I am unclear as to why Rashi is so lengthy, but here is the translation, as per request:

The wall of the Ulam: The lower section of the outer wall -- the width of the foundation plus the threshold, the upper section from above the arch of the entrance -- the thickness of the wall that rises up to a height of one hundred Amos, apart from the width of the area of the Ulam itself (I do not know why Rashi uses the word "Kipas" here), which measures eleven Amos besides the thickness of the wall.

B'Virchas Kol Tuv,

Eliezer Chrysler