# Forum Home Renovation Sub Flooring  Portal frame footing

## Andy Mac

Hi there,
I've been dragging my feet over the erection of a portal frame which an engineer specified for our removal house house/extension. It supports one side of a full-size carport (7m long), the other side being fixed to the house which is 3m away from the portal frame. Due to access problems the bobcat couldn't get the auger in to the exact spot for the footing....house eaves, Acro props etc. He drilled it 1300mm deep, but 300mm or so from the right place... with my OK :Redface: . Today I dropped a plumb bob and extended the hole, so now there is more or less a figure eight double hole. Crow bar and post-hole shovel in clay, down 1300mm! 
My question then is, should I somehow shutter the hole, putting form-work down through the waist of the extended hole to reduce the size, and therefore concrete, or should I just accept its a blurry big hole and use a third more concrete than should have been!? I reckon I should halve the hole with form-work, and back fill with spoil, tamping down as I go...but maybe not kosher.
Another question, on the ends of the uprights that sit in the holes, what is the accepted fixing to the RHS to bind it in the concrete? Does reo bar normally get welded to the RHS, and then wrapped about, or would a simple piece of scrap RHS welded at right angles at the bottom suffice? BTW, the engineer has specified 150x50x5mm RHS for the frame, OTT in my eyes, and cost about $900 in steel! 
Thanks for reading, I look forward to some pointers.  
Andy

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## Andy Mac

Just thought I'd show you the size of the extended hole! :Tongue:  
Cheers,
Andy

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## brynk

you could put a shutter in as planned but then backfill with the soil that you dug out (looks pretty clay-ey), tamp (compact) every 300mm or so. if you have a gal post with a post-cap lying around i find them to be quite effective - turn it up and fill it with some clay also to get more weight behind it.  re welding & reo - no reo doesn't usually get welded to the base of the column. as conc. & steel have very similar expansion/contraction rates then once cured they will act as a composite mass. but welding on the scrap rhs would be fine - you might consider putting it at 45 degrees so it is easier to get concrete inside  the rhs' hollow to make it completely bomb-proof!

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## Andy Mac

Thanks brynk!
Sounds like I'm on the right track, will cut some ply to suit. I made a fairly efficient tamper out of my crow bar, by welding a small disk of mega truck leaf spring onto one end. The clay should compact OK.
Good idea about angling the welded RHS :2thumbsup:  Between that and a reo cage in a hole that deep, the column shouldn't budge!
I won't have any excuse now... 
Cheers

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## Bloss

You could frame up and back fill as suggested, but if you have access to somewhere that has concrete stormwater pipes new or used then that can be an easy option. Even new ones are not all that expensive and come in different diameters and lengths (eg: 300Dx1200L or 400Dx1200L etc ) flanged and unflanged.  
Simply up end it in the hole in the right position then back fill around tamping as you go - I use them flange down. Simple and effective formwork that I have used on many occasions to save time and labor (and to fix a mistake or two!). 
Especially useful in loose and sandy soils as they can be placed quickly to prevent collapse if the pour is likely to be delayed. This can work too where you need to extend a footing/ pier out of the ground with the reinforcing or post extending the correct amount under the ground level - the pipe just remains in situ.

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## Andy Mac

Hi Oldbloss,
Thanks for the suggestion. I'm sure its a good strong fix, but I don't have any old pipe laying about. Have been eyeing off a couple of lengths pulled up at local road works, but was thinking more of laying it in a contour bank/ditch on our place so I can drive across. 
Cheers,

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## sports fan

you could use an offcut of corrugated iron or any sheet metal to form a column then you dont have to worry about recovering/ stripping it after.. seen guys use blocks of polystyrene as formwork before in tight situations were they cant strip a shutter, they pour deisel over and burn it out after. have a good1

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