I have a three month old home with two gas fireplaces that use a common chase area to route the flue pipes to the roof. One is securely mounted, but the other is not, and when the wind blows briskly, it vibrates and causes a resonance like a washer spinning out an unbalanced load. Of course this is usually at 2 AM. The pipes go through a shed roof area that has zero access from inside the house. Ideas on how to fix something like that? After reading a few other posts, it occurred to me that I might be able to weight the pipe to change the frequency it resonates at, but if it is already not that secure, even if I quiet it down that way, will it just move the problem elsewhere?

Thanks!

Jim