Damage beyond repair. When a nonconforming structure or use is destroyed or damaged by fire or other casualty or an act of God beyond repair, the nonconforming structure or use may be rebuilt. The Planning Board shall approve a site plan for the rebuilding. The new building shall have substantially the same floor area as the one destroyed. The Planning Board may approve a change in location on the site if it increases side or front yard dimensions, reduces nuisance characteristics or assists in carrying out the objectives of this chapter.