As with all our hardscape projects we feel we this can’t be said enough. The key to building and having any hope of longevity with respect to brick paving stones, and or brick retaining wall blocks is having a proper base/foundation. As you can see from the photos the finish is smashing, but without a proper base it just won’t hold up. We use at least 6 inches of compacted base gravel and then an inch of sand or crusher dust for the fine leveling.  As critical as the base is, the backfill/drainage behind the retaining wall is equally important.  The wall is only as good as the drainage system and drainage rock behind it. You don’t want to spend your hard earned money to have it fail!