Retaining Walls: Engineered, Drained and Built to Hold

What goes on behind the wall

A drainage aggregate zone of clean washed stone directly behind the blocks, giving water a path down rather than pressure against the wall.

A perforated drain pipe at the base of that zone carrying water out to a discharge point, not just into the soil beside the wall.

Filter fabric separating the drainage stone from the retained soil so silt does not migrate in and clog it.

A compacted base of crushed stone below the first course, set below finished grade so the wall cannot slide forward.

None of this is visible when the job is done, which is exactly why it gets skipped on cheap installations.

Height, engineering and permits

Most Pennsylvania municipalities require engineered drawings and a permit for walls above a certain height, commonly four feet, measured from the bottom of the base rather than from the ground you see.

Walls supporting a driveway, a structure or a slope above them carry surcharge loads and may need engineering at lower heights.

Taller retained heights are often better built as tiered walls, which reduces the load on any single wall and usually looks better.

We confirm the requirement in your township before quoting.

• Drainage systems