# Forum Home Renovation Sub Flooring  Under floor excavation for workshop/mancave

## Refgies

3 years ago I started excavating under my house to create a workshop/man cave. 
I planned the work in 3 major stages, the first 2 of which are complete. 
I have removed over 50 tonne of earth by hand, spanned out 25 brick piers and installed a substantial amount of structural steel with only the the help of friends to lift steel and a few of the slow days at work spent under there with the apprentice digging. 
I took a year off after completing stage 2 following the birth of my son. 
Workshop is in and functioning but the lure of almost doubling my work area has tipped me over the edge. 
Stage 3 has begun and involves the excavation work at the deepest side of the house, there is 3 brick nib walls 2.5M long here supporting what was the laundry and is still the bathroom and the toilet. 
to gain the ceiling height i desire stage 3 also en tales excavation of more than 500mm below the bottom of the strip footing along the back wall. (my current plan is to leave 1M of the earth at the back wall to maintain the integrity of the footing but am open to suggestions). 
I would love some advice on supporting the bath/toilet slabs both temporarily and permanently 
The pictures will tell more than I can

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## Refgies

How do I upload pics?

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## Refgies

This is the day I moved in looking back into the area to be excavated

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## Refgies

this was the end of stage 1,first 4 piers removed, 2 x 250UB25 in place of existing timbers and concrete floor poured

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## Refgies

stage 2 earthworks complete, several months spent here

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## Refgies

all steel in stage 2, leveling for concrete

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## Refgies

Attachment 111545

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## David.Elliott

Hey Admin.. 
Link to a YouTube video on how to upload photos onto here...  https://youtu.be/3ECEVV0rywY

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## paddyjoy

Can't help with your question but just wanted to say it's looking good, massive job!

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## Refgies

Cheers, I love every minute of it

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## Black Cat

I hope you have had engineering advice .....

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## PlatypusGardens

Good grief. 
that's a lot of digging  :Shock:

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## OBBob

> Hey Admin..

  Is there still an Admin? Lol.

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## OBBob

Amazing effort digging...

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## havabeer

i'm wanting to do something similar to my house actually, except i won't be moving 50 tons by hand...  
how do you plan on retaining the dirt and footings?

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## Refgies

after the slabs were down we drilled and chemset in starter bars, layed the blocks then filled with concrete and then aggregate behind the wall.. very solid

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## Refgies



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## Refgies

I used the retailing wall loss of space to create the main work bench

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## Godzilla73

Looking good, what's the head height like?

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## Refgies

Perfect for me, I'm 6 foot 3 and can walk under the uni beams without contact. Gave myself 10mm clearance

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## Spottiswoode

> Perfect for me, I'm 6 foot 3 and can walk under the uni beams without contact. Gave myself 10mm clearance

   Best keep your high heels for going out then  :Wink:

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## hrt22

Nice work so far...I'm also having a go at digging under my place....how did you go with permits and engineering?

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## Refgies

Permits not required as I am expanding storage space, the area is no habitable.
I had an engineer draw up steel size requirements and maximum spans etc.
I just take photos of my footing depths and he is happy.

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## Marc

So the council asks for a development application for a carport and nothing for underpinning the whole house?
Hard to believe
 PS
What happens if God forbid, a beam or pier gives way and you need to claim insurance?

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## havabeer

i thought you had to get DA's if your excavating closer then 1m of your footings

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## hrt22

I like it...wonder if my council in Melbourne are open to the same regs?

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## OBBob

> I like it...wonder if my council in Melbourne are open to the same regs?

  All works have to happen at night, without the use of powered machinery ...  :Smilie:

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## ColBatGuano

So how did you get rid of all the dirt? That would be a lot of money in skips. 
Around here (melbourne) a 4 meter skip costs around 350, so 50 cubic meters would be around $4200.

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## Refgies

I was waiting for someone to ask that..  
I am a sparky and the main wholesaler I use offers a skip bin to customers for rubbish disposal.
They also have a huge amount of empty boxes on offer.
Every day I would fill 8-10 boxes of earth (the boxes had to be re inforced with packing tape) and put them in the bin. The owners of the wholesaler didn't care as the bin was rarely full at pick up time and the cost was the same to them either way. I also weighed every box before loading into the van.
I got rid of around 50 tonne over 1.5 years in that bin.
At the end of the dig I had to use 4 skips at 8 tonne a peice (cost 500$ each) 
For the stage I am currently undertaking I have a more convenient way of dumping the soil via a friend semi near by with acreage and my ute

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## OBBob

You're not related to that 'great escape' guy are you?   :Biggrin:

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## ColBatGuano

"_to gain the ceiling height i desire stage 3 also en tales excavation of more than 500mm below the bottom of the strip footing along the back wall. (my current plan is to leave 1M of the earth at the back wall to maintain the integrity of the footing but am open to suggestions)._" 
I've seen youtube videos of companies (US) that do underpinning around the perimeter of a building from inside. They dig out a 1 metre (or thereabouts) section under the footings, put metal bars in, box it all up then concrete it.
Once it has set they move onto the next section.  
Not sure how they manage to waterproof it all though - perhaps they dig from outside later and put in a dampproofing membrane and drainage. 
There is a guy in Sydney who has done something similar for his townhouse. Apparently he managed to do it without affecting the neighbours walls at all.

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## paddyjoy

> I was waiting for someone to ask that..  
> I am a sparky and the main wholesaler I use offers a skip bin to customers for rubbish disposal.
> They also have a huge amount of empty boxes on offer.
> Every day I would fill 8-10 boxes of earth (the boxes had to be re inforced with packing tape) and put them in the bin. The owners of the wholesaler didn't care as the bin was rarely full at pick up time and the cost was the same to them either way. I also weighed every box before loading into the van.
> I got rid of around 50 tonne over 1.5 years in that bin.
> At the end of the dig I had to use 4 skips at 8 tonne a peice (cost 500$ each) 
> For the stage I am currently undertaking I have a more convenient way of dumping the soil via a friend semi near by with acreage and my ute

  Love it!   

> "_to gain the ceiling height i desire stage 3 also en tales excavation of more than 500mm below the bottom of the strip footing along the back wall. (my current plan is to leave 1M of the earth at the back wall to maintain the integrity of the footing but am open to suggestions)._" 
> I've seen youtube videos of companies (US) that do underpinning around the perimeter of a building from inside. They dig out a 1 metre (or thereabouts) section under the footings, put metal bars in, box it all up then concrete it.
> Once it has set they move onto the next section.  
> Not sure how they manage to waterproof it all though - perhaps they dig from outside later and put in a dampproofing membrane and drainage. 
> There is a guy in Sydney who has done something similar for his townhouse. Apparently he managed to do it without affecting the neighbours walls at all.

  "Ourbuild" did that to his place and has some pictures of it in his post http://www.renovateforum.com/f176/ma...vation-112896/

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## commodorenut

When I dug the footings for the retaining wall in the back room of the garage, I filled 20L buckets with the dirt.  
Put 2 of them in my weekly bin, and one in each of the neighbours.  Took about 6 months to finish those footings!

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## Marc

If only houses in Australia had cellars and attics from the start

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## OBBob

> When I dug the footings for the retaining wall in the back room of the garage, I filled 20L buckets with the dirt.  
> Put 2 of them in my weekly bin, and one in each of the neighbours.  Took about 6 months to finish those footings!

  Lol... at some point it just becomes a bit (I'm not sure the polite word? ). Anyway,  the point being doesn't that only work out to about 2 cubic metres?   :Biggrin:   
That said, good use of rubbish storage that was probably always unoccupied.

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## ColBatGuano

> When I dug the footings for the retaining wall in the back room of the garage, I filled 20L buckets with the dirt.  
> Put 2 of them in my weekly bin, and one in each of the neighbours.  Took about 6 months to finish those footings!

  We hardly put anything in our bin, so I've started filling it up with dirt. I can get around 100 litres/fortnight = 2.6m^3 a year. That'd make 20 years to remove OP's dirt!  :Redface:

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## OBBob

Wow, in our area the trucks have weight measurements in the lifters and won't take it if it's too heavy... we wouldn't get away with filling with dirt.

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## commodorenut

^^ That's why it was only 2 buckets maximum!  Never had an issue. 
Previous owner had dug out a room behind the garage.  He had a little crawl-hole to get in there.  
When we moved in, I cut a doorway into the non-bearing brick wall at the end of the garage, to allow better access. 
He'd dug a fair bit out, and replaced 2 piers with poles.  He stopped short of going as far as the next row of piers, and simply "rendered" the 1200mm high shale & clay mound that remained.
Problem was the "render" was only about 20mm thick, and after a year it began to crack & allow mini-landslides.   
So I dug out along in front of it & built a core-filled bessa-block retaining wall to hold it all back.  With reo in every hole, and 100% core filled, that wall will outlast the house!

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