Financially it would make more sense to have your 2nd mortgage on a 15 year loan - if you can afford it. In the long run, you'll be saving a lot of interest paid by going with a 15 year vs. a 30 year. However, since it's a 2nd mortgage, the balance probably isn't that much compared to the 1st. But overall, you're going to be saving money by going with a 15 year. The reason is twofold: 1) The interest rate is lower. 2) You'll be paying a lot less in interest - due to the fact you're only paying on it for 15 years instead of 30 years.