Through The Roof Meaning

(idiomatic) Rapidly increasing.

Example:   Fuel prices have gone through the roof since last Fall.
2011 October 23, Tom Fordyce, “2011 Rugby World Cup final: New Zealand 8-7 France”[1], BBC Sport:
  With 16 minutes left on the clock and the tension climbing through the roof, Trinh-Duc tried his luck with a penalty from just inside halfway only to push it wide, but the unthinkable now seemed a real possibility.