I'm refinishing my basement and the inspectors informed me I need a fresh air supply vent added to provide combustion air for the furnace and hot water heater. They told me I had 2 options. One was to have a six inch pipe from outside dumping air near the furnace the other is to tie a six inch pipe from outside into the cold air return for the furnace. I'm not sure which way to go. Also either way my floor joist are only 2x8 (7.5inch) so cutting a six inch hole in them would be like cutting the rim joist in half. Any heating cooling people out there who can tell me how this is normally done and what materials are usually used for the pipe, cap, and how to insulate?