I have lived in 2 story house in Northern California since 1999. This house was built in 1989. Basic stucco over frame type building. I do have a large attic that was not finished. In 2007 I decided to use the space and we put down some ply-wood just for storage purposes. Recently I have noticed some real LOUD popping noises coming from the northwest side of my house. Sounds like closer to the outer walls or roof line. It is loud. Usually the pops come at night, or in the morning. I have been reading about the "temperature change" possibility. We don't have "extreme" weather conditions here. I live right outside of San Francisco. It gets warm here during the summer on occasion but its not constant. Mid 70's- mid 80's... I just never heard it this loud or this often. I have noticed the creaks in other parts of the house, but like I said not coming from this one location or certainly not this loud. Should I be worried about structural issues? I am the second resident and I am not sure about the builder if they were good and bad. I remember initial house inspection said the house had an excellent solid concrete foundation, so not too sure about the "settling" factor. Any suggestions or directions would be greatly appreciated.