California redwood? from California ? You got to be kidding? Its about as decay resistant as white pine these days. THERE IS NO NEW CUT USA REDWOOD THAT IS DECAY RESISTANT TO ANY APPRECIABLE DEGREE, PERIOD. If I had a dollar for every 5-10yr (and sometimes less, alot less) so called decay resistant redwood deck i've seen rotted up here in Ca. I'd have ...umm 10-12,000 in my pocket, easy. And if you have a live or dead tree anywhere withing 50 ft of a redwood deck bleeding fungus spores by the billions and yes they put out billions of spores per fruiting growth...good luck with CA. grown new cut redwood.
The trick to redwood decks is, treat them every 2, two, two,two, two, two, yes TWO years with pretty much ANY wood preservative and they will last 30 years easy(of course weather splitting looks awful, lol).
But if you do not treat the substructure and bottom sides of EVERY board and end cut, kiss that lumber good-bye.
If you really like redwood, get imported, like Malaysian or from where ever, or contact a demo/salvage company often they will save and stock the old growth redwood because of its value. But you will have to have it resawn to suite most modern designs.
The only real decay resistant redwood in the USA is old growth, and its no longer harvested in any degree to cover the general demand for the so called "decay resistant" redwood.
Calling new growth redwood decay resistant is just laughable.