In this yard, there were two different bases below the cobbles. Part of it was existing concrete, and the other part had formerly been pavers. On the concrete, the only prep work that needed to be done was a simple pressure wash. For the area beyond the concrete that formed an extension, base rock was brought in to form a solid foundation (Image 1). The base rock was laid down so that it actually rose about an inch above the existing concrete, and then a gas-powered compactor brought it down so it was just slightly higher than the concrete (Image 2).
If you are starting in a bare soil area, dig down to give yourself a couple inches of base and allow for half the height of the pavers to determine your final patio height.
Pour sand over the whole area and use a rake to spread it out about an inch thick. This will form a cushion for the cobblestones.
The different colors and styles of pavers include straight, round and fanned-out designs. For the straight type, start at one end and lay them on top of the sand in straight rows, working your way to the other end of the space. Using wire snips, remove the two smaller cobbles at the end of each mat of pavers so the mats fit together. At the end of the row, leave the smaller pavers on the mat to serve as a straight edge.
Do not use a compactor over pavers that have been laid on top of concrete. If you have laid them on top of base rock though, lightly spray the cobbles with water and go over them with a compactor. This will push them down into the base rock but not all the way.
For this project, we used a special type of epoxy that, when mixed with sand, creates a grout that hardens once it dries.
Use a portable cement mixer to mix the grout. Pour in one bag of sand, the color of which will be the final color of the grout. Then add one container each of the two-part epoxy. Finally, fill each of the containers with water and add that to the mixer as well. Pouring the water into the containers allows you to measure correctly and also to use any remaining epoxy.
Let the grout mix for about three minutes, until the consistency resembles pancake batter.
Wet down a wheelbarrow (so the grout won't stick to it) and pour in the grout. Use a foam squeegee with a broom handle to spread the grout, filling in all of the gaps in the cobbletone. It hardens in about 10 minutes.
Once you have most of the grout spread into the gaps, go over the same area with another squeegee to clean the remaining grout from the top of the pavers. Once you've finished the whole area, use a stiff-bristle push broom to clean up any remnants again. Let the new cobblestone patio dry for five hours before walking on it.