Full-scale structural deflection tests were conducted on floor sections with 2"x4" , 2"x6", and 2"x8" joists at four different stages of construction. Stage A was joist alone; stage B joists plus 1/2" plywood subflooring; stage C, stage B plus 25/32" oak strip flooring laid parallel to the joists; and stage D, stage B plus oak strip flooring laid perpendicular to joists. Results show substantial decreases in deflection due to stages B, C, and D. Stage C resulted in the stiffest floor for all sizes of joists followed by stage D and stage B in that order. Decreases in deflection also varied by size of joist, showing that as the size of the joist increases, the effects of the added construction components decreases. Average decreases in deflection are shown in Table 11. / Master of Science