footings next to a boundary that drops down about 1m

[aspark]

hi i am a new member .im hoping to get some help.

we are building a rear single extension out of block ( with cavity ) and rendering it, its the whole width of the house and 3m out.

The boundary on the right drops down about a metre or so into the neighbours garden as the neighbours garden is at a level 1m or so below ours. .it is a concrete retaining wall thats not that thick.

This boundary is about 1m or so away from our house ( hence the entry leading up the side of our house )

I cant seem to find any information on digging my footings next to this drop,
how would it effect the depth of my footing if at all,? My gut feeling tells me it would effect the depth ..could anyone shed light on this i would be grateful
thanx

 

[^woody^]

You'll need to go down to at least the lower ground level for the foundation bottom, and probably plus 200mm.

There may also potentially be an issue with the force of the ground behind the foundation wall (ie under the new floor) trying to push the wall out - and there being too little support from the outer ground or the retaining wall

Site circumstances will affect this, and your designer should have taken this into account - if need be there are various ways to deal with this

Also, have you located the drains, as building control may want you to go down further if drains are below

 

[aspark]

Thanx for that reply ,woody.

I assumed that may be the case going deeper. We aint had any plans drawn up yet, so i was just trying to get ahead with the way i was approaching it.

With the drainage i was assuming we was at the end of the run from the left, because of the drop on the right. After what you have said it sounds like that might not be the case..I hope the drains are not that deep that would be a pain..!

I have a soil stack on the back of the house and i know the drains are 6m away from the house so thinking about it the main drain couldnt be that deep otherwise the fall would be too steep.!

With the footing on the right being so deep does it all have to be that deep or could i just step it up from the right to normal size footings?

 

[^woody^]

You really need to wait for whoever is drawing the plans to come up with a suitable foundation design

You can step the foundation up from where it does not need to be so deep

Regarding drains, you need to check with Severn Trent or whoever to make sure that you don't have public sewers within 3m of the extension - if so you will need their permission to build over or near to them