I have a 15 year old house I have lived in for 10 years. I live in a dry climate and my house does the same thing. It can be annoying but to ease your mind I have been told that it is the expanding and contracting of the lumber your home was built with. They say to humidify your house to keep the wood at an even moisture. This is supposed to calm alot of the noise. I think I will try it too. I do notice when it rains the noises are minimal. Hope this helps.