Here are some pictures. The house was built in 1989. It's in Minnesota.
Panoramio - Untitled photo
Panoramio - Untitled photo
Panoramio - Untitled photo
I was just up in my attic and there are two rows of chains that connect the rafters to the joists. The rows run parallel to the ridge and the chains are 2 or 3 feet apart. But the chains are slack, not tight, and they are light-weight chain, like dog chain.
Thanks!