I'm seeing a crack in the corner of the ducts. Can I just tape it shut with boxing tape or is there a better way to do it?
Also, one register in an unfinished area is turned off but I can feel it leaking air. I looked inside and there's clearly a gap letting air past too. Can I also just cover the register in reflectix and tape that shut too or is there a better option? Thank you :)
Aluminum duct tape (the one for air ducts not the duck tape) is the way to go. It usually has a paper back you need to remove from the tape because it’s super sticky. If you use regular tape, it will unglue with the heat.