Can I use my house as collateral without my spouse's consent to finance a business purchase?

Generally no, if the house is a matrimonial home under Ontario's Family Law Act. That Act restricts one spouse from mortgaging, encumbering, or otherwise dealing with a matrimonial home without the other spouse's consent or a court order, regardless of whose name is actually on title — meaning even a house owned solely by the spouse seeking financing can still be a matrimonial home requiring the other spouse's cooperation before it can be used as loan collateral.

Lenders who take real property as security are generally well aware of this requirement and will typically ask about marital status and request the other spouse's consent, or an acknowledgment that the property is not a matrimonial home, as part of their standard closing documentation, precisely to avoid a mortgage later being challenged. Trying to bypass this by not disclosing a spouse's existence can expose both the transaction and the lender's security to a later challenge. Anyone planning to pledge a home for business financing should address this directly with both the lender and a lawyer before signing anything.