Sinking deck post

Jstas

I vonder vhat eet ess zinking about?

So, looking for some experienced advice here.

The pool deck is quite old. How old, I dunno. The pool has been there since some time between 1965 and 1972. I don't know when the deck was put on but it is old enough that the structure is made from the older "bad", "never gonna rot" pressure treating process.

I know this because the posts that hold the whole thing up are buried in the soil and there's not much wrong with them at all.

Except, I have 3 of them that are leaning. It's a 4 degree lean away from the pool so it's pretty substantial. I thought they were just warped. Turns out, though, they're actually sinking and since the deck is anchored to the galvanized steel pool structure, they are pulling in at the bottom towards the pool.

Additionally, the deck is sloped away from the pool where the 3 sinking posts are and the other areas are relatively level with less than half a degree off bubble. Same with the other posts. The only one that's more than half a degree is one adjacent to the 3 leaning and it is leaning a bit towards the sinking posts.

So these posts are dragging everything down with them.

I did some "exploring" with a shovel and I'm pretty sure that they "footing" the posts are on are just a couple of bricks that were put at the bottom of the holes.

So last weekend, I decided to pull out the air over hydraulic 20 ton bottle jack I have see if I could get the deck to rise up to level. I was successful in this endeavor. The post didn't straighten out but that's because of where I had the jack positioned.

What I have to do is clear now. I need to dig out the base of the posts, straighten them and then fix the footings.

I was wondering if anyone had any experience with this and what they did to remedy it.


I'm thinking I need to level the deck at each post with the bottle jack, cut the post bottom off at ground level, dig down to remove the old garbage footing and post and then put a post base bracket on and bolt it to the concrete footing. Or is that a massive amount of overkill?

VR3

Im on board with protruded concrete with base plates. It is the way

Jstas

Protruded concrete? That's a new one on me. What is that?

VR3

Ie, you dig down and do a sonotube where the concrete protrudes several inches above ground, install your base plate and roll

Jstas

Ohhhhhhhh....it's in reference to the installation. I thought it was some fancy new kind of cement or something!

VR3

You can try that new fangled foam all the rage on tiktok

skipshot12

What vr3 said.
Once & done.

Jstas

That new fangled foam says right on the package that it is not suitable for structural use. It doesn't support weight, it's only intended for mailboxes or fence posts and stuff.

Believe me, I wish it was weight stable, would make things WAY easier.

mrbigbluelight

No to foam.
VR3's the way to go.

How deep is the frost line in your area ?

Jstas

3 frickin' feet

Part of the reason these posts are sinking is because they are sliding underground. The "footing" (i.e.: two bricks) is only about a foot and a half down. So the freeze/thaw cycle with pressure from the deck and pool wall is shoving it all around.

An 8" footing is going to need a 12 inch hole with a base poured at the bottom and rebar jammed through it into the dirt to keep it all from shifting around. Then the 8" sonotube and then fill it with concrete and jam a bolt in the top so there's something to bolt the base plate to.

Would be easier if I didn't have to work around the existing post but, hey, what did I honestly expect with the way everything else here goes?

If it was done right to begin with, I wouldn't have to screw around with this.

Jstas

The other thing I'm thinking now is that unless I completely disassemble this and pull the post out completely, I will have to stretch a come-a-long across the pool to the opposite side of the deck and use it pull the pool wall vertical again and straighten the post out.

I only say this 'cause, I'm stronger than the average bear but I ain't shifting a 45 foot by 25 foot deck and hold it there while I brace it so it stays true levels of strong.

If any of you are, I'll gladly buy you pizza and beer and give you a free pool pass if you want to come on over and show this deck who's boss.

VR3

F1nut

https://www.midwestpermacolumn.com/product-category/foundation-bases/pre-cast-concrete-foundation-pads

msg

Curious, what's your soil like, John? Clay? Sandy? Rocky?

audioluvr

I jacked mine back up and releveled then using 2x6's built an 18" square form and filled it with concrete. Once the concrete cured I removed the jack. Haven't had any problems since and that was 20 years ago

msg

Is the post bearing on the concrete or just encased by it?

mrbigbluelight

Just a quick side note: unstead of a come-a-long I might suggest using a chainfall instead.

Just a preference on my part but I actually detest come-a-longs with a passion.

Also, just wondering, but would it be possible to just abandon the established posts and pour new bases/posts to the right or left ? You've probably already considered that but just wondering. 🤔

Jstas

VR3 wrote: »

That's pretty slick! Seems like I can't get them here before the middle of June, though.

mhardy6647

It is the middle of June already -- to a very good approximation!
15 - 7 = 8
8/366 => 2.19% away from mid-June.

Jstas

F1nut wrote: »

https://www.midwestpermacolumn.com/product-category/foundation-bases/pre-cast-concrete-foundation-pads

That's actually a good idea but...shipping on them sucks. $8 bucks each, $154 shipping. Sonotubes and concrete bags for all the columns cost $225 and I'll still have to dig an awkward hole.

But, I found this on their site too:

https://www.midwestpermacolumn.com/product/fp12

Which doesn't need any concrete at all. I have to read up on them, see if they will allow anchoring so they don't shift around.

But, that composite pad might work better for this situation but I gotta look at stuff. I can't just put the new pad down and go because it needs to be below the frost line which is the cause of the problem we have. So I still have to dig a hole.

But if I can use the footing pad and bury a 6x6, I might be able to cut the 4x4 off at the framing, put a new 6x6 hole and use a galvanized post cap to tie it into the existing framing.

Also, found them on Amazon from a reseller
https://www.amazon.com/FootingPad-12-Diameter-4-Pack/dp/B08K1PY14J/ref=sr_1_4?crid=1JAAYMY60SGV7&dib=eyJ2IjoiMSJ9.HLcAFWBpsFDdVkytKm0NOn6uW-CG26J1Os_Q4rkudSGV-43MORTmBJlQ6lzI7kCLer8RDbVrM5Ii1Xb5XXNw8O9CAs03ubr_XPhBxfpZ1mg5gE9C4IHYsn_JHA8smF6SZz542qVin5lWVUEp4DXQA3ljDh7vAgyouAEde3-AZo8_WMUdKvHZAJQfhqsYddBt-for2ZLlZ4fKbD5t0IQd6MRCxWUL8mWoB6JDYG4NNZFF0Rqss5mpLiTFU6PBxqKQC11FjVGHAWKlJ7jPWs0q8ay62pSNADlYNR5VkRIr6BA.3B2eicHQmh4orNtk97u9qKNbFEfCBsrbXjJYLpMP868&dib_tag=se&keywords=composite+foundation+pad&qid=1717763836&sprefix=composite+foundatio,aps,102&sr=8-4

Jstas

msg wrote: »

Curious, what's your soil like, John? Clay? Sandy? Rocky?

Glacial till.

So sandy/loamy with clay/marl underneath. Also, water table is high. So part of the reason these posts are sinking is because of no lateral stability. Additionally, high weight on a small foot print.

Which all sucks because digging down 4 feet, you start hitting the water table. The frost line is around 3 feet. So if I only have to dig down like 40 inches to set a footing pad, that'd be better.

Jstas

audioluvr wrote: »

I jacked mine back up and releveled then using 2x6's built an 18" square form and filled it with concrete. Once the concrete cured I removed the jack. Haven't had any problems since and that was 20 years ago

I can't do that. The ground tends to get saturated and something sitting on top of the soil will just shift around like warm toast on peanut butter. Plus...frost heaves.

I think that the reason I have such deflection in this one area is because the pool freezes in the winter and the expanding ice pushes on the top of the pool which pushes on the deck. That pushing over the years because of the unstable footing is what's caused this deflection and subsequent sinking. The 3 posts that need replacement are at the center of the pool rectangle. The opposite side doesn't seem to be affect as much because there's a ton of tree roots there and they don't let anything shift. The side that is affected is just lawn and that part of the lawn is the lowest part of the property and routinely has standing water in heavy rains.

Jstas

mrbigbluelight wrote: »

Just a quick side note: unstead of a come-a-long I might suggest using a chainfall instead.

Just a preference on my part but I actually detest come-a-longs with a passion.

Also, just wondering, but would it be possible to just abandon the established posts and pour new bases/posts to the right or left ? You've probably already considered that but just wondering. 🤔

Chainfall? You know that's a hoist, right? It won't put lateral tension on anything and I'd have to rig it up in a manner that would make using it an exercise on my profanity vocabulary. Besides that, the only one I have is on my gantry crane and I'm not going to screw around with a 4 ton hoist that weighs 80 pounds and it's greasy chain just to pull a 4x4 post a few inches back into plumb. Especially when I have timber rigging that weighs a fraction of that and lets me use a 10 pound come-a-long to do the same thing on up to 12,000 pounds.

Block and tackle would be better but I don't have a block and tackle set that I would trust to handle it without snapping ropes.

As far as abandoning posts, no, The pool walls have a concrete apron around the base to keep them from getting pushed out by the water at the bottom. There's outriggers on the pool to that are also in concrete footings. Where the deck posts are is in between those outriggers so I can't move the posts without have to significantly rebuild the deck structure. Hell, I can't even surgically extract the posts to replace them because everything from the framing to the decking to the railing is attached to them. They are literally 12 foot 4x4's and they go from about a foot below grade to the top of the railings.

I'll have to take pictures later today when I can make the trek to the other side of the property with a camera.

Jstas

mhardy6647 wrote: »

It is the middle of June already -- to a very good approximation!
15 - 7 = 8
8/366 => 2.19% away from mid-June.

They gave me an arrival date of June 22nd and coming by freight which is absurd since the only place I could find them "in stock" was selling them at $26 for a 4 pack.

mrbigbluelight

You can definetly use a chain fall laterally.
Done it many times on heavy loads, no problems.
Come-a-longs suck. Period.

invalid

Lot easier with a chain fall

Jstas

Yeah, I don't have a chainfall I can use easily and I'm not going to go buy another one. I'd sooner pull the 12K pound winch off it's current location, strap it to the lawn tractor and deadman it to a tree before I drop a couple hundred on a chainfall that's manageable. I mean, there is a large hole in between the two sides full of mucky water and I'd have to be standing in it to use a chainfall and this job is **** enough, I don't need to exacerbate it by intentionally standing in mucky water that smells like the Swamp Thing's aftershave.

So I'm gonna jack it up with my air over hydraulic 20T bottle jack, run a towing strap around one end and a tree anchor around the other and pull it in 4 inches with my 4,000 pound come-a-long and smile as I'm doing it because I know how much y'all hate it.

Jstas

OK, pitchur time!

So this is the deck with the 3 bothersome posts marked.



They are leaning towards the direction of the camera. The pool is 4 feet deep and it's a 4 inch separation from the top sides so that's a 1:12 ratio for the pitch. If I take my 2 foot level and hold it up against a post and then move it until the bubble is centered, it's a little under a 2" gap at the widest. Significant lean.

The posts are all framed out in the same way as this



What I'm thinking is if I cut the 4x4 post off at the bottom where the red line is in this picture...



I can dig a 16 inch wide by 40 inch deep hole to put that composite footing in with some gravel at the bottom. Drop a 6x6 in that gets me to where the level deck is and then use some post/beam framing plates to connect the 6x6 to the deck.

They say that the compacted fill dirt in the hole will keep the post from shifting but I think I might get a couple stainless steel lag bolts for each one and connect the composite footing to the post. I think I will punch half inch holes in the edges and bend some rebar to "staple" the footing in place too.

A 16 inch footing would spread out a bunch of weight and is way less likely to sink. Pinning everything together will keep it from shifting too so it's not relying totally on the soft soil that's already failed to keep things in place.

The only downside is that the stairs will be a pain and the 6x6 will have to be offset to compensate but that's not that big of a deal. There's only 8 feet between posts anyway.



But the stringers are just face screwed in and they're not even done right. No wonder they are falling apart. This is most definitely Captain Halfassery so I'll have to fix it with a proper header plate and properly cut stringers.



This gives me a clue as to how long the deck has been here, though. Captain Halfass did not build the deck but he did "refinish it". When he did what he did, the posts were already leaning and instead of fixing the lean, he just blocked things out to make it "straight" as you can see in these pictures.






So the deck itself is probably from the 70's at the earliest. It might have been rebuilt in the 80's. All I know is that much of the wood has that old, copper patina tinge to it that you don't see anymore 'cause even though that stuff works like gang busters, it's bad and you can't use it anymore. Hasn't been available since the late 90's and all the manufacturers voluntarily pulled all stock for residential use in like 2003. So it's the old type of pressure treated. But the deck surface, railings and stairs are probably from 2002-2003 or so which is when Captain Halfass started making his significant "improvements" to the property including halfassing the enclosed porch that cost $22K to fix, halfassing the massive wrap around porch roof that's going to require a miracle to get fixed and the garage roof that replaced a lally column with half a box of deck screws and galvanized steel plates.

Fun times. Fun times.

And all this started out because the pool liner is leaking and needs to be replaced.

Everything this guy touched is like a rotten onion. Looks ok on the outside but as you start peeling apart layers, each successive layer is even more festering and rotten than the next.

pitdogg2

No disrespect John but that deck looks like a splinter factory

Jstas

Hence the reason I have to resurface it.

But the path you see in the picture is not level and with the framing being pulled on by the posts, I can't put a new surface down until I fix that lean or I'll be redoing the resurfacing again in a couple years.

I also wasn't sure why all the boards there seemed to be pulling their fasteners out sideways.

Now I know.

Also, Captain Halfass did not pay attention to the crown when he was **** and nailing deck boards down. So the ones that have the crown facing up are bowed and pulling their fasteners and the ones with the crown upside down have multiple rusted fasteners because they cupped, trapped water froze and separate the grain structure and all the screws and nails keep corroding out because of it.