Foundations

[Akka87]

Hi all I am starting to dig my footings this weekend but while I have the machine I was Going to dig the over site out aswell my drawings for my foundations are 1m down etc is this from finish floor level
My second question the over site my architect is suggesting is around 470mm below ffl down I thought I could kill 2 birds with one stone reduce dig it down and then dig the foundations around 600mm less or would I then have to go meter down from digging the over site

 

[Notch7]

The rule of thumb 1 metre down is from ground level....assuming a level site.

However it depends on your site. Very hard ground, say mudstone or sandstone it may be less, for shrinkable clay....could be any depth. Basically you have to reach load bearing ground

Reduce dig for a slab is typically made up of:

150mm hardcore
50mm sand blinding
100mm concrete
70mm celetex
65mm screed
25mm floor finish

Generally the foundation trench is dug first with the digger straddling the trench, then the oversize is dug

 

[Akka87]

Yeh my only issue I have once floor is up to slab hight I won’t be able to get the machine back in reason I wanted to try dig the over site also. And save on the hand dig

 

[noseall]

Yeh my only issue I have once floor is up to slab hight I won’t be able to get the machine back in reason I wanted to try dig the over site also. And save on the hand dig

We ALWAYS dig the oversite at the same time as the trenches. We also dig off a 1.2m swathe around the proposed building and stone that up too.