4x4 sunk in cement, how to remove em ?

[waynekarnes]

bought a 10x16 foot tuff shed from my bro. moved it to my house ( doesn't come apart, moves same as moving a small house ) . put it in back yard. gate in front of rv pad and part of the fence had to come down.

 

unbolted the hinges holding the gate ( redwood fence and gate ). used a hand saw, cut the redwood 4x4 posts flush with the cement. shed and trailer fit between my house and fence separating my yard from neighbor's.

 

the remenants of the posts are roughly 18 to 24 inches in the ground. about 9 years ago, i had the driveway widened from 2 cars to 3 wide and an rv pad ( 15 x 25 ) added along side my garage.

 

the fence and gate were existing. to clear the new cement, the contractor used a skill saw, cut off the bottom of the fence boards, cemented around the 4x4 redwood posts. the cement is about 4 to 5 inches thick. so there is say 2 ft of post in the ground and another 4 to 5 inches of cement added to that.

 

i need to get those old posts out, so i can put my gate and fence back up. i bought an inch and a half wide, 16 inch long, hole boring bit ( not a hole saw ). i spent 2 hours drilling and vacuuming the sawdust out ( if i don't vacuum, the sawdust turns to powder and lubricates the bit to the point where it won't cut ).

 

i'm attempting to hollow out the post and maybe get the sides to pull away from the cement. after 2 hours, i'm about 3/4 of the way there. i can get an extension for the drill bit to get down deeper and modify a tube to get deeper in to get the saw dust out.

 

figure at this rate ... gonna take me 4 or 5 hours.

 

 

any one out there got a better idea ??? i can't burn em out ( city codes ). thought about renting an auger and fence post drill, but that's around 80 to 100 bucks for 4 hours. 4 hour min. 100 bucks to rent a cement saw as well.

 

 

any thoughts as to how to get em out ?? other than what i'm doing now ?

 

plus any advise on replacing em ... i figure, pour a little cement in the hole, too much and i won't be able to get the new post in as excessive cement won't be able to get out ( think a piston in a cylinder, trying to compress water ).

 

wooden shims around the sides of the new posts. can't have the post wobbling in the hole in the cement, as these post have to hold the gate and the fence. the gate is 9' 6" wide, two sections, split down the middle. made of redwood, fairly heavy.

 

suggestions ???

 

thanks, wayne

[Pop N Wood]

Every time I have done it I just used a hand held post hole digger and dug a new hole around the old. You only need to go about half way around. Can then rock the post side to side and get the post and all the concrete out. Would have helped had you not cut the old post flush first.

 

Originally I tried all kinds of way to do it with less work, but always ended up doing the above. I imagine a back hoe would be the best but I didn't exactly have one laying around.

 

Also remember concrete is brittle and cracks easily. Once you get the surrounding dirt out you can easily chip it away from the post with a sledge or digging bar.

 

Good times......

[CruxGNZ]

I guess your best bet is to dig around the concrete and wiggle it back and forth to get it out, like previously stated. If you still had some wood above the concrete, you could have drilled a hole through the wood, slid a chain through and pulled it right out of the ground with a cherry picker (engine hoist).

 

!M!

[Dan Juday]

If I read Wayne's post right, he doesn't want to bust out the concrete, it's part of his driveway now.

 

Burning would be a good idea but for those damn San Jose rules (glad I left).

 

I think you're stuck with the method you're using. But I seriously doubt you're going to get new 4x4's back in there without busting out the concrete. I'd replace them with steel "I" beams. No problem getting the new cement in the hole that way either. Then drill and lag screw to the redwood. With the steel you wouldn't have to go as deep in the ground to get the same strength as wood.

[waynekarnes]

hello,

 

Dan is correct. the posts are part of the driveway to the rv pad. they used to hold the gate and part of the fence in front of the rv pad.

 

i used a hand saw and cut em off flush to the cement. was the only way to get that 10x16 tuff shed in the back yard.

 

now i need to get the gate back in place.

 

if i could burn em out ... that's what i'd do. drill some holes, fill em with charcoal lighter fluid and light em off.

 

there are no posts to grab and wiggle, as they are flush with the concrete driveway.

 

so far i have drilled down the 16 inches that my bit reaches, still hitting wood. off to sears for an extension for the bit. it's one of those bits that looks like a slotted ( carded ) screw driver, used for boring holes. bit keeps drifting and i hit the cement, so the bit is more burning it's way through tahn cutting. need to hit it with the dremil . 10 bucks for the bit, think 15 for the extension.

 

right now, if i can't come up with a better plan, i t hink i am looking at 4 to 5 hours on each post ... there are only 2 of em. the third 4x4, i paid for redwood, contractor back 9 years ago cheated me, used pressure treated fir ... termites ate that one away. don't know if that's a good thing or not ...

 

Dan, i had considered using a hollow 4x4 metal tube, hadn't thought about an I beam. i was thinking, with the tube, fill hole with cement and the cement would fill the center of the tube.

 

i was thinking a tube as then i'd have 4 sides to drill on ... plus it won't lean.

 

but ... if i don't have enough room, there won''t be any cement around it, just in the center ...

 

maybe a 3x3 metal tube ??? that should hold a redwood gate, yes ??? hammer a rebar into the center of hole in the ground and then 4 more on each side of the 3x3 square steel tubing ???

 

ahhh more engineering on the fly ...

 

thanks, wayne

[SHO-Z]

Get some steel plate and some concrete 3/8" Hilti Bolts, you can rent a drill from a rental place. Cover the post holes with plate and attach with the Hilti Bolts. Get some square steel tubing to replace the posts above the ground and weld to the plate. You can weld attachments to the posts to attach the fence and gate.

 

This is a standard way to attach supports on concrete.

 

This would be my solution to your problem.

 

Have fun.

[Guest Want aZ]

SHO Z is exactly right. Hell we bolt barrier wall to bridge decks when doing bridge widening, It will work and really isnt that difficult, bole down steel plate then you could weld your post to the plate, place some reinforcement and your done....

 

good luck

 

Damon

[waynekarnes]

you think that the metal plate bolted to the cement with anchors would support a 45 lb 5 ft tall gate ? one on each post ? i had given that some thought, but was afraid the plates would come loose.

 

 

what type of Hilti Bolts would you use to hold that plate down ... i went to the web site, they offer about 12 different type of cement anchors. i figure some sort of a bolt system ?

 

i had considered bolting those metal 4x4 supports to the slab.

the type used to attach a post to cement, in my case the 4x4 slips through into the hole in the bracket into the existing 4x4 hole the cement, where the old post used to be and, then 18 to 24 inches into dirt below the cement.

 

thought if that bracket bolted to the slab, the redwood post sank into the dirt, bolt through the bracket, oughta hold the gate ...

 

maybe not ...

 

thanks, wayne

[Dan Juday]

Duh!

 

SHO and Damon have the answer. Stop drilling Wayne. I'd use four 1/2"x6" anchors in each plate. That will hold three times your gate's weight.

[Here comes trouble]

Go to Home Depot There are inexpensive steel anchor post brakets for 4X4 posts. Concrete the steel post pipe bottom in with the attached 4X4 bracket on top of the concrete where the 4X4 can be positioned between the brackets and lag screwed in place leaving the wood post above ground. I had some cedar posts that rotted out and made my own steel brakets out of 2X2 angle iron for the post and pipe driven 24 inches into the ground as anchors on opposite (2) sides of the post without cement . I used the same bottom rotted out cedar posts without dismantling the fence.... fence is still standing and especially strong where the home built brackets are after 15 years on a 35 year old fence..

[SHO-Z]

You need to figure how thick your concrete slab then use about 3/4" shorter bolts. Use the hiltis that you drive in and you tighten the nut to secure. They are cone shaped on the non threaded end. Try to keep away from drilling right next to your existing post location keep about 3" away minimum.

 

These will not pull out, the concrete would have to break out around them to fail.

[waynekarnes]

hmmm, once again, paid for something i apparently didn't get.

 

at the post hole the cement must have sank down along side the existing 4x4 when the cement was poured around it.

 

at the post i measure down 12 inches and still have cement.

 

i paid for 4 to 5 inches thick of cement.

 

i dug at the edge, where it meets the fence separating my neighbor's yard from mine.

 

cement is only 3 inches thick.

 

you think this will support those posts, with a 12x12 plate ??

 

... i was hoping, if i did this to hinge the gate off just one post. an 8 ft post, with a cable off the top to support the far end of the gate.

 

i'm afraid with only 3 inches of concrete, won't be enough to support the posts.

 

i'm thinking, 12x12 1/4 in plate with 4 bolts ... posts 8 ft tall, 4x4 inches , 1/8th thick wall, rectangular post. i see no reason to use a 1/4 inch wall thickness on the posts. or am i wrong there ?

 

if the cement isn't thick enough, i'm back to sticking em in the ground ...

 

perhaps ... a thought ...

 

maybe sink the metal posts a foot or so in the ground, through the plate, and weld the post to the plate ???

 

i might end up having to shim the plate, as where the posts are, the ground isn't flat ...

 

thanks for the advise, much appreciate it ... please add any thoughts you might have.

 

wayne

[Here comes trouble]

After about 60 days of cure that concrete will hold about anything including your motherinlaw