If former spouses hold title as tenants in common, can one force a sale through a partition application?

Generally, yes. Co-owners who hold property as tenants in common, including former spouses who no longer share the same interests in keeping the property, can apply to the court under Ontario's Partition Act to force a sale where they can't agree on what to do with jointly owned property. Courts have historically treated this as close to an entitlement for a co-owner, generally ordering partition or sale unless there's a strong reason not to, such as malicious conduct by the applicant or a valid agreement between the parties that already addresses how the property will be dealt with.

Where the former spouses are still legally married, or the property is still a matrimonial home, family law considerations can layer on top of this and affect how straightforward a partition application actually is, since matrimonial home rules can restrict what can happen to the property regardless of the co-ownership structure. Once a divorce is finalized and any separation agreement has already addressed the property, a partition application becomes a more standard property law tool between co-owners rather than a family law issue. Anyone considering this route should get legal advice on how their specific marital and property status affects the analysis.