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Boral Cultured Stone® – Installing with 1/2” Mortar Joints

For this demonstration, we’ll be using Dressed Field Stone primarily, with variations shown as they apply to other products. The general technique shown here will apply to any installation with a 1/2” (12.7 mm) mortar joint.

If your project has outside corners, always begin the install with those. Notice that each corner piece has a long leg and a short leg. These should alternate as you go up the corner.

Apply mortar using any of the methods described in the Mortar Techniques section. Press each piece into the mortar bed firmly enough to squeeze some mortar out around the edges of the piece. This will ensure a good bond. As you place each piece, be sure the mortar joint remains consistent.

Special Note: When using a ledge style product — like this Country Ledgestone — you’ll also need to check your work regularly, to make sure each stone is level and plumb.

The stones should be applied around any openings, before reaching it with the courses you are laying on the rest of the wall. If you are using standard flat stones — instead of trim stones — take care to pre-select pieces that fit properly around the opening. Lay in a course of stones, at the top of the opening, that extends out at least 4” (10.16 cm) on either side. Then surround the opening with stone, working outwards, toward the rest of the wall.

Once the corners and trims are in place, you can continue by laying the flat pieces. Windows, doors and other openings, can also be finished with specially designed trim stones. Here, coordinating Monticello® Trim, keystones and sill pieces are used for a more sophisticated looking design.

For windows, the sill is installed first. Bracket locations are determined by measuring from the bottom of the window, down to the pre-cut groove of the back of the sill piece. Actual measurements will vary by installation. The brackets are installed into blocking, at locations that allow for 2 brackets per sill. To install, simply apply a setting bed of mortar to the back of the sill. Align the precut groove with the brackets and slide the sill into place. Then check for level. The brackets are designed to allow for minor adjustments in leveling and positioning during installation.

For a door or a window, after the sill is in place, proceed by installing trimstones along the sides of the opening. Next, centre a keystone at the top of the installation. Then install the remaining trimstones, working from each side, toward the keystone. Lay out the window and door trim pieces, and cut as needed, to achieve evenly spaced mortar joints. The last stone is cut to fit the contour of the keystone.

The largest part of most Cultured Stone® projects is installing the flat stones on the wall. In general, you’ll want to lay the bottom stones first; then fill in toward the top.

Special Note: Ledge style stones should be installed from the bottom up, checking occasionally to make sure each stone is level and plumb.

Keep your mortar joints as consistent as possible, approximately a 1/2” wide, depending on the type of stone you’re installing. The mortar itself need not be smooth between the stones just yet. We’ll be getting to that shortly. As you work, use small pieces to fill in voids.

Special Note: If using a Ledgestone product, choose pieces to ensure that vertical joints do not line up.

You may have to cut or trim pieces to achieve a proper fit. Consider feathering the cut edges with a hatchet of nippers. When using a wet saw, be sure the clean the stone with clean water after cutting. For best finished appearance, coat cut or broken edges with mortar. If possible, position cut edges up when they are above eye level; down when below eye level.

Remember to work at your own pace. And be sure to stand back from time to time to evaluate your installation.

Special Note: Cobblefield® is a unique teture. It is also generally installed with a 1/2” (12.7 mm) mortar joint. When using Cobblefield® stones, note that a percentage of the pieces are slightly thicker than others. These accent stones should be placed randomly throughout the wall, to add texture and shadow to the finished installation. While Cobblefield® stones are typically laid horizontally, a medium piece might occasionally be placed on end, if needed.

As you work, stop several stones short of any inside corners. Select and install the pieces that butt up against the walls on each side. They should be placed so that they knit together in an alternating pattern, as shown. Continue this process as you work the stone up the corner. Then fill in the remaining wall area as before. As you complete a section or job, fill the joints using your grout bag. Start by troweling some mortar into the open end of the bag, folding the end to form a seal. Then, squezing the bag, lay in a bead of mortar appropriate to the size of the gap.

The mortar used for the final step will need a little more water than the mortar you used for the setting bed. After the mortar in the joint has become firm to the touch — thumbprint hard — the joints are ready to be finished. Using a pointed wooden stick or metal grouting tool, impress and rake out the excess mortar, for a clean, beautiful look. Consistency is the key here. So keep checking back on your previous work as a reference; both for finishing the joints, and helping keep the joint width consistent.

At the end of the work day, or when mortar is sufficiently set up, the finished job should be broomed or brushed to remove loose mortar, and to clean the face of the stone. Never use a wet brush to treat the mortar joints. This will cause staining, that will be difficult, if not impossible, to remove. Power washing equipment should never be used on Cultured Stone® products.


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