You can combine a revolving home equity line of credit with a fixed term mortgage, then finance part of your home purchase with the HELOC and part with the mortgage loan. Most lenders will require a minimum down payment of 20%. Alternatively, if you want to use a HELOC as a substitute for a mortgage, you'll need a down payment of 35%. You can still finance your home up to 80% of its purchase price this way, but the amount above 65% must be on a fixed term mortgage.