100 ft × 3 ft retaining wall: materials, cost and layout
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100 ft × 3 ft retaining wall
What a 100 ft × 3 ft retaining wall takes to build: the materials list, when it needs geogrid or an engineer, how long it takes, and what it costs installed.
- 300 sq ft of face
- 552 blocks
- 24.3 tons of stone
Materials for a 100 ft × 3 ft retaining wall
| Item | Quantity | Notes |
|---|---|---|
| Wall face | 300 sq ft | length × exposed height |
| Wall block (6 in × 16 in face) | 552 blocks | includes one buried course and 5% extra |
| Cap units | 79 caps | glued down with concrete adhesive |
| Base: crushed stone (2A modified / crusher run) | 6.2 tons | 24 in wide × 6 in deep trench, compacted |
| Drainage stone (clean #57 / 2B) | 18.1 tons | 12 in wide behind the block, full height |
| Perforated drain pipe, 4 in | 110 ft | at the base of the drainage stone, run to daylight |
| Filter fabric | 600 sq ft | between the drainage stone and the soil |
| Soil dug out | 9.6 cu yd | base trench only; more if the slope has to be cut back |
Quantities use common rules: crushed stone at about 1.4 tons per cubic yard plus 20% for compaction, concrete sand at about 1.35 tons per cubic yard. Your stone yard can convert to their product. Base depths assume normal soil in a freeze-thaw climate; soft or wet soil needs more.
Good to know
- At 3 ft, many block makers want geogrid on clay soil or with a slope or driveway above. Check the chart for your block before you build.
- When a retaining wall fails, it is almost always water, not the block. The drainage stone and pipe in the list above are the part not to skip.
Get a plan drawn for your yard
- Groundwork Design Co., our design studio, draws a 100 ft × 3 ft retaining wall for your actual yard from photos and measurements
- Scaled plan with dimensions, material list and scope any contractor can price
- Single Space plan from $349; retaining wall layout sheet +$350
- We build it ourselves in Clinton, Lycoming, Centre and Union counties
- Fixed price, 33% down, 6-month workmanship warranty
- Closest plan: Garden Wall
- Order the list above, plus 5–10% if your yard has curves
- Call 811 before you dig, two business days ahead
- Rent a plate compactor; compact every 2–3 in of base
Questions
How many blocks for a 100 ft × 3 ft retaining wall?
About 552 blocks of a standard 6 × 16 in face block, plus 79 caps. That counts one course buried below grade and 5% extra.
How much gravel do I need for a 100 ft × 3 ft retaining wall?
6.2 tons of crushed stone for the base and 18.1 tons of clean drainage stone behind the wall.
How much does a 100 ft × 3 ft retaining wall cost installed?
We build a 100 ft × 3 ft retaining wall in central Pennsylvania for about $26,150 ($87 per sq ft of wall face), including excavation, base, materials and cleanup. Prices elsewhere depend on local labor and stone, so the reliable way to price it where you live is a scaled plan and two or three local bids on the same plan.
How long does it take to build?
A two- or three-person crew builds a 100 ft × 3 ft retaining wall in about 7 working days, most of it digging and building the base. A careful DIY build usually takes two to three times as long.
Read next
How deep a retaining wall base should be
Timber vs block retaining walls
Why retaining walls fail
Nearby sizes
50 ft × 4 ft retaining wall
100 ft × 2 ft retaining wall
100 ft × 4 ft retaining wall
60 ft × 3 ft retaining wall
40 ft × 4 ft retaining wall
Retaining wall cost guide: real fixed prices, what moves the price →
Muthler Landscaping & Construction LLC · 913 Bellefonte Ave, Lock Haven, PA 17745 · (570) 397-9800 · PA HIC #PA212584. Installed prices are ours in central Pennsylvania (pricing v1).