Sorry, this ended up being a lot longer than I thought it would be...

We had a cedar pergola built almost 10 years ago and recently I have noticed a couple of the posts are getting some soft spots at the bottom (one in particular that sits on top of the concrete patio). I've wanted to add some brick around the bottoms of the posts for awhile and now it's become a priority to try and shield the bases from the elements. I've removed as much of the rotten wood as possible (still plenty of ground contact of solid wood) and filled it in with a structural and waterproof filler. I also plan to re-stain and seal everything before covering it up with the brick. My questions relate mostly to that process as I've never done masonry work of any kind. I have a pallet or more of bricks left over from when the house was built, so that part is taken care of.

Assuming everything underneath is sound and sealed, I assume I still need to wrap the posts with some sort of barrier. The brick will not be load bearing, but I do want it to be somewhat durable because I have kids that don't pay attention with bikes, skateboards, soccer balls, etc.

-Do I just mud the first layer directly to the existing concrete patio?
-What kind mortar should I use?
-Should I put the bricks right up against the post or do I leave a small gap?
-Should I have some weep holes, assuming water will get in from above at some point (a couple of the posts have some small splits running vertically)?
-Anything I'm missing, or not thinking about?

Plan to go about 2 feet up from the ground with either stone or split bricks top, sort of like these pictures.

I was thinking abut more about this at work today and was wondering if I should put a waterproof adhesive under the first layer of bricks to prevent/minimize water penetration through the patio and bricks.

Just have this feeling that the way I'm thinking about this will only make it worse, trapping moisture in and around the post. Would like to get going on this ASAP since we've had such dry and hot weather, so the wood is about as dry as it will get at this point.

What's the purpose of adding the brick veneer? Is the intention primarily to try and block out the moisture? If so I agree with your most recent conclusion that this is likely only going to make it worse. The mortar is going to be water permeable and hold moisture against the wood.

I have a cedar pergola with 6"x6" posts buried 2' in the ground on my paver patio. I had some cedar trim (at ground level) around the posts and after 5 years the trim started to rot. I noticed some rot in the cedar posts where the trim held moisture against the posts. My solution was to remove the wood rot, and add in some wood filler in the rotten areas. To add long term rot/insect protection I did some research and found out that borate is commonly used as a wood preservative. Borate rods are used to protect wood where moisture is present. I purchased mine from a log home supplier (common brands are Bor8 or Cobra Rods). The rods are inserted into the wood member and it should protest the posts for 10 years.In addition for extra protection I added some borate paste topically to the wood posts (common brand name is Tim-Bor). Due to the costs of the commercial products I made my own paste at home using glycol, borax, and boric acid (there are recipes available online). I then resealed the posts with a wood sealer and covered up the treated areas with cedar trim.

Purpose is two fold. One, I think it would look nice and have a crap ton of bricks in my garage. I have wanted to do something like this since we had it built to be honest. I just never had the time. Two, I now want to hide the bottom of the posts because of the repair work I've done to this point just doesn't look all that great.

I will look into the borate method, thank you.

Frustrated overall because we paid extra for larger center cut cedar posts because of the wet and humid climate, and less than10 years the problems I'm having is pretty extensive. Ultimately I'll have to either have the posts replaced, or at least repaired and put up off the ground onto some sort of metal or poly post mount. This is one of two posts that sit on the patio, the other four are in the ground/concrete. I'm starting to see a little bit of damage on a couple of the others, but one in particular is concerning.

Regarding the moisture inside and under the veneer, that's why I asked if I should wrap in Tyvek or something similar before building the brick up. I also planned to seal the top layer's seams that will actually touch the posts with something waterproof (sanded grout, silicone, etc.).

The second pic was from Kenneth in McKinney that did exactly that at our home in Tyler. I don't recall there being any sealing or any kind of moisture-proof treatment. Just mortared all around, no weepholes. Probably not much different than an exterior wall. You might Tivek the post?

When we added a porch the framers had 18" round steel posts fabricated that supported the wood 8x8s. Then the stone guys wrapped up to the wood.

Completely different suggestion offered to me in a conversation at work yesterday.

Since it will be covered up anyway, apply/wrap the damaged/repaired part of the post with something that will harden and become waterproof like FiberFix, re-stain, add a waterproof barrier, then brick over that. Idea makes sense, but not sure about using "as seen on TV" solutions.

Going back to my cedar pergola, when it was first installed I had the contractor wrap the post in Tyvek (underground and 4" above grade) however my experience after a few years was that the water found it's way behind the Tyvek (from the top) and IMO made the situation worse by keeping the posts wet for longer. That's why I ended up using the borate rods because they disperse borate when the wood moisture content is above a certain level (around 20%).

There's no surefire way to prevent water from entering between the brick and the wood. I don't think it's a bad idea to wrap the existing pole and then brick, but it's not a forever solution.

I realize the post already exists, but in a perfect world, the wood post would rest atop a CMU base and then you brick around the base. This is an overkill drawing, but something like this.

I agree, and know that wood outside is never permanent. Had I known what I know now when it was built, I would have done things differently, for sure. I even considered cutting a couple inches off and putting in a base/anchor of some sort under the posts and then brick around them but I'm already making a mound out of a smaller mound.

I would shorten them and add some metal post bases to keep them from wicking water off the concrete. Then wrap in cedar 1 x material.

Another thought is to put roofing tar on the post to prevent water ingress. Then put bricks around the tar.

My dad did this with an old fence. Put tar on the post from the bottom to 1' above the ground. Sloped the concrete away from post. Kept the post dry and helped prevent rot.

~egon