When you are interested in buying a new house, if you are like most people, you will need to take out a mortgage. What people may not be aware of is that with a conventional mortgage if you don't put down at least 20% of the cost of the house, you will have to pay for expensive mortgage insurance. To avoid paying this insurance, you should not consider buying a house until you are sure you can come up with at least a 25% down payment. Not only will you avoid mortgage insurance, but, you'll probably get a better deal on the mortgage.