Repairs may be made with­out fil­ing an appli­ca­tion or obtain­ing a per­mit, unless such repairs amount to a “sub­stan­tial improve­ment”, the cost of which equals or exceeds fifty per­cent (50%) of the actu­al cash val­ue of the struc­ture either, (a) before the improve­ment is start­ed, or (b) if the struc­ture has been dam­aged and is being restored, before the dam­age occurred.