I'm replacing some dry rot around some window exterior of an older house (built 1920 in the bay area, near berkeley) and I have someone helping me out. They suggested that I use red oak for the trim. The sill is going to be red wood, but I was under the impression that red oak is primarily for interiors. I read that if you prime red oak it still has a higher chance of rotting faster than other woods. This is what the guy bought from the big orange box store:
As you can see, this stuff is 1/4 thick and I'm worried it will warp once it starts to absorb water.
What do you guys think and what would you use, cedar?