standard for residential walls: it interlocks, sets back slightly with each course, and has published design charts. Natural stone walls look great but are harder to engineer and slower to build. Timber walls are cheap up front and rot out. We design around block that's sold near you.
Retaining wall mistakes we tear out
- No drainage stone or pipe behind the wall.
- Block set on dirt or a thin, uncompacted base.
- First course not buried, so the wall kicks out at the bottom.
- Downspouts or a slope dumping water right behind the wall.
- A driveway or parking pad added above a wall that wasn't designed for it.
- One tall wall where two short terraces would have worked.
What online retaining wall design costs
A single wall with its layout is our Single Space package, $349. Adding a wall to a larger plan is the retaining wall layout sheet, +$350. Whole-yard plans with walls, grading and drainage are Full Yard, $895, and Build-Ready, $1,795 adds wall sections, construction details and a quantity takeoff. Central PA homeowners can get an instant installed price range in our hardscape designer.
Free planning guides
Planning it yourself first? These guides come from the crews who build this work: real sizes, heights and drainage details, with our sample plans as examples.
- Retaining wall ideas: 20 options with the height each works at, a relative cost and how it fails.
- Retaining wall design basics: base, drainage, geogrid and when code calls for an engineer, with a worked example.
- Retaining wall drainage: stone, pipe, outlets and weep holes, plus fixes for a wall that holds water.
- Segmental retaining walls: how dry-stacked block works, height limits and when geogrid is needed.
- How long retaining walls last: lifespans by wall type and the signs a wall is near the end.
- Terraced backyard ideas: tier math, the 2× spacing rule and 11 designs.
- Sloped backyard ideas: 15 ways to use a hill, sorted by steepness.
More reading from our crew
- Why Retaining Walls Fail (and How to Build One That Lasts 30+ Years)
- Best Interlocking Retaining Wall Blocks Compared (Major Brands)
- Allan Block vs. Versa-Lok: A Complete Guide to Retaining Walls in Pennsylvania
- Retaining Wall Maintenance: How to Keep Your Wall Strong and Long-Lasting
- LibertyStone Fortus Square Foot Block Retaining Walls – A Comprehensive Guide
Questions
How tall can a retaining wall be without an engineer?
In many U.S. towns, walls up to about 4 feet (bottom of footing to top of wall) with nothing heavy above them don't need an engineered design. Taller walls, or walls holding up a driveway, slope or structure, usually do. Check with your local building office.
Can you design a retaining wall next to my driveway?
We can lay it out and show how it fits the site, but a wall holding up a driveway carries vehicle load and needs an engineer. We flag it on the plan so you and your contractor know before bidding.
What makes a retaining wall fail?
Water pressure behind the wall is the most common cause. Walls also fail from weak bases, too little block buried, or loads above the wall that it wasn't designed for. Good drainage stone, a drain pipe to daylight and a compacted base prevent most failures.
Do you use a specific block brand?
We design around segmental block sold near you and follow that manufacturer's installation guide for buried depth, setback and geogrid.
Can I build the wall myself from your plan?
Short garden walls, yes, if you follow the plan and the block maker's guide. For taller walls or anything that needs an engineer, hire a contractor experienced with segmental walls.
Are your wall plans engineered or stamped?
No. We're a design studio run by a PA-registered, insured construction company. Our plans are design drawings, not engineered, stamped or survey drawings. If a wall needs an engineer, like a wall over 4 feet or a wall holding up a driveway, we flag it on the plan so you know before you bid it out.
Which package do I need for a retaining wall?
A single wall with its layout is Single Space, $349. Adding a wall to a larger plan is the retaining wall layout sheet, +$350. Whole-yard plans with walls, grading and drainage are Full Yard, $895, and Build-Ready, $1,795, adds wall sections, construction details and a quantity takeoff.
Do you need to see my slope in person?
No. Photos, a walk-around video and your measurements are enough for most yards. For steep lots we may ask for a few spot heights; our photo and measuring guide shows how to get them with a string and a level.
What if I want to change something on the plan?
Every package includes revision rounds: 1, 2 or 3 depending on the package. Extra rounds are $150 each.
Get a wall plan your contractor can build.
Flat price, paid up front. Single Space $349 · Full Yard $895 · Build-Ready $1,795.