Rock garden walls should never be straight, but should meander and undulate with an ideal maximum height of 18″ (comfortable seating and visually unobtrusive) tapering to zero at times. The rock walls should be well tamped with moist loose soil and taper slightly back for stability. Dry stacked rock walls should last indefinitely as there is no hydrostatic pressure build up behind them. They naturally weep groundwater. The soil joints between the rocks should be used to plant succulents to further naturalize their look.
Stone retaining walls, on the other hand, must be constructed quite differently. First of all they require a concrete footer reinforced with strands of rebar. These footers should be to code, i.e., below the frost line, extending beyond the wall in either direction and be at least eight inches thick. The actual size of the footer is determined by the size of the wall, which can be any height. Often times these stone walls are backed with a block wall with its webs filled with concrete and rebar. This is not absolutely necessary, however. Whatever the method of construction may be, many walls should have a backfill drainage field of gravel protected from silt buildup with barrier cloth and weep holes at the base of the wall approximately every four feet or so. These don’t have to be ugly PVC pipe, but could instead be just holes in the wall themselves. Neither dry stack nor masonry walls are immune from tree roots which can damage either.
Contact us about designing and building a rock garden for your home.
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