There are three basic ways to install a stone patio or walkway: Ground Set, Dry Lay (commonly referred to as Sand Set), or mortar set.
The simplest and most economical way to install step stones is directly in the ground, or Ground Set. This method is pretty self-explanatory and certainly non-technical. The most important thing to consider is the soil’s ability to drain. Areas of poor drainage will cause the stones to settle over time.
The most common application is Dry Lay and the concept behind it is simple. The stones are set in a larger gravel “footing” so that each individual stone will stay put and not settle. Sometimes this method is also referred to as Sand Set however we recommend crushed gravel with fines (such as ¾” minus or ¼” minus) instead of sand.
The third method is Mortar Set, which sets the stones in mortar on top of an existing concrete slab. This type of installation has mortared joints which gives it a more formal appearance as well as makes it easier to clean.
Ground Set – Use 2 inch or thicker flagstone or step stones
If they are being installed in your lawn, simply cut out a space large enough for the stones to fit. You may want to use a small amount of sand or fine gravel to assist in making the stones level. Be sure the ground you’re setting them in is well-drained, or they will settle unevenly over time. Smaller step stones may settle more than larger ones simply because they have a smaller footprint. If settling does occur simply add more soil or gravel under each stone to bring it back up to level. To avoid having to bring them back up to level in the future we recommend either a dry lay in 1/4-inch minus crushed gravel, or mortar set.
Dry Lay – Use 1-2 inch or thicker flagstone or step stones
1. Check with local building codes and appropriate utility companies before digging.
2. Excavate the desired area to a depth of your thickest stone plus 2-3 inches for the gravel base. For example, if your stone is 2 inches at the thickest point, then you’ll need to allow for a 4-5 inch total depth. You can achieve this one of two ways, or a combination of both: 1) by digging down into the existing grade, or 2) building on top of the existing grade and adding forms or a border along the sides to contain the area.
3. Add the 3 inches or so of 1/4-inch minus crushed gravel and pack it down as much as possible. You might consider using a hand-tamper or renting a plate compactor for larger areas. After tamping use a fine spray and water it down. This will help compact the base properly, which is called hydro-compaction.
4. Arrange the stones in the desired pattern trying to keep consistent joints, most common are about 1”, and breaking up the joints so there are no continuous running lines. Stones may be hand-trimmed with a rock hammer or saw cut to achieve desired fit.
5. Using a rubber hammer, tap the stones into place adding 1/4-inch minus to low areas and removing from high areas so the stone seats firmly. Check with a carpenter’s level to ensure entire area is level, allowing for a slight pitch towards the edges for drainage.
6. Sweep remaining 1/4-inch minus over the top to fill the joints and follow up with a light spray again. Repeat spray a couple weeks later. Another option for the joints is a polymeric stone dust called Gator Dust. This will give you a more solid joint, similar to a mortared joint but designed for patios with a gravel base. However if you prefer mosses or other vegetation to grow in the joints adding topsoil to the joints instead of 1/4-inch minus would work well.
Mortar Set – Any thickness, however 1 inch thick or less is easiest to work with and to cut
1. Before laying any mortar, first arrange the stones over an existing 3-4 inch thick concrete slab in the desired pattern trying to keep consistent joints, most common are about 1/2 inch wide, and breaking up the joints so there are no continuous running lines. Stones may be hand-trimmed with a rock hammer or saw cut to achieve desired fit.
2. In one tub mix concrete using 1 part cement and 4 parts sand to create a firm mixture that you can ball up easily in your hand. You may also opt for a premix that you just add water to. In another tub, mix up some “concrete butter” which is a much softer mixture of plain cement, like that of soft butter, but not runny.
3. Remove a few of the stones, and lightly dampen the area of the concrete slab you’ll be working on.
4. With a trowel lay a 1-inch or so thick layer of concrete and set the stones in it, lightly tapping them into place. The trowel handle works great for tapping. Check to ensure they are level and allow for a slight pitch for drainage.
5. Now carefully remove those stones and apply a small amount of “butter” on the
concrete so as to not disturb the print of the fitted stones. It doesn’t take much “butter.”
6. Return each stone and gently tap them into place, again leveling as you go.
7. Remove the excess concrete from the joints while it is still soft to a depth of that of the stone.
8. Clean the rock surface with a sponge and water and allow it to set 36 hours.
9. Make sure joints are clean, then mix grout using 1 part cement and 1 part mason sand and prepare until stiff.
10. Fill the joints with the grout and pack it in as tight as possible, trying to keep as much off the stone surface as you can.
11. Strike the joints with a tool to allow for consistent, smooth joints.
12. Clean stone surface again and allow grout to set 36 hours, keeping it moist throughout the curing stage.
13. Consider consulting a stone mason for more detailed instructions or suggestions.