Replies

1. 
   DanH | Mar 27, 2011 06:43pm | #1

   My take is that redwood will last longer in other than an arid environment.  Neither will last forever, though.

2. 
   Piffin | Mar 27, 2011 09:39pm | #2

   Douglas fir is far stronger and has decent rot resistance esp in CVG heart

   Redwood is weaker and softer. condition varies a lot more between all heart and new summer wood re rot resistance.

3. 
   dgale | Mar 29, 2011 12:00am | #3

   Depends on the quality of the redwood - most second (or third) growth redwood has more sapwood than heartwood and doesn't have nearly the rot resistance that old growth had.  Check the quality of wood, density of growth rings etc. and judge for yourself how long it will last.  This in not just true of redwood but for any type of post - the quality of the specific wood will ultimately determine its longevity.

   It's not exactly clear to me how you are going to use these posts - are they going to be partially buried like a fence post?  You mentioned priming the fir - are they going to be painted?  If you're going to bury entreated wood then I advise treating the portion to be be buried with Jasco.  If you're going to paint them then a good prime and paint job will go a long way toward longevity.  Also, another wood to consider is Cedar - we get good quality locally milled western red cedar posts around these parts that I use for fence posts.  I don't like the look of pressure-treated wood for fences regardless of how long it lasts, good quality redwood is prohibitively expensive (usually salvaged old growth) and cedar had good rot resistance - certainly better than fir.