Learn & Understand

Shaping the Ground: Berms, Earthworks, and the Land as Material

A berm — a deliberate mound of soil — treats the earth itself as a design material. Building one puts a homeowner in the ancient tradition of earthworks, the practice of shaping ground for beauty, defense, drainage, and even sound. A pile of fill is, in this light, a small piece of landform architecture.

Earthworks Through History

Moving earth to shape a place is among the oldest human constructions. Ancient peoples raised ceremonial mounds and effigy earthworks; military engineers threw up ramparts and defensive banks; agricultural societies built terraces and irrigation bunds. Long before poured concrete, the raw material of construction was often the ground itself, cut and heaped into intended forms. A garden berm is a modern, modest continuation of that lineage.

Why Build a Mound

A berm does several jobs at once. It creates visual interest and elevation on a flat lot, giving a garden dimension it otherwise lacks. It directs drainage, steering runoff around or away from an area. It screens for privacy, raising a planting bed to block sightlines. And it can buffer noise, putting a mass of soil between a home and a road. Few landscape features are as multipurpose as a well-placed mound.

The Soil Wall of Sound

A berm's noise-buffering ability is real physics. A mound of earth is dense and solid, and it both absorbs sound energy and blocks the direct line of travel from a source to a listener — the same principle behind the earthen and concrete sound barriers along highways. A planted berm between a yard and a busy road can measurably soften traffic noise, doing with soil what a wall does with mass.

Building It to Last

Loose fill settles. Soil heaped up and left will compact under its own weight and with each rain, so a berm built to a target height must be constructed higher, or the fill placed and compacted in layers, to end up where intended after settling. Its profile matters too: a gently rounded mound holds slightly less volume than the triangular cross-section often used to estimate fill, so that approximation errs safely toward ordering a little extra.

Estimating the Fill

To turn a berm's length, base width, and height into a fill volume, use the Landscape Berm Volume Calculator. Source the fill with the Topsoil Calculator, measure the slopes you create with the Slope Grade Percentage Calculator, and plant the finished mound using the Tree Spacing Calculator.