Is it possible to shim porch post?

Old 02-10-20, 09:40 AM
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Is it possible to shim porch post?

I have a roughly 8x10 foot front porch that is connected to the house on two sides and then sits on a 6x6 post on the opposite corner (which also holds up the small roof above it for covering). This post then sits on a concrete footing (~18 x 18 inches), per the attached image.

Over the years, it appears that the footing has settled by ~2 inches.

I know one option is to jack the post, jackhammer out the current footing and then put a new footing in (the post and structure look good and assuming upon closer inspection they still are) - but is there an option where I can cut the screws/nails on the current post bracket - then jack it up by 2 inches and put a new metal shim / bracket in the seat? The assumption here is that the settling is pretty much done and then just looking to correct it with minimal excavation. Any help on if this path is valid and what solutions exist is much appreciated.
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Old 02-10-20, 04:30 PM
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One option would be to replace the post with a new, longer one. The footer should be at or above grade so the wood post is kept out of the ground and away from moisture. If you can't re-grade to get the wood safely up in the air then re-doing the footer is an option although a lot more work.
Old 02-10-20, 04:41 PM
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I would probably cut off / remove that old post base and bolt a new Simpson 66PBZ down. They have a 1" thick metal standoff inside them to keep the bottom of the post above grade. I suppose you could then insert some flat iron shims between the post and the standoff. But replacing the post with one that is the right length would be best.
Old 02-10-20, 06:22 PM
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The post itself is tied into the deck (~24 inches above grade) and also supports a small roof section (~8 feet above that). I agree pulling the post and putting a longer one is viable, but may not be easier then just removing/replacing the footing (and then we can be 100% the ground is solid (as this is what has sunk 2 inches as both the deck and roof have the same slope down).

All that said, I am fairly confident the ground is settled now (no movement in years) - and wanted to see if there was an easier way through shimming that was still code compliant?
Old 02-11-20, 02:04 AM
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Generally with foundation type things, the hardest way is often the best way, just because it sucks to have to go back again and redo the work in a few years. With a shim you are going to get moisture between them, so it would be best just to redo the post to longer length and have it be a 20 year fix instead of 2 years.

I know it is a 1 day job instead a 1 hour job, but it will also last 20 years. If you sell your home at some point, then an inspection might pick that patch job up too, and you will be redoing it.

Just some thoughts...I fully understand taking the easy way out.
Old 02-11-20, 02:43 AM
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I would just cut off the screws, jack it up and then add your shim.

Once you get it jacked up check the bottom of the post for rot.
Looks like it is a pressure treated post so the centers can rot out.
So I would check for this, also check the area around the screws.
And the full length of the post, if it is rotted or starting to rot elsewhere then replace it.
If it is rotted out then you will have to come up with a new plan.

I would probably use a wood shim but with the grain running parallel to the saddle's metal sides so that if it should split in the future it cannot go anywhere,
I would use fir as it is fairly non compressible and is rot resistant.
Also it should be the same outside dimension as the post so that water cannot sit on top of the shim.
I would also put several coats of end cut preservative on it.
Also would not hurt to use exterior construction adhesive it will not only hold it in place but also add some weather protection.

Looks like the sides of the saddle are high enough that you can still get some screws into the old post after the fix.

I know that replacing it is the best solution but sometimes it is just not practical.

Old 02-11-20, 08:28 AM
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In general, I am after a code compliant fix - and if shimming in some way is not viable - I would just move to the other options.

Right now, if I shim, I would be thinking of putting some shim like this Simpson CPS6 Standoff or aluminum plate cut to size (I have plenty of T6061) and then captured on two sides with something like the Simpson RPBZ. The issue here is that I would need three (3) of those CPS6 shims to get to the desired 3 inch height off of the current concrete base. Is that even allowed by code?

A second question is if I can avoid digging out this massive footing (which otherwise appears perfect) and drill some holes with rebar and pour another 2 inches of concrete on top of it? This would also then allow me to put one of those CPS6 standoffs and the RPBZ around it then.

Again, if not code compliant or just so far off the normal - digging it all out may be the answer then.

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