Ideas to remove these post ties?

[couch67]

Hello GJ'ers,

A few years ago I put in a slab for a hot tub and planned to build a gazebo. We've had the hot tub in place without the gazebo for a year and a half, and we love stargazing while in there. We've decided not to build the gazebo for that reason, and instead build a pergola.

The one problem - I had planned for the gazebo and installed a bunch of these post ties when the slab was done. These have a sizeable chunk of rebar welded to them that embed into the concrete. By building just a pergola, I'm not going to need all these ties. We thought about building a half wall /railing around the whole thing but I thought that might look dumb. Thinking my only option is to drill them out.

I have a few questions:
- I'll need to drill a fair size hole - 5/8 or 3/4. None of my portable drills are up to that task. Is there the equivalent of a mag drill that would be worth renting?
- how far into the rebar should I drill before patching with cement, so rust/ghosting is not an issue in the future?
- would you drill a pilot hole first, then go with the bigger drill size?

thanks in advance for any feedback.

 

[acer66]

If you want to get them completely out I would rent a core drill.

 

[Drill Sergeant Arc]

We sometimes make a jig out of polycarb or sheet aluminum or even 1/4 ply to hold a hole saw in position minus it’s center bit to remove the above surface metal. It has the hole saw’s outside diameter in it that can be held in position as a guide to hold the hole saw to first remove the outside sheet metal bracket. Then the imbedded bolt or in your case, the rebar can be removed by diamond core drilling the surrounding concrete. You can core really close to the outside diameter of the rebar imbed. Then fill the hole with grout.

 

[Garcky]

Hello GJ'ers,

A few years ago I put in a slab for a hot tub and planned to build a gazebo. We've had the hot tub in place without the gazebo for a year and a half, and we love stargazing while in there. We've decided not to build the gazebo for that reason, and instead build a pergola.

The one problem - I had planned for the gazebo and installed a bunch of these post ties when the slab was done. These have a sizeable chunk of rebar welded to them that embed into the concrete. By building just a pergola, I'm not going to need all these ties. We thought about building a half wall /railing around the whole thing but I thought that might look dumb. Thinking my only option is to drill them out.

I have a few questions:
- I'll need to drill a fair size hole - 5/8 or 3/4. None of my portable drills are up to that task. Is there the equivalent of a mag drill that would be worth renting?
- how far into the rebar should I drill before patching with cement, so rust/ghosting is not an issue in the future?
- would you drill a pilot hole first, then go with the bigger drill size?

thanks in advance for any feedback.

So, how many of those are there on that slab? If it was just the three in the photo, I'd build a sitting bench that used them. If the whole slab has those, then I'd probably remove them.

 

[couch67]

Yeah, there are a total of 12 in the slab. So the 8 interior ones would go. The sitting bench is an interesting idea!

 

[couch67]

We sometimes make a jig out of polycarb or sheet aluminum or even 1/4 ply to hold a hole saw in position minus it’s center bit to remove the above surface metal. It has the hole saw’s outside diameter in it that can be held in position as a guide to hold the hole saw to first remove the outside sheet metal bracket. Then the imbedded bolt or in your case, the rebar can be removed by diamond core drilling the surrounding concrete. You can core really close to the outside diameter of the rebar imbed. Then fill the hole with grout.

If you want to get them completely out I would rent a core drill.

Great ideas!

 

[Drill Sergeant Arc]

So, how many of those are there on that slab? If it was just the three in the photo, I'd build a sitting bench that used them. If the whole slab has those, then I'd probably remove them.

Sitting bench, shooting bench, tomato/to-mato

 

[Walkers]

I would just twist the tops off, then use an angle grinder with a cut off wheel and make a cut from inside and a cut from outside to get rid of a half inch of the rebar. Then use a chisel to even up the divot in the concrete (or use a concrete cutting wheel in the grinder. Use a concrete patch product and done.

Most of the time the steel is just cut off flush and left that way.

 

[Leaflessshadetree]

It looks like it might be a drop from the slab to the ground, a railing, bench or table /bar wouldn't be a bad idea. A 3/8 drill would be enough to drill through the plate but 1/2" woule be better. Center punch at the center of the rebar. Start with a 1/8" (or slightly larger) bit go 1/4" deep then use larger bits until you get it off. Use oil, plenty of pressure and keep the drill speed low. You want chips or spirals as the drill cuts.
Honestly I'd probably just grind the center with an angle grinder and leave the rebar flush with the surface.

 

[tarmy]

Sawzall them off then take a flap wheel and grind them flush. They also make concrete smoothing/grinding wheels you could use it the conc is roughed up under them.

 

[Renegade1LI]

One piece of rebar each, cut off with grinder, chip around the rebar then cut about 1/2" down with the grinder. Get some sika patch & finish to match, rub with a piece of styrofoam as it sets up to blend in. If you're worried about rust cap each rebar with some epoxy.

 

[Dig Doug]

Sometimes the fix looks worse than the actual bracket.
cutting and patching will look like a cut and patched concrete slab

can you make an Open trellis or a structure using the brackets, I left a 4x4 opening above my hot tub so I could see the stars at night and used 3x4’s to add some shade during the day.

What about just making a wood style TREX deck, Flagstone, brick etc above the concrete and just covering over the brackets.

what about a planter box, bench, raised vegetable garden so they aren’t visible

build a small box and set a potted plant on the small box that covers the brackets

 

[jack stand]

A waist high privacy kinda fence came to mind to use the perimeter brackets but I like the bench idea also. You will have to deal with rust whatever metal you cut off flush along with the previously mentioned possible surface differences.
A mag drill is a magnetic base drill, no use for your slab. The rental places will have a rotary percussion (hammer drill) that will do you drilling.

 

[nadogail]

An angle grinder will make those Post Bases dissapear, a little work with a single jack and a chisel will leave a small divot that can be cleaned up and filled with hydraulic cement.

 

[jblnut]

I'll cast my vote to use them for something. The bench is a great idea and I like the idea of a flower pot or something to cover them up instead of removing them.

Next year we'll have a thread "How do I weld onto rebar in my concrete that is under a recent patch" as you'll regret cutting them off for an unknown right now reason lol

 

[Spud McGee]

An angle grinder will make those Post Bases dissapear, a little work with a single jack and a chisel will leave a small divot that can be cleaned up and filled with hydraulic cement.

Yep. I was thinking an angle grinder with a cutoff wheel.

 

[The Cobbler]

just as you get the plates all off, you will decide you want a Gazebo again.
I am in the camp of leave them & build something to hide them or make it look like it was your plan.
removal will probably look a whole lot worse

 

[Ricky Joe]

I like the short fence idea. Keeps the deer/moose/elk/bear discouraged and keeps options for the future open to you or a subsequent owner and if you remove the hot tub you’ve got a shed foundation. Fence could have a bench, bar, etc. And removing them will take a lot of work and never look good.

 

[rayra]

If those brackets are welded to rebar rods projecting below into the slab, I'd drill out the top 1/2" of so of the rebar, akin to drilling out a rivet. And then put a dab of concrete gap sealer into the resulting holes to seal off the remaining rebar and fill them flush to the surface.

Seconding the perimeter bench post idea.

 

[couch67]

Quick update - finally got around to building the pergola. Will have to post more details on that. Here is a current pic, the structure is done. A few brackets to form up to support the tub shutoff, and remove the unused post brackets.

I used @Drill Sergeant Arc 's suggestion to use a hole saw to drill out the brackets (4 of them in total). This worked great! Underneath, there was a depression made by the bracket, and each one had about an inch void around the rebar. Good news for me.

I was set on coring out the rebar, and was going to rent a machine today (called yesterday) but everything is booked up this weekend. I could wait, but after seeing the depression and the void, I'm thinking this will be short work for a cut-off wheel in the grinder. Because the 5 1/2" square area is going to need a bit of a concrete and the void there around the rebar already, I think the grinder will get in there pretty easily, and will be hidden by the skim coat anyway. Should be able to cut the rebar down by 1" or more.

I plan to prime / paint the ends of the rebar, then float the depression with a parge skim coat or other repair product. Most are out of the way but the one in the front of the pic is front stage center. Any suggestions on a product that will hold up to foot traffic, and won't stand out like dog's balls?

 

[Zeke]

I wonder if you can lay a flat 4 x 4 in those, run a couple of screws and twist them until they break. If the rebar bond is a bad as you say, maybe you can drive them down with a large drift.

 

[couch67]

Thanks for the suggestion, @Zeke . I think it was just the top inch or so that had the void, when they pressed the brackets in after placing and finishing the pad. Its a thickened edge slab (13") so the 6" long rebar won't poke out the bottom.

I would have liked to try the twisting suggestion, but I read it a bit late. In the end I cut them all off using the method in post #20, then used a cutoff wheel to cut down the rebar stub to about 1" below surface, and then painted the visible rebar with a rust paint. Bought some quickrete patch compound, and will fill the areas once the rain stops and things dry out a little.