Trial pit for building brick pier

[Al@n]

I posted a thread previously regarding building a pier to support an rsj

Upon further discussions with the SE and in agreement with BC they've agreed I can build the pier with 7.3nm dense concrete blocks laid on its belly instead of the solid engineering bricks

The snag I have now is although the depth of the concrete slab is 28 inches deep, BC want to see how deep the foundation's are!

So i now need to dig a trial pit approx 1 metre deep to satisfy BC before i can build the pier!

whats frustrating is the SE at no point stated this will be required and at the time stated i could build the pier straight on top

Pic attached which shows the difference in height between the dining room and garage

https://www.diynot.com/diy/media/img_20190828_132953.103281/

Question i have is do i really need to dig 1 meter deep?

is their a specific area i should dig to show sufficient foundations?

I was planning on digging the trial pit on the garage floor left to where the pier will be built which is on the left hand side of the door frame, just where you see the white chipboard

 

[23vc]

Surely you only need to dig down to the bottom of the existing foundation, whether that’s 1m deep or less

 

[Al@n]

Surely you only need to dig down to the bottom of the existing foundation, whether that’s 1m deep or less

Yep, so I'll be digging a trial hole at the garage floor level close to the door as the pier will be built on the raised floor which is the dining room to get access to the foundations of the dining floor via the garage floor

 

[^woody^]

Would it be easier to dig on the outside?

 

[Charlie George]

I find it hard to believe the garage slab is 28 inch thick,how was you able to measure it if you have'nt dug a trial hole.

 

[Al@n]

I find it hard to believe the garage slab is 28 inch thick,how was you able to measure it if you have'nt dug a trial hole.

The dining floor slab is 28 inches thick, which is the difference in height between the dining room and garage floor

 

[Al@n]

Would it be easier to dig on the outside?

Outside where? This is an internal pier that needs to be built for an rsj so i can take the wall out between the garage and dining room

 

[^woody^]

Outside the house.

 

[JohnD]

The dining floor slab is 28 inches thick, which is the difference in height between the dining room and garage floor

Of that 28", how much is the slab?

 

[Al@n]

I've started to dig a trial pit, it ain't looking promising

The garage floor is 3" concrete below that is just filled in with sand

I've managed to get my hand just under the slab where the pier will be built where the breeze block is placed no foundations are underneath. The pier will be built in half dense 7.3nm breeze blocks

As the concrete slab doesn't continue below ground I'm guessing I'll need foundations?

https://www.diynot.com/diy/media/img_20190914_132746.103283/

I'm guessing I'll need to dig 1m deep and fill with concrete but how wide do i need to go?

 

[Al@n]

I've dug down approx 1.10 metres but now the ground is filling up with water! Approx 1 to 2 inches deep

I've sucked the water out with a wet vac but the water reappears back to the same depth

Have i hit hit the water table? Would this need to be addressed if so how?

Or can I just fill it with concrete once the BCO is satisfied of the depth?

https://www.diynot.com/diy/media/img_20190914_160456.103284/

https://www.diynot.com/diy/media/img_20190914_160507.103286/

https://www.diynot.com/diy/media/img_20190914_160829.103285/

 

[Al@n]

Bump, anyone?