Will your renovation result in your house violating the municipal zoning by-law? Has your neighbour agreed to grant you the right to travel over a portion of his or her property? Have you agreed to a severance?
If so, you may need a lawyer to assist with an application to your municipalities Committee of Adjustments for Planning Act "consent".
I have successfully appeared before multiple Commitees of Adjustment in Simcoe County on matters such as these. Please contact me for further details about this area of practice.