First, let’s review what a second mortgage and mortgage refinance are. To refinance means replacing your current mortgage with a new one at different terms. Most of the time, it's not possible to refinance a high-ratio mortgage. Second mortgages are loans that use your home as collateral. You can borrow up to 80% of its appraised value minus the balance on your first mortgage. Most lenders do not extend second mortgages or home equity lines of credit (HELOC) to high-ratio borrowers. To qualify for either product, you must own at least 20% equity in your home.