Deck pilings

[supton]

Decided today that it was time to dig into this mess. Deck sticks off the house 12' and is 16' long. It uses four pilings on the 16' side. One corner rises in the winter, and too bad, the piling doing the pushing is not on the corner, it is one piling in. The corner that lifts snapped the piling under it, about 18 inches down.

I started digging today, and gap in broken piling is more than an inch. I'm guessing I need to pull both pilings out, level the deck, and then I can put in new sonotubes? I'm a little murky on this, trying to tackle this on my own but I suspect I really need a pro to do this.

 

[supton]

Just measured it. Using a two foot level, I needed 1.25 inches to make the level, err level. That means I need to drop the deck 7.5 inches in that corner. I'm not sure if it would drop that much, the boards would fight me, no?

 

[IndyIan]

I guess the proper solution is to jack it up, cut out the pilings, put 4' deep sono tube with concrete and the proper anchor imbedded where each piling was, level the deck, then cut and install posts to length.
Just check how well the deck is attached to the house before you start working under it and jacking. Pilings says to me that there may be other issues.

 

[supton]

I can't win. Found another broken piling.

 

[JHZR2]

7.5? I thought the gap was an inch and then you needed 1.25" to level. Maybe Im just not comprehending.

At the mountain home, the deck is over the septic leach field mound. As a result, the pilings are not set in concrete, just large concrete blocks.

Seems that this may be a good option for you, let things naturally heave where they need to, and then let the others lift and not be excessively stressed. You know now which have issues and which dont.

Unless there is a systemmatic issue, like these arent all below the frost line... So if they were put in proper, this would not happen.

Id be careful with the lag bolts connecting to the home, they may be well stressed.

 

[supton]

I suspect it pulled the piling up, until it snapped. On the snapped one I've only dug down two feet, and the remnant is only starting to loosen. I've hit 30 inches on the lifting piling, and it's still solid. These pilings are at least three feet, and might be the proper four.

I like the idea of setting the deck on blocks, but I'm not sure why that isn't done more of the time.

 

[Donald]

I would suggest doing it with concrete in sono-tubes to below frost line. How far down do the current pilings go?

If you do it with blocks, yes easy now, but when you go to sell, it will be noticed and one more thing to deal with then.

If you need to jack the deck inches, I would do an inch or two at a time. Let the deck settle for a day or two and continue.

 

[supton]

My arms are giving out now, so not sure i will find out this weekend. But they are at least three foot long. I will have to find out what the locals use for frost line.

Interestingly enough, I may have found my water line, 30 inches down and two inches from one of the pilings.

 

[rfeir]

If the water line does not freeze it suggests the frost line is about 2 feet or so. I would go down 4 feet myself using 10" tubes.

 

[LargeCarManX2]

Idaho freeze depth is above 42 inches, we dig water and other depths always at least 42 inches to avoid freezing. So 4 foot back East sound reasonable for the final depth of a concrete base depth. Interesting your water line did not freeze at 30 inches?

 

[JHZR2]

Originally Posted By: Donald


If you do it with blocks, yes easy now, but when you go to sell, it will be noticed and one more thing to deal with then.



There must be a work around or waiver. In some places one can't do the tubes for various reasons.

Our deck has been hanging on for nearly 30 years now, on blocks.

 

[supton]

Yeah, I'm clueless. Maybe it's an old water line, or it is something else? There is a run to a spigot, but I don't see why it would run near there. The same for the electric run to the pump. (Electric runs from the closest corner in the basement to the well, the actual water into house the farthest corner, beats me why.) there is a French drain someplace, but that I thought was four inch white PVC, this is two inch black stuff. Maybe it is the drain for the side of the house?

Tomorrow I will dig some more. But if these are the proper four deep pilings, what should I do? Go six? Should I hope they are only three, and that one more foot will fix?

One odd thing is that the metal boxes used to hold the 4x4 to the piling are unscathed. No stretching. Makes me wonder if the piling was poorly poured. These appear to be clean breaks, no crumbling, but no rebar either. Hmm, one thought comes to mind, maybe they sheared... The broken pieces do not line up. Could be the deck angling as it went up, though. I'm digging through clay after the two foot mark, and it's getting to be rough going.

 

[Clevy]

Don't bother digging all that up. You can buy a mechanical adjuster that fastens to the post and you just use a crescent wrench to adjust it up and down with the seasons.
There is a collar that fastens to the top of the post and a metal plate that fastens to the deck. There is a threaded rod in between. The threaded rod adjusts in the collar and you basically screw the deck up and down.
Home Depot has them for sure.
The whole assembly might cost 20 bucks. Buy one for every post and never have a heave issue again.

 

[Clevy]

Originally Posted By: supton
Yeah, I'm clueless. Maybe it's an old water line, or it is something else? There is a run to a spigot, but I don't see why it would run near there. The same for the electric run to the pump. (Electric runs from the closest corner in the basement to the well, the actual water into house the farthest corner, beats me why.) there is a French drain someplace, but that I thought was four inch white PVC, this is two inch black stuff. Maybe it is the drain for the side of the house?

Tomorrow I will dig some more. But if these are the proper four deep pilings, what should I do? Go six? Should I hope they are only three, and that one more foot will fix?

One odd thing is that the metal boxes used to hold the 4x4 to the piling are unscathed. No stretching. Makes me wonder if the piling was poorly poured. These appear to be clean breaks, no crumbling, but no rebar either. Hmm, one thought comes to mind, maybe they sheared... The broken pieces do not line up. Could be the deck angling as it went up, though. I'm digging through clay after the two foot mark, and it's getting to be rough going.


We never put rebar in our pyles. Our frost line is 60 inches here. We pour to 72 so the pyles won't heave.
Find out what your frost line is and add a foot. That will prevent any heave ever again.
Or spend 20 bucks a post and just adjust the heave out every year.
Remember. You want the deck to slope somewhat to drain rain away.
For every foot in deck length you want an eighth slope.
So 8 foot deck would be an inch slope.

 

[supton]

Not to be rude Clevy but I think you misread. Two out of four of the concrete posts are snapped in half, and the deck is being held up by just two posts right now.

I overheard the contractor at my church yesterday talking about how little work he had this summer, maybe I will ask him. This digging is getting old.

 

[rjundi]

Typically in NH the frost line is 42"-48" deep and your pilings should go that deep. It may explain the split.

Call your local building inspector with the question. You are not required to take any permit(if concerned) as this is a repair.

 

[supton]

Found a photo. I have yet to figure out why I can't put photos here, I'm guessing it's our photo server/whatever.

Wasn't planning on bothering the local inspector. We asked about our a permit when redoing the roof, and was told we didn't need one, since we were sticking with shingle. Only if we were going to metal. I attempted a search on frost line, and most results indicated 48" for NH. Except Hanover, which indicated 5'. Hanover isn't that far away.

I am starting to think it's the layer of clay, and some sort of shearing action. Maybe it needs to be dug out fully, not dug with an auger?

Edit: Oh, in the photo, ignore the piling that is falling over. It was there when we bought, and was not used for anything. Once I dug down it loosened up enough that I could move it--clearly set too short--and I am planning on removing. I just don't have a tow chain/strap to pull it out at the moment.

 

[supton]

Got waylaid by injury, but did a bit more digging today. Made it to 30" and it's slow going. Is tempting to put a 12" sonotube around the broken one and pour, using what is left of the 8" piling at the center. Even at 30" the pilings are pretty well secured.

I'm not sure what holds the deck up. It is three pieces of 2x8 going across, with what I think is 16 penny nails. Looks like 5 nails in the three 2x8's on the post that does the lifting (one board only has one nail in it). Surprised they did not pull out.

edit: is also tempting to fix just one piling, and leave it running the length on just two pilings (remove the inner two). Too long of a run, I know--but that means it should take the bow out in a couple of years.

 

[supton]

Bought a pair of support jacks, lifted the deck this weekend. I double checked, and decided to whack the 4x4 on the lifting piling by 6 inches. Should have gone with my gut and done the "cut multiple times" route, as I wound up only needing to drop it about 4" to make it level. I *think* what threw me off is that the deck railings are bowed. Or something lever'd and stuff didn't have to move as far... Beats me, all I know it's dropped about 4" and looks much better.

I forgot to loosen the one attached 4x4, so I must have pulled it slightly upward. It's pretty loose. Then again, I dug down about 40", so it is not a shock. I've decided to reuse the piling that moves: upon digging it appears that the entire post is done in clay. So, I think as the clay froze, it was getting "glued" to the post, and allowing the clay below that (as the frost spreads downward) something to lift against. So, if I backfill with crushed stone it should fix that. If not, well, next summer I'll redo. Again.

I still need to dig one piling out, and pour. Unfortunately there is a second piling next to it, and they poured concrete around it, so I will have to chisel away. I'm tempted to do nothing, as the deck hasn't had a (working) post there for years.

 

[supton]

Deck has had some time to settle, after dropping. Decided to look at it today, and while examining one corner, and admiring the lag bolts (not), I kicked that piling. yep... broken. For fun I decided to dig down and look at the last piling. It's supporting a bunch of weight, but it too is broken. All were broken 6 to 18 inches from the top.

So, five pilings, four broken. I'm starting to wonder if the one that I claim is moving is the only one not moving...

I think I'm going to buy a couple more jacks, and just use that to support the deck instead. Not sure if I want only support columns holding it up, but geez, for all the pilings to have broken?