6x6 Deck post repair, Joining two 6x6 posts

Question

I need to replace a 13 ft high, approximately, 6x6 deck post due to dry rot on bottom half of the post .

The deck sits around 10 ft high from the ground and rest of it [post] is above the deck floor connecting rails. The 6x6 post sit on the concrete with metal bracket.

Replacing entire 13 ft high post would be the optimum solution but would require a lot of extra work, like removing some of the deck floor board, detaching rails on the top, removing side cover panel which is bolted into 6x6.

Question:

Can i get away with cutting the bad rotten part of the post (lets say about 9 ft from the bottom and replace with new post) so basically joining two post vertically using metal braces? or please suggest any other feasible solution.

Answer 1

Dry rot doesn't really exist but I'll imagine you said brown rot.

https://en.wikipedia.org/wiki/Dry_rot

It sounds like your post is not 6" above grade.

I'd probably just put a 6x6 sonotube into the ground and have it extend up to where the wood is still good. Add a Simpson CB66PC and bolt the post back into it.

https://www.strongtie.com/classiccollection_architecturalproductsgroup/cbpc_base/p/cbpc

Answer 2

Can you? Technically I'd say "yes" but with the disclaimer that you should not and this would likely not pass inspection (and I wouldn't do it because it's difficult to do safely, not something you'd want to DIY).

It is difficult to cut 6x6 posts in a single pass, most builders will cut with a circular saw with max depth of 2", and cut from all 4 sides and then finish the center of the cut with a hand saw. No matter how you cut the posts, you must be extremely straight/flat because any angle could cause the top of the joint to slide off the bottom. Deck loads can vary a lot, from hot tubs with high static weight to parties and wind with high dynamic weight.

Next, to prevent that slippage your solution needs some kind of support which at a minimum would come from wood blocking on at least 2 sides (I would never recommend this, but I have seen it discussed). The bare minimum I would personally accept would be 1/8" steel on all 4 sides with at least 4 lag bolts/screws on each side (2 above, 2 below).

Last, most ways you could construct this would be very obvious and ugly. The color of new wood is very different from aged deck wood, old wood can shrink by quite a bit over time, whatever brackets or blocking you end up with will be obvious partway up the post height, it will just look amateurish.

Replacing the entire post is difficult, but it's definitely the right thing to do.