Financing a home addition without refinancing can be achieved through various methods. One approach is to consider a home improvement loan, which is specifically designed for renovation projects and doesn't involve refinancing your entire mortgage. Another option could be to use a cash-out refinance only for the amount needed for the addition, rather than refinancing the entire mortgage. Additionally, exploring personal loans or a home equity line of credit (HELOC) are also potential options for financing a home addition without having to refinance your existing mortgage.