Precision-ground concrete blocks make it easy to build a wall.
Synopsis: An architect makes the case for dry-stack block walls. They are made from precisely manufactured concrete blocks that are stacked into walls without the need of mortar joints and then filled with grout. Material costs are higher, but labor costs are much lower than typical block construction.
Designers have been trying for years to develop a mortarless concrete-block system that could be used by unskilled builders. The concrete blocks in use today look quite uniform, but their dimensions actually vary so much that mortar is necessary not just to hold them together, but also to make up for their irregular sizes. Mixing and applying the mortar to the joints in a block wall require skill and time, and the process accounts for 20% to 30% of the material and labor in a masonry project. Manufacturers have recently developed mortarless, interlocking block for industrial and commercial buildings. I use it in house construction. It’s called drystack block, and it can be laid up as easily as the plastic toy blocks in a Lego set.
Dry-stack blocks look very much like ordinary concrete blocks, but they are consistently a full 16 in. long and 8 in. high (regular blocks are an inexact 3/8 in. less in each direction to allow for the mortar joint). During the manufacturing process, the dry-stack blocks I use are sent through a machine that grinds the top and bottom surfaces to a tolerance of 0.005 in. These parallel, exact and smoothly ground surfaces are what allow the block to be laid up so regularly without mortar.
Most dry-stack blocks have interlocking tongues and grooves at their ends to help align and secure them during placement. Besides standard blocks, there are also bond blocks for bond beams (these have knockouts to accept horizontal rebar), and half blocks. Special corner blocks are manufactured…