I would think that WA with all it's rain would cause problems with wood and metal against the ground. You must have good drainage where you are.......Aart, oddly enough I have never had an issue with stuff rotting away (well other than osb that never got painted), so I'm hoping that continues. I wish I could still access my old coops before I moved as they are built in similar style and are approaching 15 years old now and some are still being used. So as long as I can get close to that amount of time out of these I will be happy, and by that time I hope to have bigger and better options available......
Looking forward to watching this project progress!