I purchased new washer dryer to replaced the old one which was hooked up to 3 inch venting (it's a condo unit and the washer/dryer was only 1.5 Cubic feet). My husband would like to change it out to 4 inch hard aluminum ducts but it will not fit in the wall where it runs up to the attic and then out. He tells me that the hole in the attic, that you drop the run down, is in a 2x4 and can not accommodate a larger hole. ??? Any thoughts on how to get a 4 inch pipe in that wall - I've read about shaping it into an oval possibly for the wall only portion. Thanks for any thoughts...