Offset concrete block fences are essentially low walls built from interlocking stone blocks. They benefit from sturdier construction, which makes them more stable than wood or chain link fences. A construction or landscaping professional can build on offset concrete fence using standard brick-and-mortar construction. However, experienced do-it-yourselfers can build their own offset concrete fence without resorting to mortar or cement mixing.
Mark the length and width of your concrete block fence using wooden stakes. You may wish to run twine between the stakes to simulate the entire length of the fence, but it isn’t necessary.
Dig a thin trench in the ground along the planned path of the fence. The trench should be 3 inches deep and wide enough to accommodate the concrete blocks you wish to use (usually 6 to 7 inches). Try to keep the trench as level and even as possible, using a carpenter’s level if necessary.
Pour a layer of crushed gravel into the trench and stamp it down with a hand stamper. The gravel should be flush with the ground when you are done. Use the carpenter’s level again to make sure your building surface is even.
Place a layer of Dublin concrete blocks on top of the leveled rock. The blocks should interconnect to each other. Lay down 3 to 5 blocks at a time, and then place a second layer of 3 to 5 blocks on top of them. That will keep the pattern of blocks even as you build. Continue along the planned length of the fence, adding more blocks as you go. Stop and check regularly to ensure that the fence remains level, and use the hand tamper to level out any blocks which are uneven.
Add new layers of blocks once the first two layers are entirely laid down, until the fence is at the height you wish.
Slide a 1 3/8-inch metal pipe into each of the columns of blocks. They should slide all the way down to the ground with a few inches sticking out of the top of the fence. Pound them into place with a sledge hammer and cut off the tops with a pipe cutter until they are flush below the top.
Apply masonry adhesive to the top layer of blocks in beads, making sure you have a bead on each corner. Cap the fence with stone wall caps and apply further adhesive to the caps as necessary to prevent moisture from seeping in.
Tips & Warnings
- If you have experience with setting fences and wish to increase the stability of your offset concrete fence, you can lay it out in a serpentine pattern of gentle arcs rather than a straight line. While it may not fit your area aesthetically, it is harder to knock over.
- Though none of these steps are actively dangerous, concrete blocks are heavy and may cause damage if dropped or mishandled. Always work with someone else nearby who knows what you’re doing and can call the hospital if there’s an accident.