Replacing a wood post in a slab.....

[wrench409]

The post in question is a treated wood 4x4 placed in a concrete slab in the 1970's. The original owner used that post as a gate post. His gate was a simple wooden swing gate that weighed little. Along comes wrench409 and I decide to revamp it. I built a metal frame of 1 1/4" square tubing and hung it from the same wood post 4 years ago. I used cedar fence pickits to cover it on both sides.

Now the sag has become unmanagable. I knew it would eventually. I want to remove the wood post - it's nominal is 3.5" x 3.5". Remember it's in a slab, not a concrete in dirt type of fence post. How can I remove all of the wood in that square hole and place a square steel tubing post in it WITHOUT cutting into the slab? Is there a product that will rot all the wood pretty fast?

I have access to the steel post sized correctly. And how to secure it in that old square hole? Epoxy? ????

 

[Stuart in MN]

I don't suppose there's a way to tell if the whole post is set in concrete, or if it's just sticking down through a slab into the dirt below. If it's just set in dirt, you may be able to pull it out - wrap a chain around the post and lift it out with a bumper jack. If the whole thing is set in concrete, I suppose you could cut it off, then drill and/or chisel out the wood below grade.

 

[wrench409]

True. The slab is 12" thick. I am hoping for some product that can get rid of the wood without all that chiseling. Start on a Thursday evening and finish it by Sunday kind of plan.

 

[gregtwojeeps]

Use this to chew the postout, it won't take that long while using a shop vac to clean out. Then, set your steel post and pour epoxy around it. JMO

 

[38 Dodge Coupe]

I suppose it's possible to remove the 4x4 from the concrete, but I am not aware of any specific tool to accomplish that. I suspect that not only is there a concrete slab that is around it, I suspect the hole was dug at least 24"deep as well and filled with concrete too. Normally you would just cut around the post and jack hammer the concrete out.

However,I guess you could cut the post flush and long spade bit and starting drilling it out. Once enough material had been removed you could take a spud bar and finish breaking it out, similar to drilling out a bolt that was broken off. Are you planning to put the new post inside the old hole?

I wish you well and I will be interested to see what other methods may be out there.

 

[matt_i]

I think you are making a mistake thinking the steel post will automatically set in the same hole and function perfectly.

Better solution would be to saw and breakout a square piece, lets just say 12" square for arguments sake. Excavate, drill the bottom of the new post for some rebars to cross thru at 90 degree angles, pour new concrete to solidify everything.

A big potential dilemma is this. Suppose you could magically make the wood disappear. Now suppose you are setting the steel tube and it gets stuck some distance up from the bottom. Then you truly have a problem, especially if there is some weldment already on the tube which has to be set to a specific elevation.

 

[Dirtydan69]

You could verify if there is deep concrete holding the post. You'll need a section of chain with a hook at the end and a high lift jack. Called a farm jack sometimes. It's similar to an old bumper jack. Wrap the chain around the post and itself several times. Leave a length of chain and hook it to itself leaving a loop at the end. Place the jack next to the post maybe on top of a 2x6 or bigger. Hook the loop onto the jack and use tha jack. Slowly as they can kick back. If that post is just in the ground under the slab it should come out. 4" of concrete will not hold it. If there is concrete holding the post in the hole it will most likely not move at all.

 

[Thumper68]

I would go with the cut/drill/chisel shouldn't take long at all.

Sometimes we tend to over think it and spend more time and energy doing it the "easy" way, when simple gets the job done.

 

[langss]

I have re-worked several fence post that were set in concrete that rotted off. Its a pain to get all the wood out, but it can be done. Since mine were rotted the wood came out pretty easy, but if you could find the bit in the picture that would work as well. As was previously suggested, I just used a shop vac to clean up. Good luck.

 

[theoldwizard1]

Big drill ("Hole Hawg"), big drill bit. I think an auger style bit would be better than a spade bit.

 

[motofool33]

Big drill ("Hole Hawg"), big drill bit. I think and auger style bit would be better than a spade bit.

i would definitly go with an auger bit versus spade

 

[gregtwojeeps]

I respectfully disagree on the auger vs. flat bit. The hole at the bottom of the post could be solid concrete. The auger bit will pull in to the wood fast and keep pulling and may hit the concrete , plus there is the potential the auger bit binding up and the jammed up drill smashing a person's hand against the concrete edge. A lot of wood chips will have to be vacuumed anyway making it a stop and go project anyway. Just makes more work un- hanging an auger bit screw ...every time its vacuuming time. JMO

 

[rlitman]

I agree with gregtwojeeps regarding the paddle bit.

Though I would not cut the post at ground level first.

I'd cut it at knee level. Then drill a horizontal hole or two through the middle of a side just above the ground. Next, saw a cut in from the side to the hole, and then split the post down to this hole.

Now you have a handle. Now drill out half the underground post, and use the handle to pull the other half once it's loosened.

 

[T_R]

Burn it out, no tools needed, maybe a bit of gas.

 

[wrench409]

All great advice. I will print it all out and use as much as I can.

It's a Spring or early Summer project as it's pretty cool right now.

Thanks everyone!

 

[Michigan Mike]

Just a quick question. If the gate is sagging now what is going to keep it from sagging with a metal post. If you don't have something heavy and deep enough to hold the bottom of the post it won't matter if it is wood or steel.

 

[mrpizza]

I second the burn it out. Soak it in some kerosene for a day then light it up. Then use the spade bit to get the remnants out, and chisel the wood in the corners.

 

[BFBOB]

I second (or third) the jack idea. Or shop crane, hydraulic jack with a cleat on the post to push against, comealong on tripod, front loader on a tractor, some such. Quick and easy to try (assuming you have a suitable puller/pusher on hand) If it works, great. If not, you've lost maybe an hour.

 

[Syberia]

Fun method is to cut it flush, drill a bunch of holes, soak in diesel or used motor oil, and light on fire.

 

[wrench409]

Just a quick question. If the gate is sagging now what is going to keep it from sagging with a metal post. If you don't have something heavy and deep enough to hold the bottom of the post it won't matter if it is wood or steel.

The concrete pad it's embedded into is 12" thick (at least). The wood post is warping. The part of the post that is at the concrete is straight. I am hoping to avoid the cutting of the concrete pad. It all has to do with what I find when the wood is out of the hole.

 

[soj]

Is the post leaning toward where the gate normally is? In other words, is the gate normally closed, and the post is leaning in that direction? If so, and if the gate is unsupported when closed, just install a support under the gate. If it took 4 years for the sag to become unmanageable, the post should be able to handle the weight in other directions when the gate is open temporarily . All this is assuming the gate is normally closed and occasionally open. OTOH, if it is closed all night and open all day, then a gate support at open and closed positions should keep the post plum.

Either way, installing a gate support or two should be much easier than digging treated wood out of a 3 1/2" square hole of unknown depth.
jp

 

[RickP]

The concrete pad it's embedded into is 12" thick (at least). The wood post is warping. The part of the post that is at the concrete is straight. I am hoping to avoid the cutting of the concrete pad. It all has to do with what I find when the wood is out of the hole.

I hate to be the bearer of bad news... but you're probably going to need a lot more concrete than 12" under the slab. My gate weighs about the same as yours, and it has a 6 x 6 steel post, embedded in a footer poured with a full yard of concrete. It still sags a little, but it's manageable.

 

[wildstyle]

Put a guide wheel on the other end of the gate so that it is carrying the weight of the gate instead of the post?

 

[Shiftless]

Put a guide wheel on the other end of the gate so that it is carrying the weight of the gate instead of the post?

^^^^^ Best idea yet! ^^^^^.

Also... Your concrete walkway is 12 inches thick? That's about the same thickness as an interstate highway with 80,000 pound semis pounding it every day for decades.

 

[Leaflessshadetree]

Any way to support the top of the post, better if you can put some tension away from the gate.

 

[Shiftless]

Any way to support the top of the post, better if you can put some tension away from the gate.

Another great idea there from Leaflessshadetree

I have a heavy wooden walkway gate 4 feet wide hinged onto a 6x6 wooden post sunk in concrete. To prevent sag, I put a 4x6 cross piece 7 feet up between posts. I made it easily removeable in case I had to move something tall past the gate. 20 years later, the gate is still fine... no drag.
You might be able to use that idea.
How wide is that gate anyway?

 

[Michigan Mike]

One other option is to put a small block or angle on the post on the latch side of the gate. This will carry the weight of the gate when it is closed.

 

[Crusarius]

What about build a new support post and use expansion anchors to the existing slab? Vertical column with diagonal brace should do nicely.

Forgive me if the pic shows something I can't see it at work due to the firewall.

 

[PugetDude]

The post in question is a treated wood 4x4 placed in a concrete slab in the 1970's. The original owner used that post as a gate post. His gate was a simple wooden swing gate that weighed little. Along comes wrench409 and I decide to revamp it. I built a metal frame of 1 1/4" square tubing and hung it from the same wood post 4 years ago. I used cedar fence pickits to cover it on both sides.

Now the sag has become unmanagable. I knew it would eventually. I want to remove the wood post - it's nominal is 3.5" x 3.5". Remember it's in a slab, not a concrete in dirt type of fence post. How can I remove all of the wood in that square hole and place a square steel tubing post in it WITHOUT cutting into the slab? Is there a product that will rot all the wood pretty fast?

I have access to the steel post sized correctly. And how to secure it in that old square hole? Epoxy? ????

Pictures. We need pictures.

 

[wrench409]

The gate is 9 ft. wide.

I built a bracket today for a wheel to add to it. I did the bracing via concrete anchors when I took his old gate down. The fence posts he put in years ago were really warped all over the place when I rebuilt the fence - all were sunk directly into the slab from the gate post to the garage. I had to do some shimming to get a straight fence line. The post for the gate is just too old to deal with. I will call the old owner and ask him some questions about how deep the gate post is and if it extends deeper than the 12" thick slab. He's pretty old (88 when we bought the place), so I hope he remembers.

Sorry I don't have pictures. The wheel will be sufficient for now.

 

[wrench409]

Hit the garage today and finished the bracket mounting and outfitted a wheel at the end of the gate. Working good now.

The post can wait till summer....

Thanks everyone!

HAVE A SAFE AND HAPPY HOLIDAY!

 

[theoldwizard1]

Burn it out, no tools needed, maybe a bit of gas.

Very bad if it is PT wood. The smoke would contain some nasty chemicals.

 

[Hobbit]

Use to pull posts like that up with the 3pt hitch on a tractor using bolts & chains. I would assume there are some sort of anchor bolts in the post/slab that need to fail in order for it to break loose though.

 

[G McKay]

Use this to chew the postout, it won't take that long while using a shop vac to clean out. Then, set your steel post and pour epoxy around it. JMO

You can get them in a lot bigger sizes, too. Say 2".

 

[dreamingmuscle]

Screw a 2x4 to the side of the post slip a farm jack under the 2x4 and jack the post out. Concrete doesn't stick to wood to well. It should pop right out unless they drove some nails half way into in the post.


Glen

 

[TheEquineFencer]

When I need to "pop a post out of the ground" I use decking screws and attach a 2x4 or 2x6 to the side of the post, put a block of wood beside the post and take the tip of the fork for my tractor under the board screwed to the post and use the other block as a fulcrum and pop it out of the ground. Another option is to cut if off at the ground, drill it full of holes and set a few Match Light charcoal briquettes on top of the post and light them. Add a few as they burn down.

 

[Kaizen]

Hit the garage today and finished the bracket mounting and outfitted a wheel at the end of the gate. Working good now.

The post can wait till summer....

Thanks everyone!

HAVE A SAFE AND HAPPY HOLIDAY!

I had a similar one I had to remove that wiggled a little in winter. I waited till summer and it had swelled up like wood does so I had to do the drill and burn. absolutely sucked. figured if I got the middle out I could collapse it but man that wood held on so I had to put some acetylene on it.