Dry Set Flagstone Patio

A dry set stone patio can be a simple project to add additional living space to your outdoors. This project can be completed in a relatively short amount of time and does not require special tools or expertise. All you need is a little elbow grease and a good imagination.

Download a PDF of our Dry Set Patio Project Guide

Select a guide section:

Required Tools

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Materials Needed

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Coverage Calculations

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Preparation

  1. Please remember to call before you dig! Having to repair broken utilities will cost you more time and money then expected. In Georgia, call 1-800-282-7411 or visit www.gaupc.com
  2. Mark the proposed area to get proper measurements and a visual reference of where your patio will be installed.
  3. Measure the area. Reminder: When purchasing material account for at least 10% waste due to the shaping and cutting of the stone.
  4. Keep in mind that patios need to drain rainwater. Slope the patio in one direction at least .25” for every 1’ of patio. This will keep water away from the house and keep water from pooling on the patio.
  5. The thickness of the flagstone, what type of soil is present, what the patio is used for, and how well the surrounding landscape drains are all factors that will determine how much base material is required.
    • Lower traffic and thick flagstone (2.5” and thicker) should be fine with ~2” of Granite Sand.
    • Medium traffic and standard thickness flagstone (1.5” to 2”) should use at least 2” of Crushed Stone Base and ~1” of Granite Sand.
    • Heavy traffic and standard thickness flagstone (1.5” to 2”) should use at least 4” of Crushed Stone Base and ~1” of Granite Sand.
    • We do not recommend using thin flagstone for dry set patios.

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Installation

  1. Remove the soil where your patio will be built. Ex. 2″ Flagstone + 2″ Crushed Stone Base + 1″ Granite Sand = 5″ of soil excavated to bring the top of the flagstone flush with the ground level.
  2. (optional) Once the soil is removed, place landscape fabric over the excavated area. This will help keep the soil underneath from mixing with the base material and provide additional support. This step is highly recommended for areas that don’t drain, as well as high-traffic areas.
  3. (optional) Set the landscape edging around the perimeter of the patio area. This will ensure that the base material does not spread out under compaction and stays contained where it belongs.
  4. Spread and compact the base material. If you are using Crushed Stone Base, it should always be the bottom layer and Granite Sand should always be closest to the flagstone. Using a tamping device, compact the base no more than 2” deep at a time. Ex. If you have 4” of base material, lay down 2” then compact, then spread another 2” and compact again. This may seem like a lot of work but it is absolutely necessary to ensure proper compaction. Wetting the base with water will also help compaction. For larger patios consider renting a plate compactor from your local tool rental store. These compactors will drastically cut the time and energy required for this step.
  5. Granite Sand is used as the final layer for the base. This sand does not have the large pieces of gravel that Crushed Stone Base has, but it does have fine particles that make it easy to level the flagstone pieces. The key to using this material to your advantage is to make it smooth and level. A great way to accomplish this is to lay two pieces of 1”OD pipe on the Crushed Stone Base, parallel to each other. Spread the sand on the ground so that the pieces of pipe are just slightly buried. Use a piece of 2”x4” to span the pieces of pipe and drag the board towards you. As you drag the board, the pieces of pipe keep you from moving any material under 1” thick and smoothing the base at the same time. Remove the excess sand or add more to fill in low spots. Pull up the pipe and repeat on the next section.
  6. Let the jigsaw puzzle begin! Placing the stone can be the most challenging part of this project. These instructions and tips will help guide you:
    • Lay the stone out around the area, not in it yet. It’s always a good idea to be able to visualize the material you are working with so you can spot that perfect piece.
    • When placing the stone, press it firmly into place while wiggling it side to side and slightly rotating. Air pockets under the stone are your enemy in this case. Air pockets and voids mean there is no support under the stone and can lead to cracked stones in the future.
    • Start around the edges of the patio. Search for pieces that already have straight edges and place them on the straight sides of the patio. This will reduce the number of straight cuts you have to make during your project.
    • Watch your joints. As you place the flagstone in the patio, keep your joint width to a minimum. Recommended joint size is 1.5″ or less. The larger the joint, the more it is prone to washout. You can chip or cut the edges of the stones to reduce joint size.
    • Make sure you break up the joints through the overall patio. Long consecutive joints will create a highway for runoff water, washing  joint sand away.
    • Don’t spend too much time on one piece. The rule of thumb is: “If you have to turn or flip the stone more than 3-4 times and it still does not fit, toss it to the side and try another.” It will fit somewhere else.
    • Constantly check the level of the stones with the torpedo level, and how level they are to each other with the 2′ or 4′ level. If a stone is out of level you can always add or remove Granite Sand from underneath it. A rubber or rawhide mallet will help you tap it into alignment. Rawhide is great because it does not leave marks on the stone, while some rubber ones will.
    • Reshaping some pieces of stone will be required. Use the rock hammer or stone saw to shape them to the desired contour.
  7. Next, fill all the joints with granite sand. This can be accomplished by tossing a few shovels of Granite Sand on top of the joints and using a push broom to move the sand into the voids between the stones. If you want to make sure the joints are packed well, you can use the handle end of your shovel as a tamp. Most people just soak the Granite Sand with water, which will produce the same results. Note:
    • Stone Forest does not recommend mortaring any joints on a dry set flagstone patio. It may give your patio a finished look at first, but over time the mortar usually cracks and becomes hard, sharp edges. This is caused by the base under the patio being made of “flexible” material and settling of the ground over time. If you are interested in mortared joints, please see our guide on Mortared Flagstone Patios.
    • Stone Forest also offers Polymeric Sand. This is specially designed joint sand for pavers and flagstone patios that have joint widths within certain tolerances. It contains polymers that allow the patio to retain the joint sand much longer than traditional Granite Sand, yet it allows the patio to stay “flexible.”

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Project Options

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Maintenance

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The Fine Print

Please be aware that each project is unique and may pose different obstacles and circumstances that this guide cannot foresee. It is intended as a reference only. Most of these installation techniques are great for our geographic location here in Atlanta, GA. Soil conditions and climate play a large role in how each project is constructed. For example, if you live in the Northeast you will have to use a deeper base material to account for the freeze/thaw cycle that is notorious for upheaving patios. Stone Forest cannot be held liable for any damages incurred by the use of this guide.

Please seek a professional contractor’s advice if you are uncomfortable with undertaking a project you have not completed before.

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