Post protector (or something else) to extend life of existing deck 4x4 posts?

Question

I'm resurfacing a deck. It was built 19-20 years ago. Had an inspection and was recommended to replace 4x4 direct-bury posts with 6x6 with concrete piers/footings. This work isn't as simple as jacking the deck and digging (sistered boards against 4x4s, posts right against foundation, stone pavers and drainage pipes to deal with; not to mention 30"x22"x22" dig with 70 bags of concrete). The posts are currently fine after 20 years. I'd rather just leave it and deal with replacement in 10-30 years. But is there anything I can do with existing buried posts to extend the life? There are some related answers (only 1 for existing, and none discussing post protectors) and looks like my options are:

• post protectors - no mention of using these post-construction to extend life
• blueskin around the posts
• concrete - not recommended because of 'collar rot'
• packed gravel around post - haven't seen any mention of this

Would a post protector work to extend the life (I would probably have to cut it to get it around the existing buried post) or would any other alternative work better? at all?

Post Protector

Answer 1

This answer assumes the deck is in a good shape and the recommendation for post replacement was not from the City inspector for permit concerns.

I may try to open the buried post, let it (skin) dry then coat it with a layer of hot asphalt (in liquid form), the more the asphalt is absorbed into the wood, the better the performance of repelling the water/moisture. Clean gravel is a good idea, but if the existing soil already posses free-draining ability, I won't bother with it.

Since the deck has already stood for almost 20 years without problems, I won't replace the post unless it has damages such as cracks, or aging (wood softening below grade). If necessary, add a bracket on the beam-post joint, or a diagonal in between posts can be as effective as a larger post.

Answer 2

For anyone wondering what I ended up doing: I ended up rebuilding the deck and replacing the 4x4s with 6x6s. Because the old footings were buried I still had this problem. I applied 3 treatments:

• extra wood preservative
• a coat of flexiseal
• a heat shrink tar-like product called PostSaver that is installed below and above ground level.

I'm very confident I won't have the collar rot that I saw on the older build.