Retaining Walls

Boulder Walls in St. Louis, MO

On a steep wooded lot in Wildwood, Ballwin or Jefferson County, a block wall can look out of place. Boulder walls use large stone, usually quarried limestone around here, set into the slope and following the ground's own curves and steps. They handle uneven ground well. But each stone still needs a firm bed to sit on and water still needs a way out, so a boulder wall is not just rocks dropped on a hill.

Stone That Follows the Hill

Boulder walls fit the ground a block wall struggles with: steep, wooded, uneven slopes whose grade changes every few feet. Instead of stepping a straight course up the slope, large stones are set into it individually, each seated on the one below and leaning back into the hill. Around St. Louis the stone is usually quarried limestone, which weathers to the same grey as the rock outcrops along the Meramec and in road cuts.

A boulder wall should look natural, but a lot of work goes into it. Every stone is picked and turned so it sits right.

Not Just Rocks on a Slope

The failures we get called about tend to be boulders set straight onto topsoil or loose fill, with nothing behind them to drain water. A stone like that settles, rolls forward and pulls the ones above it down. We cut a firm bed for each base stone, into rock where there is rock, pack crushed stone behind and between the courses, and give the water a way out. On taller boulder walls, geogrid behind the stones can be worth it, as with block.

Heavy stone needs heavy equipment close to the wall, so access is usually the first thing we check. Where a more formal look is wanted, cut limestone is the alternative.

Where Boulders Fit

Boulders are the usual choice on the wooded ridges of Wildwood, the steep rocky lots of Arnold, and hillside back yards in Ballwin. They also work for creek-side edges in Webster Groves, bluff-side lots in Oakville, and larger lots in Chesterfield.

Typical timeline Driven by stone size and how close a machine can get. A narrow wooded access can double the time.

Related Services

Work that usually goes with this one on a St. Louis job:

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  • Drainage priced with the wall, not added later
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(557) 256-7261