Dryer makeup air source

I'm stealing 7' from the garage to wall in a "formal" laundry room. With it newly enclosed and under air, I'm wondering how best to provide makeup air for the dryer. It vents up inside the wall (via the home-made equivalent of a Dryerbox), through the attic and then either through the roof or gable end, probably the latter. Because of the way the garage/kitchen wall was built, the topmost foot of the back of the wall is open to the attic. I'm thinking of using the stud cavity as a duct, by screening off the opening at the top on the attic side (mostly to keep critters out), and installing a grille at the bottom on the laundry side. There are no firestops to deal with. Any comments/suggestions?

laundry

From your description, it appears that will work, but when you say, "Under air", do you mean it will be connected to the house's air conditioning system, especially with a return duct? If so, then the door must be sealed and self closing to prevent any possibility of carbon monoxide flowing from the garage into the house.

I piped a peice of 4" PVC tyhrough my outside wall into my laundy / furnace area. It should have been 6" but I only had room for 4".

HJ -

Yes, it'll be airconditioned, but I haven't yet figured out how to route a return air duct; I was going to see how it went without one. Like most Florida slab homes, there's one return at the air handler, and they depend on general circulation for the return. (It doesn't work all that well at the extremes.) The room itself is sealed from the garage, although I hadn't planned to make the door self-closing. This is a work-in-progress; most design is done with the hammer in motion.