A tower foundation (10) has a base slab (11), pillar slabs (12), and a crown stab (13), all of which are made of precast concrete structures. The slabs are all retained in position by steel guide rods (15) that extend upwardly from the base slab. The guide rods have externally threaded ends (16) configured to receive internally threaded mounting nuts (17). The crown slab has guide rod mounting holes (22) through which the guide rods extend. The crown slab also has compression washer assemblies (25) which include a pressure plate (26) and anchor legs (27). The pressure washer has a central mounting hole (28) coaxially aligned with the crown slab guide rod mounting holes. The pressure washer has a top surface (29) which is flush with the crown slab top surface (30). The mounting nuts bear against the pressure washer and not against the concrete.