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Wall corner tolerances


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I've spent the last week getting my corners absolutely plumb. I suspect the corner bracing on my ICF, which was fixed to the ground may have moved as clay dried?

 

Anyway, it made me wonder what tolerances are acceptable for wall corners? I asked a new build house and they said one of their walls was out by 30mm over 3m high :O which was done by a gang of brickies. They did go on to say they would normally find 10mm per floor (so I guess 2.5m) acceptable.

 

What would you accept?

 

Vijay

 

 

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Hello bud,


Well I hope they don't move too much! They're now braced to the scaffold and I hope that by the time I've circled with the concrete pump, the concrete will have started to go off...........

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29 minutes ago, Russell griffiths said:

[...]

I was surprised how much they move about with the concrete thundering in. 

[...]

 

Thats what 'got' to me.

The wall rocked from side to side as if being hit by a huge hammer - 10mm  back and forth maybe more.  Mind you then final pour, I couldn't have cared less. I just prayed for no bursts - a 20mm wobble is nowt - but a burst 3.5 meters up is no joke. 

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Nobody, except a self builder

just out of interest what has your icf supplier told you to do with the bracing. 

We were told to lean the walls IN towards the bracing as when the concrete goes in the weight of it pulls the wall away from the brace and the whole system goes into tension. 

I plumbed mine 10mm out of plumb leaning hard against the braces, when the concrete was poured it was nearly perfect and just needed a tweak. 

 

As a word of caution, you can push a wall away from you but it is hard to pull one back, so lean them in, if they fall out it is a bugger to get back and you can pull the screws out. 

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He didn't say anything about leaning it either way, just get them vertical. I'm a little concerned now as I'm almost dreading pour day (when it comes around) :(

 

What gave in your bracing? How was your bracing fixed into the ground/floor/any other way?

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The bracing is all steel, but comprised of 4-5 components, so a foot plate bolted to the floor SOLID a cross brace and a brace on the wall this is all really good, what happens is all components need to be taken apart so they are fixed together with a large steel pin and a circlip. 

This pin has a millimetre of movement in it, multiple this by 3 pins and you get a fair bit of play. 

What I found is that the wall doesn’t weigh much, so you plumb it up, but it’s not really tensioned against the brace as it’s so light, you then make it really heavy by filling it with 20 tonne of concrete, it then wants to lean one way or another so it tensions up all those little 1mm of play in the pins and this is when it needs a little tweak to get  it lovely and plumb. 

 

Its relatively straightforward, but don’t underestimate how many hands you will need that day. 

For the size of your place I think I would want 5 blokes

1 on the pump controls

2 on the hose

3 on the vibrator

4 cleaning up spills

5 running about untangling extension leads, looking for blowouts, fixing stuff. 

 

You will need string lines setup but out of the way so you can eye along the top of the wall as you plumb it. 

If you look at stones blog he has some good pics to show how to set the lines up using little blocks of timber at the corners, but I’m sure you know this stuff. 

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I'm gonna have to have a good chat with the ICF supplier as none of this is in the brochure lol

 

There should be at least 5 of us plus the pump operator, but as I found out when we poured the foundations, things can get hectic very quickly and in burst. Trying to get people to do EXACTLY what you want can be difficult as all of a sudden, some want to do things their way :(

 

Been told by the supplier many times that I should not use a vibrating poker in the walls, apart from around rebar cages..............................

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4 hours ago, Russell griffiths said:

We hardly used the vibrator on the second pour, just lots around the cages. 

 

Because you didn't see any point or something else??

3 hours ago, Conor said:

From my chats with an ICF builder, they work to a tolerance of +/-5mm per 10m.

 

Is that vertical or horizontal???

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Didn’t see any point, after it falls 2.7m vertically it doesn’t need any more vibrating. 

You will need to vibrate your cages VIGOROUSLY or you just won’t fill them up, this is a two man job one on the hose and one vibrating as fast as he can or you get concrete piling up and not falling through the re bar. 

 

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