A couple of situations I have come across are in regards to septic issues on a duplex (side-by-side dwelling) property as well as additions to a duplex.

In regards to the septic issue, even if one side uses the septic and the other side of the duplex is tied into the municipal sewer system; if the septic needs to be replaced the cost is spread evenly to both sides of the duplex. It is important to have the bylaws looked over and changed to reflect who pays for what in the case of repair.

In regards to additions, you will want to have the unit entitlement changed should one side of the duplex add an addition. If the bylaws are not amended, if the roof needs repairing, both owners are paying half of the bill. The unit entitlement, on Form V or Form 1, depending on the age of the building.

Steps to changing bylaw and unit entitlement
- obtaining a unanimous resolution to change the habitable area and unit entitlement;
- creating a new Schedule of Unit Entitlement in accordance with the unanimous resolution;
- making an application to the Land Title Office to amend the unit entitlement, which requires the submission of the following documents:
-the new Schedule of Unit Entitlement:

Hope this helps! Always consult a lawyer for professional advice and this article is merely my opinion.