Dry stone retaining walls add beauty and enhance the value of your property as well as retain slopes to add useable level ground. The design and construction of dry stone walls are projects that can be undertaken by most homeowners with great success.

When designing any wall, it always helps to position the wall in the middle of the slope. This gives an equal amount of soil removed that will be needed as backfill (See Fig. 1).

On uneven grades, the contour should be taken from the bottom of the wall while all courses are laid flat creating a wall of varying heights with a level top (See Fig. 2).

All dry stone walls should be constructed with the thickness equal to one half of the overall height. Walls should be built leaning back toward the slope about 2 inches per foot of height for stability (See Fig. 3).

For walls that exceed 2-1/2 feet in height, the use of bonding stones and a drainage system are necessary for long-term stability. Bonding stones stabilize a wall and connect it to the slope that is being retained. Drainage behind any retaining wall of size is critical. Hydraulic pressure is responsible for the failure of most walls. To incorporate a drainage system in your wall, leave a 12-inch wide space behind the wall and lay a 4-inch perforated drainage pipe at the bottom and backfill with clean aggregate. Separate the drainage system from the slope with a layer of landscape fabric, which will stop soil intrusion (See Fig. 4).

The drainpipe can be directed to a lower area away from the wall, reducing the chances of erosion.

To incorporate a drainage system in your wall, leave a 12-inch wide space behind the wall and lay a 4-inch perforated drainage pipe at the bottom and backfill with clean aggregate. Separate the drainage system from the slope with a layer of landscape fabric, which will stop soil intrusion (See Fig. 4).

The drainpipe can be directed to a lower area away from the wall, reducing the chances of erosion.

For dry stone walls 2-1/2 Feet and under, elaborate drain systems are not necessary, although landscape fabric is still necessary to stop soil on the slope from washing through the wall creating erosion above and behind the wall. Bonding stones should still be used for structural integrity.

**Tools needed**

• Shovel

• Small sledgehammer

• String

• String Level

• Stakes to hold string

• Hand tamper

• Safety glasses

• Tape measure

• Builders level

**Materials needed**

• Stone

• Landscape fabric

• For walls more than 2-1/2 Feet tall:

Add aggregate and 4” drainpipe

**Base stones:**

The broadest and thickest stones used to make the first course or the foundation of a dry stone

wall.

**Bonding stones:**

Longer stones turned to run from the front face of a wall through the wall and protrude out the back of the wall into the backfill material. These stones add structural as well as lateral strength to a wall.

**Course:** A continuous horizontal layer of stone that maintains a constant level height.

**Hydraulic pressure:** The lateral force created by water when its natural flow is slowed or stopped.

**Cap stone:** Uniform sized stones used as the top course on a wall.

**Shim stone:** A small and/or thin stone used to level and stabilize other stones in a wall.

**Stone:**

Determine the length, width and height of the wall in feet. Average the width and the height if they are not consistent. Multiply the length x width x height to get the cubic footage. There are about 15 cubic feet in one ton of stone so divide the cubic footage of your wall by 15 to determine the quantity of stone needed in tons.

**EXAMPLE:**

A 20′ long wall that is 2′ tall needs to be 1′ wide.

20′ x 1′ x 2′ = 40 cubic feet

40 divided by 15 = 2.67 tons

Landscape fabric:

Take the height of the wall and add 1.5 feet then multiply by the length of the wall to attain square footage.

EXAMPLE:

20′(2′ +1.5′) = 70 square feet.

**Drainage aggregate:**

Assuming a 12″ wide drainage system. Multiply the length of the wall by the width of the drainage aggregate

by the height of the wall to get the cubic footage. There are 27 cubic feet in one cubic yard so divide the

cubic footage by 27 to get the quantity of cubic yards of drainage aggregate needed.**EXAMPLE:**

20′ x 1′ x 2′ = 40 cubic feet

40 divided by 27 = 1.5 cubic yards**Drainpipe:**

The length of the drain system behind the wall for perforated pipe and the distance to the drain area in

solid drainpipe if draining elsewhere.**Backfill material:**

Multiply the length x width x depth of the area to be filled to attain the cubic footage. Divide the cubic

footage by 27 to get the quantity of cubic yards needed. Note: Soils will compact up to 20 percent so a little

extra may be necessary.

**Getting Started**

Dig a level bottom trench wide enough for the base stones to fit into and about the same depth, as they are

thick, then compact the bottom with a hand tamper. Set stakes outside of the wall ends so a string can be tied on and leveled with a string level above the walls maximum height. Lay landscape fabric covering one half of the base trench and extending back toward the slope.

Determine the lowest point of the trench by measuring down from the string. Pick out the base stones and begin laying at the lowest point of the trench in both directions covering the landscape fabric to hold it in place. The base course must be level and firmly installed so use shim stones to help fill in voids and level individual stones as needed. If shim and filler stones are in short supply, break up some whole stones with a sledgehammer. We are definitely not building a piano here. The correct attitude for building a dry stone wall is “If you can’t force it, break it. If you can’t break it, your hammer is most definitely too small!

If the base course fades below the intended grade too far, go back to where you started and begin the next

course. Overlap the joints that are between the stones below, and span the width of the wall with bonding

stones as often as possible. Continue this process until the base course is complete (See Fig. 5).

Each course of stone should be stepping back slightly to achieve a two-inch per foot lean back toward the

slope. This helps the wall retain the slope. Use a builders level and tape measure to check your step back.

While stacking the courses, lay the landscape fabric tight up against the back of the wall and install and

compact the backfill as you go. For larger walls add the drainage aggregate, the pipe, and the backfill as you go while keeping the aggregate separated from the backfill with the landscape fabric.

For walls more than two and one half feet tall, install bonding stones every 18″ of height about four to six

feet apart. Uniform thickness stones should be saved for the cap course. Level the wall before installing the cap course and lap the landscape fabric over the top of the wall, then trim off excess until it covers half of the top of the wall.

Install the cap course tightly to hold down and hide the landscape fabric. If the wall will be in a public area or will be used as a sitting wall, the cap course should be mortared down or glued down with a construction

adhesive suitable for masonry.

Video by Handyman Startup

This video will guide you step by step to install a flagstone patio that will have beauty and last for years. There are some material differences between where this video guide was filmed and Southwest Florida. We have limestone base and screening sand here versus granite dust, however the installation is the same.

]]>installing Thin Veneer Stone.

**First**, you will need to calculate the total square footage of the surface(s) you will be covering. Measure the width and height of each section, in feet. Multiply the width by height to get the square footage. Add the square footage of all sections together to get your total square footage. Measure any windows or door openings the same way, and subtract the square footage for those from your total square footage.

HINT: If you measure by inches, you can convert to feet by dividing the total square inches by 144 (144 sq.in. = 1 sq.ft.).

Every house is different and many will have complex shaped surfaces to calculate. Commercial buildings can be calculated in the same manner, just on a larger scale. At a minimum, you will need to be able to calculate the area of rectangles and triangles.

Area = Width x Length

Area = Length x Height / 2

both rectangles and a triangle to be covered. The triangle doesn’t have to be a perfect triangle, just be sure

to measure from the ridge point straight down to a point along the fl at line (L) that is 90 degrees to the ridge

point. (See Fig. 2). It may be helpful to use a “plumb-bob” attached at the ridge point and hanging down to

the horizontal line (base of the triangular section). Then use a framing square to fi nd the 90 degree point.

Measure the height along the plumb-bob line.

To calculate the three (3) surfaces shown in Fig. 3, you will need to measure the rectangular section (the wall the window is in) and the triangular section shown (the point above the base of the roof overhang to the roof ridge, as shown by H & L).

First, measure H & L (in feet).

Now multiply H by L and divide your result by 2. This gives you the square footage of the triangle. (You divide by 2 because a triangle is only half the area of a rectangle or square with the same width and height).

Now measure H2 and W2 (the main wall).

Then multiply H2 by W2. Add this result to your last result. Now measure the window opening width and height the same way, multiply width by height, then subtract that result from the total square footage you just calculated.

Now measure W3 & H3. Now total the results together. This will give you the total square footage to be covered.

Next, you will need to calculate for outside corner pieces, by linear footage. The example in Fig. 3 has only 2 outside corners (corner 1 & corner 2). Measure the height of each corner to get total linear footage. If you have multiple corners, measure each separately and total together.

HINT: If you measure the corner heights in inches simply divide total inches by 12 to get total feet.

Every house/building is different. So, be sure to plan ahead by noting which areas will be covered by the thin veneer stone, then measure the square footage (multiply the width by height, in feet) of each section and add the results together. Then subtract the total square footages for any windows or doors that are inside those sections. And remember corner pieces of thin veneer stone are sold by linear foot. Each linear foot of corner pieces average approximately .5 square feet, depending on the type selected.

You could run into other shapes you will need to calculate for, such as half circles, arches, hexagons, etc. You should refer to basic geometry formulas for information about how to calculate those. It is important that you use the same measurement system (i.e. inches or feet), to avoid confusion. For example, if you measure a line that is 7 Ft. 3 In., multiply 7 x 12 and add 3 to get 87 inches. Divide by 12 to get 7.25 Feet. Calculating your total square footage and linear feet (for corners) is important so that you do not purchase too little or too much stone to do the job. We do recommend that you add about 10% to the total to allow for waste from cutting/trimming pieces to fit. Many masonry contractors can assist you in this process.

Cover the wall surface with a weather-resistive barrier. The barrier shall be equal to that provided for in the U.B.C. Standard No. 14-1 for kraft waterproof building paper of asphalt-saturated rag felt. The building paper or felt shall be applied horizontally with the upper layer lapped over the lower layer not less than 2 inches. Where ertical joints occur, the felt or paper shall be lapped not less than 6 inches.

**Note:** Do not attempt to apply “thin stone” directly to a surface such as sheetrock.

Any surface that you apply “thin stone” to must be capable of supporting the weight of your product and of the masonry materials used. Sheetrock, wallboard and other similar materials, while being structurally sound building products, are too flexible for direct installation. You will need to cover these weaker surfaces with plywood or other approved sturdy backing materials.

Next, install 2.5 lb. (or heavier) diamond mesh expanded metal lath.

**Note:** Lath is directional. It has a top and bottom side. Use galvanized lath for exterior applications. Black metal lath (non-galvanized) may be used for interior applications.

Overlap lath sides by not less than a ½” and lath ends by not less than 1”. Attach the lath using galvanized nails or staples every 6” on center vertically, and every 16” on center horizontally, penetrating the studs a minimum of 1”. Again, be sure to attach the metal lath with the small cups pointing upwards. Double wrap metal lath a minimum of 16” around all inside and outside corners. Then apply a ½” thick scratch coat of mortar over the metal lath, rake gently, then allow it to set. Mortar can either be type N or S or a premixed mortar designed specifically for thin stone veneer.

**Installation over most clean unpainted, unsealed, untreated brick, block, concrete or other masonry ****surfaces:**

Surface preparation may not be necessary over cast-in-place concrete that has cured. This surface can be roughed or lath can be applied. Keep in mind that applying an uncured masonry adhesive to a cured surface can pose problems. It may be necessary to rough the surface (sandblast, scuff, etc.) or apply lath. Applying lath is highly recommended for maximum structural integrity.

**Installation over painted, sealed or treated brick, block, concrete or other masonry Surfaces:**

The surface must either (a) be cleaned back to the original surface by sandblasting, water blasting, acid etching or wire brushing, or (b) have metal lath a ached using corrosion-resistant concrete nails with a scratch coat applied over the metal lath.

Using a mason’s trowel, apply approx. ½” thick even layer of mortar to the entire backside of the stone. Then press the stone firmly into place on the prepared wall surface, squeezing the mortar out around all edges. Using a gentle wiggling action or tapping of stone will ensure a good bond. For jointless/dry-stacked

installations, it’s important when setting the stone that the edges of the stone are properly sealed with mortar to ensure a satisfactory bond.

If the stone is being installed onto a very dry surface or in a hot/dry climate, the wall surface should be wet to prevent excessive absorption of moisture from the mortar. This can be done by spraying or brushing water onto the wall surface. The wall surface should be allowed to dry for a few minutes after wetting to

eliminate excess surface water.

After the stone has been applied to the wall surface, use a grout bag to fill the joints with mortar, forcing grout into any voids. Any mortar that accidentally gets on the stone should be allowed to set until dry and crumbly, and then brushed off with a dry whisk broom.

We recommend grouting to fill noticeable voids and to conceal cut or broken stone edges. Use approx. ½ the amount of grout as for the “jointed look”. The “dry stack” appearance will result from deep striking of the joints. When dry stacking thin veneer stone consider using thinset. This product will maximize the mechanical bond.

When the mortar joints become firm (normally 30-60 minutes), use a wooden or metal striking tool to rake out the excess mortar to the desired depth while at the same time forcing the mortar into the joints so as to thoroughly seal the stone edges. Be careful not to work the joints too soon or the mortar will smear.

After working the joints, use a whisk broom to smooth the joints and clean away any loose mortar from the joints and stone face. Loose mortar and mortar spots which have set for only a few hours clean up easily and should never be allowed to set up overnight.

At this point, it is necessary to recognize the fact that a 3/8” masonry joint represents up to 18% of what the eye sees after completion. If you appreciate the stone selection and want to focus on the natural beauty of “all-natural thin stone” we recommend narrow grout joints that are raked or recessed back. This will allow the stone to stand out with its natural beauty.

**Note**: It is important to divert water run-off away from stone surfaces by using gutters and fl ashing. Water run-off combined with severe freeze/thaw conditions can result in damage. Stone should not be used below water level. Do not install while temperatures are below 40° Fahrenheit. Provide supplemental heat if necessary to ensure a minimum temperature of 40° Fahrenheit between installation and mortar drying for approx. 24 hours.

Several companies now produce premixed “Veneer Stone Mortar” and should be used, if available. Many stores offer the Quikcrete Polymer Modified Veneer Stone Mortar which is premixed and only requires you to add water. It comes in 80 LB bags and covers approx. 17 Sq.Ft. as a scratch coat, and slightly less for bond coat.

Be sure to follow the instruction for the mortar you purchase. If you are installing veneer stone with a “dry-stack” look, you should use a polymer-modified veneer stone mortar for a better bond. You can also add a bonding agent to type S mortar. If you’re installing with a fully grouted joint look, the standard veneer stone mortar should suffice.

**If you Mix type N mortar –**

2 parts type N masonry cement

3 to 5 parts masonry sand and water

**– OR –**

1 part Portland cement

1 part Lime

3 to 5 parts masonry sand and water

If you Mix type S mortar –

3 parts type S masonry cement

5 to 7 parts masonry sand and water

**– OR –**

2 parts Portland cement

1 part Lime

5 to 7 parts masonry sand and water