More in Outdoors
A layer of stone helps drainage and also provides a firm foundation for the blocks. After adding wheelbarrows full of stone to the trench, use a hand tamper (Image 1) to pack it down; you can also rent a plate compactor (Image 2), which does the same job in a fraction of the time.
The base course, the first row of stones, must be level or the entire wall will lean. Because the stones in the base course must be level not only front to back but also next to one another, a level is indispensable at this stage of the project. Use a small sledgehammer to make any minor adjustments necessary in order to get all the stones leveled.
The interlocking feature for the wall system makes it possible to add the second and third courses of stone pretty quickly; as the stones are put in place, lock each one in with bars that run through holes in that stone into the one underneath (this pin system is clearly outlined in the directions that come with the wall system).
Once the wall is a few rows high, backfill it with larger stones. Add the capstones with a generous bead of adhesive to help hold each in place. (Adhesive is used only on the capstones. The other stones are held together by the pin system.)