THE NOISE IN THE ATTIC, or is it the windows?

I was called upon a few days ago to come out to a lady's house and investigate the "noises in the attic, and sometimes the windows".

After thoroughly looking around the house, up in the attic, and scrutinizing several of their new vinyl replacement windows, (about 1/2 hour after I arrived) I finally heard the first of the noises to which she was referring to. A crackling noise appeared to come from somewhere in the attic, and then suddenly, a much louder pop, or bang type of noise. The lady jumped and grabbed my arm.. "There, did you hear that?" she said. Hmm, not only did I hear it, I FELT it! (my arm may be black and blue soon). Back up in the attic I go. Soon, more noises, and it was becoming apparent what the source was. Any guesses?

Back down, and now we could hear some small noises that seemed to be coming from the rear window in the dining room, which was quite large. She said "Now you see I have a symphony of noises, and I am not crazy, right?" I agreed.

This house was West facing, and the sun was coming up in the rear (about 10 am).

The noises we were hearing were a result of expansion that most likely happens every day when the sun comes up. The loud banging noise was apparently coming from one single truss in the attic, that when it expanded, was rubbing against another framing member, and when  it expands enough, the pop can be heard. The windows as well were expanding in the morning sun, and crackling against their framing and insulation.

I assured her that these noises are quite normal, and that she probably experienced them in the morning, and again in the evening, when things started to cool down again. Why don't the noises occur all the time? I believe the answer is that they occur because of temperature differentials in different materials, as they are heating up or cooling down at different rates. It is most likely more pronounced when the sun shines in the morning, and starts heating things up. Usually, there is not much that can be done to stop this phenomenon from occuring. However, large popiing noises can sometimes be eliminated or quieted if they can be pinpointed. Sometimes simply sliding a piece of rosin paper in between noisy framing members will do the trick.