Most Helpful Girl
That's an interesting thought0
Most Helpful Guy
Actually, if you see the origin of the word "building", it is byldan (Old English) and bilden Middle English.
In modern English, it is respelled and moulded as building.
Furthermore, the suffix doesn't always mean present continues verb but in fact, a suffix used to form nouns from verbs, and signifying the act of; the -> result of the act <- as, riding, dying, feeling. It has also a secondary collective force; as, shipping, clothing.0