Stumps already in place

Hi, I am going to do a house extension over an area that already has stumps in place. How do I communicate on the plans that the stumps already exist and they meet the correct requirements? And do I need to prove this somehow?

I know they meet correct requirements as I built the deck that is currently there. Type M soil, 100 x 100 concrete stumps in a 600 diameter hole, with a 200 concrete sole plate and 200 concrete up the stump, then 200-300 rammed earth.

Any help appreciated.

if the deck was built with building approval the building department would have inspected bore holes prior to filling and issued an approval certificate and yes you need to prove this. requirements for a deck are probably not big enough to support a house
on plans just show "existing piers"

Unfortunately the deck did not require building approval, so I never sought it. The stumps were at the time built to take a house, hence why I used the above mentioned specifications.

So my next "dumb" question is how do I prove the specifications of the stumps now? I really don't feel like digging them up.

Thanks for the information for the plans.

do you have any photos, council may accept photos
otherwise . i think you will have to dig them up

I don't like your chances but you will need a another soil test and they will need to do at least one footing probe to confirm everything.

Remember even though the soil hasn't changed the Aus standards have several times over last 10 -15 years.

Things may have changed on site for example a tree may be growing nearby or moisture conditions may have changed eg.

excessively wet or dry changing the site to a "P" site so you need a soil test to confirm site conditions.

Hi insider,

I understand standards change all the time. I looked up the new standards for piers in Victoria and these still either match or exceed them. (I like to over engineer things).
Also a 75square metre shed was built within 1 metre of where these stumps will be in the last 18 months, pretty sure my soil hasn't changed.

So my big question is how do you do a footing probe?

I also am going to try and ring and talk to a building inspector in the next few days to see what they say.

Thanks for all the information and help.

A footing probe is basically digging up the full depth of a stump in your case and measuring the dimensions and the founding soil, you will need to know bearing capacity of the soil directly below the bottom of the footing.This is why a engineer or building inspector will ask for another soil test because you won't be able to determine the bearing capacity of the soil.
You never know maybe the will use your info good luck.

The building inspector should give you the same advice as Insider gave you Plus
There is a high chance the footings are non-compliant in which case an engineer will need to certify them as equivalent to what is required in the relevant parts of the Australian Standards, Generally there will be 3 parts to codes
1.Simplified
2 .Calculations (Principles Expanded)
3.Simulations
BTW, you can do all the comparisons, calculations and investigative work you want, it's the engineers licence number that's required on the plans and the regulations are tightening as a result of the new engineers Act and recent Structural Building Inspection failures here
Cracked Building Highlights Certification Problem