A divider strip and method of using same which facilitates the provision of seam areas in terrazzo type flooring structures. The divider strip comprises an elongated thin, generally U-shaped body portion including an outwardly extending mounting flange at the distal end of at least one leg of the U. A resilient plastic material is received in the channel area defined by the body portion for maintaining the shape of the strip and for keeping foreign material from entering thereinto during the floor construction work. The strip is desirably mounted by means of the mounting flanges to a base floor in an inverted position and terrazzo flooring material is poured over the base floor on both sides of the divider strip to a level substantially equal to the height of the divider from the base floor. Following pouring, the terrazzo surface is ground smooth and, in the process, the closed end of the U-shaped body portion is ground away to expose the resilient plastic material in the channel area. The plastic may then be removed and the channel area filled with a color impregnated or plain grout-like material in order to complete the seam. The ends of the divider strip include means to facilitate an interfitting locking relationship between the divider and other, similar dividers when they are to be spliced in a straight line end to end relationship.