Is a drainage plane really necessary in the PNW?
I am building a house in the PNW region, roughtly 30" rainfall per year. ICF foundation, SIPs in 1st and 2nd floors. We will be wrapping the house with a WRB.
We are planning on vertical shiplap siding - it will be a natural wood product. I have read quite a bit about siding and many sources emphasize the need to have a "drainage plane" between the siding and the skin of the house. I mentioned this to my contractor and he had a very strong reaction against it. He said that in his many decades of building houses he has never done this, and never had a problem. Furthermore, he has done remodels of homes that are 60+ years old and has found that the "paper" underneath the siding is practically intact.
His conviction is so strong, I am wondering if all the building science literature on this subject is over-engineering.
Does anyone have practical experience on this matter? I.e. When is a drainage plane necessary, and when it is a "nice to have". I know the theory, but curious about actual experiences.