My washer and dryer are located on the second floor of a two floor townhouse (crawlspace foundation). It's basically a closet that fits the two machines only, with very limited space front to back ( probably 2 inches from the back wall to the backs of the machines, and about 2-3 inches from the front of the machines to the doors.
This place was built in the 1980s, and the dryer duct that pokes through the wall is white and plastic looking.
The current dryer duct runs from a hole in the wall, near the floor, through a hole in the floor (bottom plate is severed), down through some 2x4 wall on the first floor, and based on the location of the exterior vent, runs beneath the first floor (in the crawlspace). The first floor is held up with open trusses.
My dryer duct vent is about 4" in diameter, and the plastic duct appears to be the same. When I found the duct, it looked like it was about to fall into the wall, so I bought a 4" elbow and worm gear clamped it together. I then have a very short length of metal duct that runs to the dryer, that is taped to the elbow and clamped to the dryer.
Certainly, 4" diameter does not fit in a 2x4 wall without some crushing or compressing. I've seen a couple products that use an oval shape to fit within the 3.5" constraint. Do these oval shapes work?
I also realize that I may need to open up walls in my first floor, but would love to avoid doing that if possible.
Having said all this, what is the easiest way to retrofit with rigid ducting?