I'm rebuilding a plenum for my air handler. It goes from the garage through the attic. I'm ok with the specifics of sealing it, but I can't figure out how to get the backside of the air handler sealed. There's only about .5 in to an inch of space for a 17" span. What's the best way to get mastic back there? Hot dog roller? via /r/DIY https://ift.tt/2IhZjR3
