Abstract: The bubble expansion velocity is an important parameter in the prediction of gravitational waves from first order phase transitions. This parameter is difficult to compute, especially in phase transitions in strongly coupled theories. In this talk, I will present a possible way to estimate the wall velocity for phase transitions with a large enthalpy jump, valid for weakly and strongly coupled theories. In this limit detonations are disfavoured, but wall velocities are not necessarily small if the amount of supercooling is not too limited. I will finally test the results against those obtained in earlier holographic time simulations.