Probably Covered a Million times....

[Steted21]

Hi All

Im currently digging out the footings for a rear extension. The ground height outside sits at one brick course below DPC. I have then dug down and found 3Brick courses and two block courses to the foundations of the original house. I have dug down a little past the foundation say 400mm at the moment. so In total the strip is at about 1m+ at the moment. My question is the builder has stated to dig the foundations to 450mm by 1100mm and wait for building control to inspect them. Now does this mean 1100 from the top of the foundation?

Thanks in advance as I know this has been asked a millions times before

 

[John D v2.0]

No from the existing finished ground level. If it's not flat you'd need to step the foundation. The trench must be square and flat

 

[^woody^]

Listen, for the millionth and one times... Foundation depth is from ground level.

Btw it should be 600mm wide for a cavity wall, and 1000mm deep is normally adequate if the ground is good.

 

[phil parker]

When we built our single storey extension I excavated a metre down from existing ground level only for the planning officer to state I had to go lower than the top of the main house footings which were about 300mm lower . The mini digger had been returned and I wasn't looking forward to hand digging when the officer said as long as i put reinforcing mesh in it'll be ok

 

[Aeron Rees]

I hope it was the building control officer that asked you to do that and not the planning officer, the planning officers don’t generally get involved with the technical, construction process.

 

[noseall]

I excavated a metre down from existing ground level only for the planning officer to state I had to go lower than the top of the main house footings which were about 300mm lower . T

Standard.
There will be a reason your house footings are at that depth. It may be that the ground around your house was artificially built up. Whatever the reason, you would always expose the existing footings and dig yours to match, even if it means going down 2.4m like wot we did once.

 

[phil parker]

I hope it was the building control officer that asked you to do that and not the planning officer, the planning officers don’t generally get involved with the technical, construction process.

Yes it was building control.