With radius dimensions in mind, find the center point of the radius and mark with paint, chalk or flour. The easiest way to mark the dimensions for the pit, benches and the garden area is to work outward from the center point of the firepit using a stake and a string marked with measurements for each of the concentric circles required. Remove sod, if necessary, and apply a preemergent herbicide to keep grass from growing back. Mark concentric circle areas for pit, benches and garden with paint, chalk or flour. Soil can be removed in advance to save time.
Because the firepit bricks are 6" high, dig the pit area down 6" so the base row of bricks will be at surface level. Install the first row of bricks according to manufacturer's instructions. This row has to be level from front to back and side to side since it determines the stability of the entire pit. Install the second row of bricks, staggering them so the vertical joints are offset.
When the firepit walls are in place, backfill with dirt around the outside base of the blocks to give the walls support. Tamp soil into place (Image 1). Add several inches of desiccated gravel to the floor of the fire pit (Image 2). This provides a nonflammable surface for the wood to sit on, and since it is porous, it will allow water to filter through and not sit on the surface. Tamp in place for a smooth surface.
Top caps are next added to the fire pit walls. They are the same material as the walls, but they have a different texture and color to add interest to the design. Lay them out and blend the color patterns before securing in place. Use mortar or construction adhesive to attach the top caps to the firewalls. Make sure the top of the walls are clean and dry before applying adhesive. Premixed mortar is used here. Make sure the caps are level until dry. Use shims, if needed, to hold caps in place until dry. Since the caps sit close together, side mortar is not needed.