Question: i have purchased some triple wall pipe for my woodstove chimney from a private party. the pipe set up is complete except for the T pipe exiting the wall on the outside. obviously, the inner pipe needs to be capped, but what about the outer wall? is there a cap missing that encloses the entire bottom of the T joint? is there a separate cap for the inner and outer wall, or one cap that closes both? Answer: Usually there is a cap on the bottom of the insulated tee, although it is possible that this cap is built into the support which the tee sits upon. Check the brand name of your piping and see if you can get a manual or parts list to confirm that you have all the pieces. If it's triple wall, it's probably either: Duravent, Airjet or Metal Fab. Please keep in mind that it is NOT safe to use ANYTHING except the parts made by the same manufacturer who made your chimney.