For an amount as low as that I would suspect there will be cheaper way to find the finance, such as a personal loan or credit card. However if you were looking to pay off debts/purchase a new vehicle and take an overseas trip and needed around $40,000 then refinancing would be a good way to do it usually.

Another thing to remember is that if you only built the house last year then you are possibly tied in for a minimum period and would have fees to pay if you refinanced. You could add an extension onto your loan to raise the finance but remaining with the same lender, but usually they will have a minimum amount that they will do that do and it's often in the region of $25,000.