How can I install anchor bolts for a fence post base on a wall where the top layer is just an upturned breeze block covered in a thin layer of concrete?

Submitted by BigBlueMountainStar t3_z3j70b in DIY

The cowboy builders that built a communal wall a few years ago just put the top level as an upturned breeze block and finished it with a thin layer of concrete. All the walls that I had done have u-channel on the top layer and that is filled with concrete, allowing me to get a good base for heavy duty anchors.
However, for the remaining section of all (about 6m in length) the wall is hollow so I can’t use the usual anchor bolts. I thought about using the plastic cages with the epoxy, but I think it won’t work with the cage being vertical, all the epoxy will squeeze out and get dragged down by gravity!
I need a fairly robust anchor as it’s quite windy where we are so I need something to clamp. The thickness of the block plus concrete layer is about 20-25mm.
Hope the question makes sense

TL:DR need a high strength anchor to attach fence post base to top of wall.

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69Dankdaddy69 t1_ixly2pk wrote

Can you full the gaps with some concrete of your own so they're solid?

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a_broken_lion t1_ixly3ql wrote

Some of this is hard to follow without seeing it. I'm thinking maybe sandwiching 2x2 steel plates on either sie with 1/2" all thread and hardware (if you can access both sides)?

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BigBlueMountainStar OP t1_ixm1stt wrote

Replying to 69Dankdaddy69 (#648,661)

This is one thing I’ve discussed with my mate, but the anchors I’ve got at 12mm dia so I won’t get the concrete in through the bolt holes. We’d have to cut open a hole with an angle grinder to fill (which in itself isn’t a problem as the base would cover the hole, but I’m wondering if there’s an anchor solution that would solve it without this extra work)

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69Dankdaddy69 t1_ixm41x6 wrote

Replying to BigBlueMountainStar (#649,150)

From what ive read, the fence is breezeblocks, except theyre on their side so the hollow bit is vertical, is that right?

And then on top is a layer of crete to cover the hollows?

If so, could you just crack away the capping crete with a hammer? That would give you access without messing around too much.

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howard416 t1_ixm439l wrote

You really, really need a diagram for this. The title is a perfect example of r/titlegore

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yawningangel t1_ixo76ll wrote

You mentioned cowboy builders right at the start and are now asking how to keep going down that route.

You might be able to find a workaround using the existing footing, but it's more than likely you will put a lot of time and effort and the end result will be a substandard product.

Pull out the blocks,dig a hole and lay new concrete.

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