it differs from council to council...i think becoz ur neighbour is doing a 2 storey whereas everyone is 1 storey oni..so in away ur neighbour obstruct sunlight, views, and enroach ur privacy..from 2nd storeyy maybe can see ur jamban or what.

so when u all approve, later cannot do anything mahh..coz everyone edi gave consent...this follow bylaw rules liao...in UK n Aussie they are very strict like this

same lor..u extend front and back also will obstruct and intrude ur neighbours wat..right left front back..hence the 20m radius. in australia, if ur new windows location looking into a neighbours existing windows oso cannot...really strict. mbpj advcance liaoo..follow developed nation standard edi