What holds the chimney cap in place?

[Bill Stock]

The chimney cap blew off in the big wind. Looking at it, it looks like friction fit as there is no evidence of screws or a collar.

There is a metal sheet that sits on top of the chimney with a collar that extends down into the bricks. This part seems to be glued in place. The pipe comes up flush with this collar and there is a thin gap between the collar and the outside of the pipe. I assume the cap is supposed to fit in this gap, but it is sitting up there now and there is absolutely no friction. It is not as tight as it could be, since the flange that meets up with the sheet on the chimney is a little warped from the fall.

I did not want to bang it around too much until I had some clue what I was doing.

[Hellrazor]

Most metal caps are attached with set screws that lock the cap onto the outside of the liner.

[Bill Stock]

Most metal caps are attached with set screws that lock the cap onto the outside of the liner.

Mine looks a bit like this one:

http://www.fireplacemall.com/Chimney...r_air_ins.html

Except this one has a metal ring at the very bottom, whereas mine only has a crimped stove pipe. I assume some folded over metal added the extra thickness required to make it friction fit. I'm not sure if the metal ring fell down the chimney (likely) or got blown away. Even if I could find the part, it would be unlikely to stay attached. Looks like I need a new Chimney Cap.

[Hellrazor]

"If you are installing a top mount chimney cap , you can use an adhesive supplied with most chimney caps or Tapcon masonry anchors. "

That was in the install guide on the link you supplied. Tapcons would be used into the brick and not the liner. If you use adhesive or caulk, it should be fire rated.