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Engineering solution to post pulling

Engineering solution to post pulling

Engineering solution to post pulling

(OP)
Classic problem of fence post in concrete rotted out & snapped maybe 6-8" (150-200mm) below ground level so I'm guessing I've got over a foot (300mm) of post still in there.

The concrete is a continuous run along the length of the fence, not discrete foundations for each post, so options of digging out the entire concrete (which I've done before elsewhere when I was younger) or even just putting new posts in a few feet to either side are not very practical.

Likewise numerous of the tools/techniques/gadgets on the various DIY websites etc aren't very practical for this situation. Plus as most of the fence is still up, there's a tree nearby, we'are in town and it's dry I don't like the idea of trying to burn it out.

We're in the desert and there's been no real rain for months so the wood below grade is probably pretty dry & not swollen too much.

I'm hoping - probably in vain - that I can put a couple of eye bolts down in the top of it and pull it out with some 'rope' and a 6' steel pole levered on a 12" tall piece of wood. Sadly the biggest eye bolts I could find at the store had probably less than 2" of thread lengh so I suspect will pull out before moving the post.

I can probably find some larger lag bolts/screws at a different DIY place but I'm still concerned that with the wood being rotten I may not get much grip.

I can obviously try drilling away some of the wood near a couple of edges but with the Drill I have I'm not sure I'll get down far enough to make much difference.

So before I waste a lot of time or buy a much beefier drill than I'll usually need I'm open to suggestions for a more elegant engineering solution.

It's OK if the solution is a bit half baked, this is a sows ear silk purse situation as the entire fence is a bit sorry but I don't have the time/money to do that right now.

I appreciate any help, if this is too much in the "DIY" category feel free to can it forum admin. I plan on doing the work Friday morning (6/27/14) so suggestions before then are most appreciated.

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What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?

RE: Engineering solution to post pulling

I've hogged out posts in concrete with a digging bar and shop vac, and grouted in a new metal post in the old location using the old concrete as the main post foundation. I had thought I'd need to use an auger to get the stub of the post out, but with rotted wood (I'm in a desert too), the digging bar was enough to break up the old redwood.

RE: Engineering solution to post pulling

I've had success with a sledge hammer and pair of vice grips. Hit the high parts straight down until the wood splits (usually splits in 2-3 solid wacks). Grab the high point with the vice grips and pull the split part out. That leaves a void that you can hit the surrounding wood towards. In a few minutes the wood will have completely collapsed into the hole in small long pieces that you can pull out.

Once I get the wood out, I cement an oversized galvanized sleeve into the hole flush with the surface and plumb (if I want to use a 1-3/4 OD post, then I make the sleeve 1-7/8 ID). Then you can either just use a metal fence post strapped to the fence and slid into the sleeve, or (if the first option raises aesthetic issues) you can drill a hole in your new wooden fence post about the size of the ID of the sleeve and epoxy a metal stub into the post and slide the stub into the sleeve. That makes replacing the post the next time pretty trivial.

David Simpson, PE
MuleShoe Engineering

Law is the common force organized to act as an obstacle of injustice Frédéric Bastiat

RE: Engineering solution to post pulling

Hire a big rotary breaker - something like a TE-76 or TE-80 - with a 1.5" or 2" rotary bit plus a chisel bit. Drill out as much wood as you can using the rotary bit. I know it's designed for masonry but they're not real fussy. Split out whatever is left using the chisel bit with the rotation stopped. Should only take an hour or so.

RE: Engineering solution to post pulling

I'll second the digging bar with a vacuum (or vice grips to pull bigger pieces) idea. A six foot, 20 lb., steel bar with a point on one end and a chisel blade on the other can break concrete or tree roots. It is a powerful tool and will make short work of your post remnants. And it only cost about $25.

If the wood is pretty dry then dropping some lit charcoal in the hole would take less effort and get rid of the wood over-night. You cannot get a flare-up in a hole.

RE: Engineering solution to post pulling

to quote Jaime from Mythbusters...

"When all else fails... C4."

RE: Engineering solution to post pulling

Thanks for dropping in, KENAT.
Yours
Bill

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Engineering solution to post pulling

My thoughts mirrored Compositepro, burn the wood out. With a cavity where the wood used to be, the concrete might break up a little easier if it needs to come out. A digging iron or other implement might be useful, or, if legal some rather large firecrackers, M80 or 1/4 stick come to mind.

RE: Engineering solution to post pulling

Is drilling it out of the question? use an electricians long deep timber drill and bore that wood a few times, soon it will be weak and you can pull it out. I would say drill new the four corners and on a few inches in the center, add a long eye-bolt, wank away. probably with a mechanical winch. Or keep drilling and soon it will mostly be small strips. This would be my route.

RE: Engineering solution to post pulling

Attempts to pull will be a failure- don't waste your time.

Many good suggestions already. I personally would use an auger bit (ship-builder's bit as some call them- like the ones once used with brace and bit sets) on a powerful corded drill. Hog out the centre by boring as many holes as you can get purchase to drill, then use the 6' crowbar to pry the wood into the voids made by the holes. If you have the room to work, grout a post base into the hole left by the rotted post timber. This will get rid of the source of the problem which is the soil-wood contact.

RE: Engineering solution to post pulling

IF you have a long drill bit and a solid, sturdy rod of equal or slightly larger diameter, drill a single, vertical hole until you hit the concrete base. Fill hole about half way with water, oil, grease, whatever. Then put rod in hole and sledge hammer it until rod meets fluid. Then, sledge the hell out of it. Pull the rod (this needs pre-planning, of course), refill fluid and repeat. Hopefully, the fluid gets mostly under the post and the pressure impulses press the post out. Or, it breaks thru the bottom concrete, in which case you're screwed and you'll need a Plan B.

Good luck,
Latexman

Technically, the glass is always full - 1/2 air and 1/2 water.

RE: Engineering solution to post pulling

Kenat,
If you have not already broken the post up in the hole. Find the longest lag screw you can at the local hardware store, at least 6" of screw thread and at least 1/2" dia., take a drill of tapping size for that screw and drill down just off center for the length of the screw.
Obtain and install an anchor ring obtainable at Grainger's and some hardware stores, search anchor rings. Then drill another hole at the ring spacing. install the lug screws with an extension bar on a ratchet wrench or a rotary impact wrench.
You now have an attachment that should take at least 2 to 3 tons of upward pull if the wood is not totally rotted out, If it is we do not need this conversation , scoop it out with a spoon.
Now you can go back to your 6'-0" steel bar, and block of wood, however I would suggest borrowing a hydraulic jack to lever up with instead of using Armstrong power. I have done this job myself using an engine hoist over the hole with the arm set at the 2 ton setting.
Good luck.
B.E.

You are judged not by what you know, but by what you can do.

RE: Engineering solution to post pulling

My comment that pulling will be a failure is on the assumption that if the post is rotten through at the wood to concrete transition, it's even more rotten IN the concrete. In your neck of the woods, that may not be true and the suggestion about the lag screws might be worth a try.

RE: Engineering solution to post pulling

(OP)
Well thanks everyone.

First job Friday is to clear all the junk out of the hole that fell into it when I removed the post. Second job is to do a more thorough job of assessing just how degraded the wood in the hole is and go from there. I did check out a couple of local tool rental places websites to get some idea of the cost of renting a beefier drill but they didn't make it easy so I'll give them a call Friday if my initial attempts don't work.

Kudos to Latexman for the most engineered solution (there is a tool that kind of does that for you but it relies on being pushed down in the soil next to the post or individual concrete footing so I don't think would work for me).

Right now if I had to bet my money would be on the 'beat it into little pieces' approach espoused by 77JQX, Zdas & others being what ends up getting it done but I'm gonna consider other options in more detail once I'm actually there.

Posting guidelines FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm? (probably not aimed specifically at you)
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?

RE: Engineering solution to post pulling

Yep, my way only works if everything is pretty much bubble tight and close tolerances, except the post/concrete interfaces. I'd say the probability of that is low given general wear, tear, and decay over the years.

Good luck,
Latexman

Technically, the glass is always full - 1/2 air and 1/2 water.

RE: Engineering solution to post pulling

Kenat,
If you use Latexman's method Use a Looong handled sledge and stay well back from the edge of the hole sadeyes
B.E.

You are judged not by what you know, but by what you can do.

RE: Engineering solution to post pulling

Kenat:

If you can auger down into the wood, an M-88 can pull it out, and probably the rest of the strip footing too! 2thumbsup I think you can rent one from your local National Guard unit.

Mike McCann
MMC Engineering

RE: Engineering solution to post pulling

(OP)
cbl, I've used the metpost products before but:

A. I didn't see them at my local hardware store in desertville california (yes I probably could find them online somewhere).
B. The post broke quite deep down so would be challenging to 'flatten out' and may not have enough depth to take the tine.
C. I had a bit of trouble with the products I did use with them 'wandering' on occasion. I'd guess this product would be better as it aligns on the concrete but...

Posting guidelines FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm? (probably not aimed specifically at you)
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?

RE: Engineering solution to post pulling

You could cut a 6"-8" length of post to make up the difference in height ... or ram concrete into the hole.

Is there room to get a sawzall down into the hole?

RE: Engineering solution to post pulling

Just because there was a post there doesn't mean that there always has to be one there. It sounds as if the fence is getting rebuilt in the vicinity of the rotted post, so a slighly different post location probably won't be noticable. Probably don't need to be too concerned with seismic load on a fence but you might need to assess the wind load.

Fill the old hole with masonry plug of some variety and set a Simpson bracket of some other sort in a new, nearby hole.

http://www.strongtie.com/products/connectors/EPB44...

RE: Engineering solution to post pulling

DVD,
From Kens original post "The concrete is a continuous run along the length of the fence, not discrete foundations for each post,"

B.E.

You are judged not by what you know, but by what you can do.

RE: Engineering solution to post pulling

My thought was that a hole would be drilled in the existing continuous footing and an anchor epoxied in place. There are various Simpson products available which may prove suitable, or unsuitable - caveat emptor.

RE: Engineering solution to post pulling

(OP)
Well, I pretty much wasted everyone's time sorry. After cleaining it out, drilling a couple exploratory holes and pocking around with a pry bar I decided to try one of my eye bolts just to see.

Screwed it in thinking it was spinning in rotten wood, pulled on the eye bolt to see if it would even hold before setting up a lever and it came out in my hand. Piece of cake!

Now for trying to get the new post in...

Posting guidelines FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm? (probably not aimed specifically at you)
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?

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