Dry-set Patio Construction
A recent project we put together was a “dry-set” irregular patio. Let’s talk about how to make a firm and long-lasting construction.
First we determine the parameters of our design and the grade to which we’d be working. We will need to excavate soil a minimum of 6” to accommodate for 4” of mixed aggregate, some stone dust (setting material) and up to 2” thick flagstones. Some areas may be deeper than 6”, according to the grade, in order to cut out below the root line of grass and weeds.
From here we spread our aggregate (in this case 21A.) We sprinkle it with water as we spread to help it bond together. We then screed this layer and make is as smooth and uniform as possible and sloped just enough to give us a good base to work with. Then we go over the whole area with a mechanical plate tamper: Let it set.
Looks good now; ready to spread stone dust and set the stone; individually and painstakingly trying to fit just the right pieces together to make an esthetically pleasing pattern with as small gaps between stones as possible.
Keep in mind that we have grade stakes with string lines going across the area to keep us at the right level throughout this whole process.
We cut the perimeter and around the fire pit with a stone saw for a nice clean finish.
If done right and patiently, a project like this will stay intact for decades and longer.
You’ll probably have to spray for weeds occasionally between cracks or use a “sterilant” like nutra-sol for spot treatments. Another good idea is to use plant material appropriate to the light conditions such as scotch moss, creeping thyme, isotoma fluviatilis ‘Blue Star Creeper’ or the like.