Can I build a structure or addition over a utility easement registered on my Ontario property?

Generally, no, not without the consent of whoever holds the rights under that utility easement, even though you hold title to, and pay taxes on, the land it crosses. A registered utility easement, for things like electrical lines, gas mains, sewers, or drainage, exists precisely so the utility can access, inspect, and repair its infrastructure when needed, and building a permanent structure over that area can interfere with exactly that ability.

This surprises a lot of homeowners, since they assume that owning the land means they can build anything on it as long as it meets zoning and building code requirements. But the easement is a separate legal right layered on top of your ownership, and it can restrict what you're actually allowed to build in that specific area regardless of what a general building permit might otherwise allow.

Before adding a deck, addition, shed, or any other structure near a registered easement, check your property's title and survey for the exact location of any utility easements, and contact the utility or rights-holder directly to confirm what is and isn't permitted. Some structures might be allowed with conditions, while others will be flatly refused, and building without checking risks having to remove it later at your own cost.