For nearly a year after we moved into our new house, we heard thumping in the attic. It was most distressing. Finally, I happened to be in the back of the house one day and the breeze was blowing. I looked up at the roof and I saw one of the metal caps on the attic vents dancing in the wind. When it got done dancing, it "thumped" back down.
I called the Villages warranty office which dispatched the roof vent crew and they found that of the four screws that were suppose to hold this cap in place, there was only one. They screwed it and the no more thumping.
Dancing with the vent~~~