Choosing a Retaining Wall System

Every wall system has a rated height, and that is where the decision starts

A segmental retaining wall system, whether it is Lenza, Munich, Stonegate, G-Force, or Regal Stone Pro, is engineered and rated to a maximum height for gravity construction, meaning the block's own weight and interlock hold it up with no reinforcement behind it. Go past that rated height without adding reinforcement and the wall is carrying more soil pressure than its gravity design accounts for. Before choosing a system, know the actual height the finished wall needs to reach, retaining walls are almost always measured from the bottom of the buried base course to the top of the cap, not just the visible face above grade, because a wall that looks like three feet of exposed block might be closer to four feet of total retained height once the buried courses are counted.

Geo-grid: what it does and why skipping it catches up with you

Geo-grid is a reinforcing mesh laid horizontally between courses of block and extended back into the compacted soil behind the wall, tying the wall face to the reinforced soil mass behind it rather than leaving the wall to resist all the soil pressure on its own. Once a wall's height exceeds its gravity-only rating, geo-grid is not optional extra strength, it is the thing that makes the taller wall structurally sound at all. A wall built past its rated height without geo-grid can look fine the day it is finished, the block is sitting where it was set and the face looks straight.

The soil pressure behind it has not gone anywhere though, and freeze-thaw cycles and saturated soil through a wet winter push on that face every season. A wall missing the reinforcement it needed usually does not fail all at once, it bulges gradually, a course or two starts leaning out of plane, and by the second winter the lean is visible from the street. That is the geo-grid question showing up two years after the install, not two weeks after.

Drainage stone behind the wall

Retaining walls need clean, free-draining aggregate immediately behind the block, not native soil packed right up against the back face. Without it, water saturates the soil directly behind the wall after rain, and saturated soil is dramatically heavier and exerts far more lateral pressure than dry, well-drained soil does. That added hydrostatic pressure is a major driver of wall failure that has nothing to do with the block itself. A drainage stone layer, paired with a perforated pipe at the base of the wall to carry water out and away, keeps that pressure from building up behind the face in the first place.

Field block, corner units, and cap units are three different line items

When you are pricing a wall, the field block that makes up the bulk of the straight wall face is only part of the order. Corner units are shaped specifically to turn a clean, interlocked corner without cutting standard block, and cap units finish the top course with a flat, weather-shedding surface that standard field block is not designed to be the top of. Leaving corner and cap units out of an estimate and pricing only field block is one of the more common ways a wall budget comes up short partway through the project. Count linear feet of field wall, count every corner, and count linear feet of cap separately before pricing the job.

What to bring to the counter when pricing a wall

• The total retained height, measured from the base of the buried footing to the top of the finished cap, not just the visible face.
• The total linear footage of wall, broken out by any corners or curves.
• Whether the wall is holding back a slope, a flat yard cut, or something with additional load behind it like a driveway or a structure.
• Which system you are leaning toward, Lenza, Munich, Stonegate, G-Force, or Regal Stone Pro, since their rated heights and unit sizes differ.

Wall block runs $6.25 to $91.50 depending on the unit and system. We stock the field block, corner units, cap units, geo-grid, and drainage stone this kind of project needs, and can talk through height and reinforcement requirements at the counter before you commit to a system.