Some of the nicer elements in your next landscaping project may be called “hardscaping,” but that doesn’t mean that they are hard to build.
Whether laying paving tiles, placing terrace steps, building a retaining wall, or spreading crushed rock, the trick, local merchants say, is to plan ahead.
“The most critical part is the part you don’t see,” said George Allen, manager of Gagne & Son’s Riverside Drive store, in Auburn. That, he said, means paying careful attention to what goes below and behind your stone features.
“My joke to everybody is that the three most important things are the base, the base and the base,” agreed John Petrocelli, owner of Petro’s ACE Hardware and Landscape Center, in Auburn. “I give that speech 100 times a day.”
Because drainage is so important, crushed rock is vital to any hardscape project.
“You use it a lot,” said Rick Gammon, owner of Gammon’s Landscape Nursery, in Auburn. “You really want it to drain water away, so there’s no freezing and buckling.”
For a base, Gammon recommends using “inch-and-a-half minus” — a mix of rock from fine grains up to pieces 1-1/2 inches across.
“It makes a nice, stable base to set your surface material on,” he said. “It all compacts together, so there are no big air pockets, for settling to happen.”
For use as a mulch, or a “drip strip” around the home, Gammon said 3/8- to 3/4-inch crushed rock works best. Also made locally is crushed brick which, being made of clay, aids moisture retention of dressed plants, in addition to adding a dash of color.
Although more expensive, river rock is best for areas where bare feet may tread, given its worn, rounded edges.
“Vermont is the closest state that allows people to mine rock out of river beds, so, transportation escalates the cost,” said Gammon.
A top-dressing of any kind of stone should be no deeper than three inches, said Gammon. Any more than that may damage underlying root systems. But whatever type is used, don’t forget to lay landscape fabric beneath it, said Gammon. Don’t use plastic sheets or felt material, he warned. Instead, be sure to lay down a purpose-made woven mesh, porous enough to let water drain through, but solid enough to block weeds.
“Make sure you overlap the seams,” said Gammon, “because if you leave any opening at all, any little pucker, the weeds will pop right up through.”
Allen also stressed the importance of using crushed rock for drainage. Too often, he said, people backfill retaining walls with the dirt they’ve excavated. That, he says, causes cracks at frost time.
“If you live in Maine, the ground is going to move,” he said. “You have to get rid of the water to get rid of your troubles.”
Although soil is fine fill for a foot-high garden wall, said Allen, crushed rock, and maybe even a perforated drainage pipe, should be buried beneath the top soil behind any retaining wall. If the wall gets near four feet in height, merigrid — a type of rebar mesh — should be used. The bars are set between rows of the natural-finish concrete blocks used for wall construction and extend into the earth, through layers of base material. That way, Allen said, when frost comes, the land moves with the wall, instead of against it.
With a base firmly in place, actual construction is fairly simple, said Allen. “The beauty of it is that, if you can follow a tape measure, you can do it yourself. Just make sure the first course of blocks is level, because every other course will follow the path of the first.”
Water also figures into the pre-planning needed to lay terrace steps, said Matt Engleman, general manager of American Concrete Industries, in Auburn. It’s important, he said, to angle step platforms down 1/8 of an inch. This lets rainwater and spring melt drain off, but is a slight enough pitch that it doesn’t affect use.
Risers should be the standard 7-1/2 inches used for all steps, said Engleman. Varying step height may create a nice aesthetic, he said, but it’s sure to send someone tumbling.
The cast-concrete terrace steps used by American Concrete are single risers, stacked one on top of the other, with long platforms that, like merigrid, are buried to create a solid whole which moves with the surrounding environment.
“It seems like steps really suffer in landscaping,” said Engleman. “A lot of times people use rocks and fieldstone, or railroad ties, so they end up with steps that look great, but end up being really scary after the first winter.
“Whatever material people use for their steps, they need to think about how it’s going to change over time, so that it stays safe,” said Engleman.
“The beauty of pavers speak for themselves,” said Petrocelli, adding that the choice of color and style is almost limitless.
“What is underneath the product determines how long what’s on top will stay looking nice,” he said. “If installed correctly, it’s physically impossible for anything to ever grow up through it and you can plow right over it in the winter.”
Petrocelli said the key to building a base for pavers is to “go deep enough so everything moves together.” The base should be six-to-12 inches of crushed gravel, highly compacted and topped with an inch of masonry sand, he explained. Pavers should be angled for drainage. The polymer sand swept between them makes a patio move as one unit and prevents grass from seeding between individual pavers.
“If you have your base done right, your children could almost lay the pavers,” said Petrocelli, “and, if I gave you four screwdrivers, a hammer and 20 minutes, you wouldn’t be able to dig one paver out.”