Getting Height of boxes

Hello, i was wondering on how i would get the height of a box, going into more detail, i have lets say a character and a enemy, if the enemy is confronted with a block infront of him he would jump up to it not just walk into it, i was thinking of a way to do it but i'm not all that skilled with unityscript i can do the simple things but i lack the skill to do bigger things which i'm learning. back to the question, If there was a raycast of a distance of lets say less than 0.1f and if the height is heigher then 0.7f on the Y axis the Enemy Would Jump, if you could help of have any ideas please answer :)

Thanks.