Patio blocks, also called landscape blocks, include a family of cast-concrete masonry units used for paving patios and walkways and for building retaining walls, garden walls, columns, planters and other outdoor creations. You can build an attractive durable bench with landscape blocks made for standard walls and columns (as opposed to retaining walls) and any rot-resistant lumber or timbers of your choice. One popular bench design features two freestanding block columns bridged by wood planks or timbers to form the seating area.
Prepare a stable base for each column. Typically, a good base includes a 4-inch layer of crushed stone, tamped so it is smooth, flat and perfectly level.
Lay the first course of block for one column onto its base. Butt the edges of the blocks together to form a square. Use a 2-foot level to make sure the blocks are level across the top.
Measure over from the first column and set the first course of blocks for the second column, using the same techniques. The distance between columns establishes the length of the bench’s seating area. Use a long, straight board set across one side of both columns to make sure the columns are properly aligned.
Set the second course of block on one of the columns, offsetting the joints between blocks in the first course in a 1-over-2 pattern (as applicable). Check with the level to make sure the blocks are level across the top and the column is plumb (perfectly vertical).
Continue setting courses in alternating patterns up to the desired level for the bench plank. Repeat to bring the second column up to the bench level. Cut a plank or timbers to overlap a portion of each column equal to one block width, or half a block length, as appropriate, using a circular saw, reciprocating saw or handsaw.
Position the plank or timbers on top of the columns and anchor it with exterior-grade construction adhesive or a suitable concrete adhesive.
Complete the course of each column, using whole or cut blocks, as needed; cut blocks as directed by the manufacturer. Add two or more courses of block, as desired, to complete the main part of each column. If recommended by the manufacturer, glue the top one or two courses in place with concrete adhesive.
Finish the top of each column with broad paving blocks or cut squares of flagstone, if desired. Glue the top pieces in place with adhesive.