Replies

1. 
   duradeknw | Mar 24, 2011 07:20pm | #1

   treated posts and aluminum wrap

   ACQ is known to corode many metals, but you were correct in using a seporator.  I believe since building paper still breathes a small outgasing cause by drying or ambient humidity may present contribute to your  problem. You might find standard duct  tape in two layers on the back of the metal where in contact will prolong the life also the use of stainless steel nails as well.  A heavy zink coated metal will outlast the aluminim but stainless steel would be the top choice of metal.  Hardie board siding and stainless steel fasteners is a good look, economical and with the minimum thickness of 1/4 profile, adds only a 1/2 inch to your post.

   Washington Alaska Roof Systems, Inc - Duradek Northwest

2. 
   DanH | Mar 24, 2011 07:23pm | #2

   You could use some sort of sheet plastic and plastic corners, but it wouldn't look like a plain post then.

   I've seen slide-on plastic sleeves for 4x4 posts, but not  6x6, though they may be available somewhere.

   Or you might find someone who'll fabricate two plastic Us for you -- simple enough for someone with the plastic stock and a bending brake for thermoplastic.  (I've seen this done for commercial work, so there must be people who do it..)