Constructive interference results in a wave with a greater amplitude than any of the component waves.
In fact, constructive interference occurs when two (or more waves) arrive at the same point in phase. This means that the waves add together, and the resultant wave is bigger than the original waves. On the contrary, when two (or more) waves arrive at the same point out of phase, they cancel and destructive interference occurs: the resultant amplitude in this case is zero.
