Class A chimney roof guy kit ?

First question would be, how far down from the peak of the roof the chimney is. on a 12/12 pitch, I'm assuming it's real close if you only have 5 or 6 feet of exposed pipe. If your more than 4 or 5 feet down the roof from the peak, I'd suggest a roof brace kit. You know, it's one of those things....your thinking about doing it, it can't hurt to do it, (those roof brace kits should only run about $100) and you know what will happen if Murphys law finds out you didn't do it. An ounce of prevention and all that.

I agree with Franks, I have a 7/12 pitch roof, and my chimney exits about 7 feet from the peak of my roof with about 5' of pipe exposed. When I initially installed the chimney, it seemed pretty solid without the roof support, but with the support it will not move no matter how much force I put on it. The 100 dollars spent is pretty good piece of mind when you and you're family are sleeping knowing the chimney isn't going anywhere.