# Forum Home Renovation Pergolas, Gazebos, Strombellas & Rotundas  Setting steel posts in concrete - floating method

## eek

So I've got a dude coming in tomorrow to bore 450dia holes down to 1000 for my post holes. Cement truck will be here the day after.  I'm going with 70x70x4mm square HDG posts with adjustable tops. The rest of the house sits on these so I thought I'd keep it consistent.  Top of posts have a 8mm thick plate which I secure into the bearers with 2*M12x100 coach bolts.  Posts are 2200mm overall, so 1000mm embedded in concrete and 1200mm above ground, supporting flyover roof and deck. 
I was looking online and found this 'floating' method of setting steel posts into concrete:     *Method 1: Traditional method*
Dig holes
Re-setup string lines
Set posts plumb and brace
Pour concrete
Check for plumb  *Method 2: Float method*
Dig holes
Pour concrete
Re-setup string lines
Float posts plumb and brace 
Can't think of any real advantages going the second method except the insides of the posts would be filled with concrete. Stronger? Method 2 means I could probably have less risk of paying concrete truck wait time if I need to be carefully filling holes not to bump the post too much.

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## Marc

Go with the method you feel more confident with, the end result is what matters, that is all post in line and levelled. 
My comment is that 70x70 at 1.2 above ground is too smaller section unless you have a lot of bracing. I would go with 100x100.

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## Optimus

> Go with the method you feel more confident with, the end result is what matters, that is all post in line and levelled. 
> My comment is that 70x70 at 1.2 above ground is too smaller section unless you have a lot of bracing. I would go with 100x100.

  Serious??? 
There is 1000mm in the ground filled with crete!  
We use 75x75 x4 and use hoop iron bracing when 1500 out of the ground... and our holes are certainly not 1000 deep..

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## eek

> Serious??? 
> There is 1000mm in the ground filled with crete!  
> We use 75x75 x4 and use hoop iron bracing when 1500 out of the ground... and our holes are certainly not 1000 deep..

  
Hahaha, yeah I know right.
Got a geotech test done around my house and it's just clay. It's all clay. Clay for days. 
They'll be braced with hoop iron unless I can find some cheap threaded rods to weld on, but I don't particularly like doing on-site welding.

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## huntercg

To a novice this method looks pretty simple.. https://youtu.be/GmiC5S2jlUM  
Sent from my iPad using Tapatalk

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## Marc

> Serious??? 
> There is 1000mm in the ground filled with crete!  
> We use 75x75 x4 and use hoop iron bracing when 1500 out of the ground... and our holes are certainly not 1000 deep..

  And it could be 2 meters deep and it would make no difference. The steel will flex not because the soil will move but because it is of smaller section (70x70x4). and it is 1.2 above ground. 
In my opinion of course.

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