Do spells that are Radius but not a sphere extend up and down also or are they just say 5ft thick?

@JeremyECrawford Do spells that are Radius but not a sphere extend up and down also or are they just say 5ft thick?

— Steven Connor (@Mazoshi1987) October 28, 2016

A radius in the game extends in every direction, unless a feature says otherwise. #DnD https://t.co/TN813HnSVn

— Jeremy Crawford (@JeremyECrawford) October 28, 2016