Originally Posted by
roger wiegand
Nope. Rot resistance. It pretty much only comes in white around here, so unless you have a white house it needs to be painted.
The house we bought 20 years ago needed almost all of its outside wood trim replaced by the time we sold it eight years ago due to rot. Undoubtedly there were better choices the builder could have made for wood species, but the detailing actually wasn't bad. The currently available, fast-grown "white wood" used by most builders simply doesn't have any inherent rot resistance.
The new house has painted WR cedar siding and Azek trim. Eight years on there are, so far, zero issues with rot, expansion issues, or paint retention despite using a dark color at the very limit of the recommendation.