I have someone who is installing a medicine cabinet. When he cut a hole in the wall, there was a cast iron air vent pipe blocking the site for the cbinet. His solution was to cut the pipe to remove the section that is in the way and then rejoin the pipe using a (rubber) flexible boot. My question is whether this will become a problem later. In fact, I have read that it is against code to install a boot behind a walll. Is that only in the case of water pipes? Does it also apply here for a vent? Is trouble on the horizon? Thanks.
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