Digging a 3000mm deep hole

[funkychicken]

I'm about 20kms from Toowoomba, what should I look under in the yellow pages?

[ian]

I'm about 20kms from Toowoomba, what should I look under in the yellow pages?

I just Googled
reinforcing steel Toowoomba
and got about three hits

what you should look for depends on what you intend building and that should be shown on your plans.

are your piers reinforced?
if so what is the specified reinforcing?
How are the timber stumps attached to the piers?
what tie downs do you need?

From what you've described here and elsewhere sounds pretty straight forward once you get 400mm off the ground.
Getting there from 3000mm below the surface could be the tricky bit.

I must admit I don't like the idea of stopping the concrete and starting the timber stumps 500mm below the natural surface — to me it sounds too much like a dinner invitation to the termites plus potential problems from the reactive soil backfilled against the timber stumps.
Can you elaborate?

[Greggy1]

We've just had to put in a similar foundation for our house. 48 of the b*ggers all 300mm diam and between 2.5m and 3.5m down.

Excavator or bobcat with earth auger is the answer. As the augur goes deeper, they undo the drive shaft and attach an extension and keep going.

Assuming you have to put re-bar down the hole as well. What our builder did was wire up the assemblies and had the concrete truck onsite. Excavator comes through, bores the hole, apprentice drops the reo in and holds it while concrete truck follows and fills it, 10mins per hole thanks for coming. I think 3 days and the whole job was complete

What that did was saved cost on cardboard or steel columns to stop collapses and meant the site was much safer as there were no holes at the end of each day.

Edge beams, waffle and slab followed, which raised us 200mm out of the ground, but probably more than you need to do by the sounds of it. I'd suggest approaching it like we did but maybe leaving the concrete 500mm from the top and dropping in your (presumably) concrete stumps inside the reo and pouring the rest the next day.

[ian]

I'd suggest approaching it like we did but maybe leaving the concrete 500mm from the top and dropping in your (presumably) concrete stumps inside the reo and pouring the rest the next day.

This is not a good idea as it induces a hinge and largely defeats the purpose of digging the 3m deep hole in the first place.

[funkychicken]

One detail on the plans says "4/N12 Bars. 75 Cover."

I'll take a piccy of the plans tomorrow.

The post go into the concrete, the concrete surrounds the posts

[Gingermick]

what about ligs? 4/N12 bars need to be tied together to go in a hole.

[funkychicken]

Ligs? There's an added note, "R6 Ties at 600crs Only if required to maintain specified coverage and spacing of bars"

[Gingermick]

that'll be them. It may be hard to keep separation and cover on the bars three metres down a little hole.

[Grumpy John]

How's the foundations coming along FC?

[funkychicken]

Well I've been thinking (or more correctly, my parents have been insisting) that instead of building a shed here I could buy a cheap bit of land (Unofficially subdivide a mates block) and stick it there, then put a house next to it.

So no holes in the ground yet. If I can't get a cheap bit of land then the shed will go here in Meringandan

[ian]

Well I've been thinking (or more correctly, my parents have been insisting) that instead of building a shed here I could buy a cheap bit of land (Unofficially subdivide a mates block) and stick it there, then put a house next to it.

So no holes in the ground yet. If I can't get a cheap bit of land then the shed will go here in Meringandan

be very careful, and pay for very good advice, if you really intend going down that path
because if you do "officially" every thing you build will belong to your mate