How to Build a Rock Wall with Mortar and Line Your Yard with Charm

Learn to build a simple mortared stone wall for a defined, iconic look.

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Project Overview
  • Working Time: 3 days
  • Total Time: 3 days
  • Skill Level: Intermediate

Stone walls are functional, sure, but they're also the sort of architectural feature that demands a second look. With stacks of who-knows-how-old stones, these timeless takes on a fence make a statement that's both casual and stately. They exude an aura of permanence, giving even the newest landscape a sense of rootedness. But stonework also has a reputation for being expensive. With our step-by-step instructions, however, you can go the DIY route and learn how to build a rock wall with mortar over a long weekend.

Start with the wisdom of an old stoneworker's adage: "One stone over two, two stones over one." In other words, stagger the seams of your rock wall, and if you're using fieldstone, take another bit of classic advice: "Pick stones that nest." That means choosing rocks with contours that hug each other as closely as possible where they meet.

Make sure to check local regulations before you begin, confirming that your plans comply. Since mortared stone walls are typically heavier than mortarless dry-set walls, building codes often include specifications for the footings. (Mortared stone walls need a concrete footing to prevent cracking due to frost heave.) Many require the use of reinforcing rod. There may also be also regulations requiring professional engineering, depending on the height of your wall.

Allot roughly two to three days to lay a 3x10-foot wall. But take your time: Stonework is a matter of continual trial and error, testing to see which combination of stones works best. Make sure to prepare the site and order your stones in advance, then get ready to start stacking.

What You'll Need

Equipment / Tools

  • 1 Tape measure
  • 1 4-foot level
  • 1 Mason's trowel
  • 1 Mason's line
  • 1 Line level
  • 1 Concave jointer
  • 1 Gloves
  • 1 Rubber mallet
  • 1 Stiff brush
  • 1 Mortar bag

Instructions

  1. Choose Your Stones

    Pick stones that blend well with each other in both color and texture, selecting a variety of sizes. You can use uncut rubble, semidressed stone (roughly cut into rectangular shapes), or ashlar (stone that is carefully squared and trimmed). Keep in that mind that setting uncut fieldstone takes substantially more time, since it requires more trial-and-error to make the courses fit together. Have the stone delivered as close to your building site as possible.

  2. Lay Out and Pour Footing

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    To prevent the joints from cracking, a mortar wall must be built on a firm foundation. Dig a trench about 6 inches wider than your wall. It must be deeper than the frost line, which varies by area, and at least 12 inches deep for a 3-foot-high wall. Tamp gravel in the bottom of the trench, then pour at least 8 inches of concrete, topping it off 2 inches below grade. Although concrete takes a few weeks to cure fully, you can generally begin building the next day, after the concrete has dried overnight. While the footing cures, divide your stones into size groups.

  3. Dry-Set the First Course

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    Dry-set the first course, starting with bondstones (stones that are as long as the wall is wide) on the ends and then every 4 to 6 feet in between. Lay down stones that fit neatly in between the bondstones. Plan the layout so square stones are set at the corners and flat-faced ones line the edges. Use the largest ones you can find but keep the size relatively consistent.

  4. Set First Layer

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    Remove 3 to 4 feet of the stones from the first course, and set them aside in the same order. Spread a generous layer of mortar—at least 1 inch—on the footing. Replace the stones and tap them into place with a rubber mallet.

  5. Continue Setting First Course

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    Continue removing stones, spreading mortar on the footing, and resetting the stones in the first course. Fill the gap between the front and rear wythes (the exterior faces of the wall) with smaller stones and mortar. Set a 4-foot level on the stones to make sure they're close to level. Since the surface of the stones is rough, you won't get a precise reading from the level, just a general indication.

    Editor's tip: You may need a little help holding up the stones. Irregular stones are bound to leave gaps that cause the stone to tip before you can mortar it. Cut a few small wooden wedges before you start laying the wall and keep them close. As you work, insert them in the gaps to help the stone stay level. Mortar around the wedges and remove them once the mortar is set. Then fill in the holes left by the wedges.

  6. Pack Mortar

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    After you've finished the first course on a short wall, pack mortar into the joints. For any space in the core (the middle of the wall) that's more than ½- to ¾-inch wide, add a small piece of stone or rubble to fill the gap. Depending on the size of the rubble, you may have to fill the core in layers, adding mortar between layers. Smaller rubble is best for the core.

  7. Create Guide

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    Drive stakes into the ground at each end of the wall beyond the footing, and tie mason's line tightly between them. Set the line at the height of the next course and use a line level to ensure it's even. Adjust this guide with each course.

  8. Lay Second Course

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    Select stones from the size-sorted piles you created, then dry-lay the second course for both wythes. Choose stones that will sit approximately ½ inch below the staked mason's line. Remove these stones and set them aside in the same order. From this point, you can build your wall with leads—that is, build up the corners and fill in between them as you would a brick or block wall.

  9. Continue Setting Courses

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    Continue setting courses, moving the mason's line higher as you work. Always choose flat, smooth stones for the visible faces of the wall. From this course on, spread mortar one stone at a time, using enough mortar to form a bed for each stone.

    Fill in the core and mortar the stones. Then dry-fit the next row and reset it, checking the batter as you go. (This is the subtle angle in a rock wall, with the top slightly narrower than the bottom to prevent toppling.) If you've made your mortar a little wet for ease of application, don't set more than three courses a day—the weight of the stones will cause the courses to sag before the mortar sets.

    Lay bondstones every third course, at roughly 4-foot intervals. When the mortar begins to set up, stop laying stone and finish the joints. Cap the wall with a course of flat stones large enough to cover both wythes. When you mortar the capstones, do not finish the joints. Brush them flush with the surface of the capstones to keep water from collecting and freezing there—it could split the mortar or the stone.

  10. Strike Joints Smooth

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    When the mortar begins to set up, brush off the excess with a whisk broom or stiff brush. Once the mortar is firm enough to hold a thumbprint, run a concave jointer over the joints to compact and smooth the mortar. Let the mortar set up a little more and rebrush as needed.

    Editor's tip: As you strike the joints, you'll usually find some places between stones that need extra mortar in order to be even with the rest of the joint. Use a mortar bag to fill them. Mix mortar slightly wetter than you would if you were troweling it, fill the bag, and squeeze the mortar into the gaps. A bag is easier to control than a trowel and reduces the amount of mortar spilled on the wall or ground.

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