Appropriate depth of footing for a 2m block wall on clay?

[NeilPalfreyman]

My next door neighbor has had a single skin, 2m high block wall built between our gardens. I'm somewhat concerned about the structural soundness of it, considering that our garden is about half a meter lower than theirs.

I've had a look at the footings on our side and they go down about 30cm, but don't they extend very far from the edge of the blockwork, especially where the support pillars are located.

What would be a "reasonable" depth/width of footing for such a wall on clay?

 

[Dereekoo]

Whatever the structural analysis indicates which will be interdependent on the depth of the base, soil characteristics and the width of the footing. Whats required is an analysis of what is there at the moment to see if there is an adequate FoS against failure due to overturning/sliding/shear. There isn't a simple design chart/table that can be used

 

[noseall]

our garden is about half a meter lower than theirs.

Has the 'angle of repose' been considered when dealing with the depth of the foundations? We have dug down as deep as 1.6m in the past, because the neighbouring earth falls away steeply.

Irrespective, a 1.8m high wall deserves respect and a standard excavation is necessary i.e. through all the fertile black stuff and down to load bearing virgin earth - usually a minimum of 500mm or more. The foundations should exceed the width of the wall by at least 100mm on each face.

 

[^woody^]

Depth is measured from the lower ground level regardless, and at least 450mm would be common.