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How to Build Stone Pillars

Flagstone veneer can convert ordinary columns into beautiful pillars.

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Step 1: Order the Material

Measure the plywood bases and order the stones -- allowing from two to three weeks for delivery. The veneer stone used in this project cost approximately $1,000 and regular fieldstone would have cost $1,200 plus shipping. Five-inch Indiana limestone was also ordered to use as capstone to finish off the column bases.

measure plywood bases and order stones

Step 2: Cover the Base

Cover the base with two-ply tar paper secured with a hammer stapler and be sure to start from the bottom and work your way up the column. Pull the corners tight and trim the excess with a utility knife. Be sure to wrap tar paper over the horizontal surfaces to prevent moisture from seeping in.

Note: The veneer stone can't be attached directly to the plywood because it expands and contracts with changes in temperature, thus the use of the two-ply tar paper, which will act as a water-vapor barrier.

cover base with two ply tar paper

Step 3: Attach the Metal Lathe

Cover the column with expanded metal lathe so the stones will have something to adhere to. Place the side with ridges toward the tar paper (Image 1). The front should be smooth. Nail the metal lathe through the plywood into the studs. Nail between the mesh so it's tight. Overlap the mesh about 4" on the horizontal seam (Image 2). Overlap the lathe to the next stud, which will prevent mortar from cracking. Cut and fold the metal lathe at the top of the column and nail down.

Step 4: Apply the Mortar

Use pre-mixed mortar to apply the scratch coat. When mixing mortar, always start with less water than you need because you can always add more.
When the mortar is the consistency of frosting, use a rectangular finishing trowel and a London style mason's trowel to apply generously and thoroughly over the lathe. Start on the inside and pull in from the corners. After applying the scratch coat, rough the surface up with a whiskbroom. This will allow a better bond for the stone. Allow at least two hours for the scratch coat to dry. Utilize this time to lay out the stones. Be sure to vary the size and style of the pieces for a more natural look.

use pre mixed mortar to apply scratch coat

Step 5: Apply the Stones at the Bottom

Once the scratch coat has dried, start applying the stones at the bottom of the column. Place 1 x below the area because you want to leave a little room for expansion.

start applying stones at bottom of column

Step 6: Place the Corner Stones

Start with a corner piece. Backbutter the stone with a thin coat of mortar and then put a lip around the edge creating a cup. Set it in place, wiggle it around and hold it for about 5 to 10 seconds to make sure you have good adhesion. Prepare the stone for the opposite corner in the same way.

Tip: When placing corner stones make sure you have flat surface for a good base of support.

place the corner tones

Step 7: Fit the Center Stones

Fit in the center stones between the corners. Make sure each stone is completely covered with mortar.

Note: Before putting mortar on the mud/mortar board, sprinkle some water on the board. This will prevent the board from sucking moisture out of the mortar.

Step 8: Grout the Seams

Grout the seams as you go to add extra support to the stones.

grout seams to add extra support to stones

Step 9: Chip the Stones if Necessary

If you need to make a stone smaller to fit in a space, first mark the stone with a pencil and then use a mason's hammer to chip the stone. Always chip on the flat side.

chip the stones if necessary

Step 10: Trim the Corner Pieces

Use a cut-off saw to trim the tops of the corner pieces. You'll want a level surface for the capstone.

Tip: When working with corner veneer stone pieces you don't want to hammer-cut the pieces because typically they will split right down the middle. Be sure to use a saw for these particular cuts.

Note: If mortar gets dry while you work, add a little water, and if the stone is too heavy, use a small rock as a shim to hold the stone in place.

trim tops of corner pieces

Step 11: Scrape Down the Excess Mortar

When mortar between the joints crumbles off, tool it with a tuck pointer. Let the mortar set for about 40 minutes. Scrape down the excess mortar in the joint to expose the edges of the stone. Make sure that the depth of the joint flows smoothly.

Tip: Be sure to take extra time with the tooling and striking process on the mortar. This striking is what gives the project that special "professional" look.

scrape down excess mortar in joint

Step 12: Measure and Cut the Stones

Mark 45-degree angles on the stone and measure down 21-1/2" (the length of the base for these particular columns). Use a cut-off saw to cut the stone.

measure and cut the stones

Step 13: Apply a Large Amount of Mortar

Put a generous bed of mortar on the top of the column base.

Note: You'll definitely need some help at this point because it takes more than one set of hands to apply the capstones.

Step 14: Create a Slight Cant

Allow a slight cant, about 3/8" so that water will run-off of it. Also make sure it's level. Leave a 3/8" gap between the corners of each side and fill that with grout when finished.

allow slight cant for water run off

Step 15: Fill the Capstone Joints With Grout

Leave a 3/8" gap between the corners of each side and fill that with grout when finished. When grouting, start filling the capstone joints from the bottom and work your way to the top.

Step 16: Fill the Voids

Fill in the voids between the limestone and the column so water will not collect in there. Tool the joints for a nice finished look and a stronger bond.

fill in voids between limestone and column

Step 17: Create a Rough Edge

If you prefer a rough edge on the stone, mark the top and bottom of the stone about 5/8" from edge, use a metal chisel and strike the edge of the stone at a slight angle. This is a technique called "rock facing."

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