Wide Footings

[adrian.groves]

i'm embarking on a self build house which will have a brickwork plinth around the bottom 3 courses. Unfortunately my neighbour has a basement and the building inspector has insisted on a 2m deep footing. I am expecting to put in a strip foundation and build up on top of it. Will I need to build up 3 courses of blockwork, or does anybody know an easier way?

Also the ground is suitable to take the footing after approx 1m depth but the inspector insists on a 2m deep footing although my neighbours basement is 2m away from my house. Does anybody have a view on that?

Thanks

 

[noseall]

[quote="adrian

Will I need to build up 3 courses of blockwork, or does anybody know an easier way?

i'm afraid so yes.

Also the ground is suitable to take the footing after approx 1m depth but the inspector insists on a 2m deep footing although my neighbours basement is 2m away from my house. Does anybody have a view on that?

theory states that a triangular section of ground will push downwards and outwards at 45 deg from the footing edge. this is what b.c. use as a standard.

Thanks[/quote]

 

[carryoncamping]

[quote="adrian

Will I need to build up 3 courses of blockwork, or does anybody know an easier way?

i'm afraid so yes.

Also the ground is suitable to take the footing after approx 1m depth but the inspector insists on a 2m deep footing although my neighbours basement is 2m away from my house. Does anybody have a view on that?

theory states that a triangular section of ground will push downwards and outwards at 45 deg from the footing edge. this is what b.c. use as a standard.

Thanks

He's not called Noseall for nothing!

I've seen a diagram of what Noseall describes somewhere, he's right. If you want a little bedtime reading you could always download the Building reg parts A to P at:
http://www.planningportal.gov.uk/england/professionals/en/1115314110382.html

 

[gangman]

The usual way for me is 4in inner skin, cavity then block on flat for plinth and external skin.
Like noseall said you look at the 45 deg. Your foundation can be above the bottom of next doors foundation by the distance between them. If you've been told to go down 2m , it could be a deep basement or the bco knows something about the site, maybe just over cautious. To be honest if someone was building around six foot from my house I'd want the bco to be cautious.

 

[^woody^]

You could have a chat with a structural engineer to see if there is an alternative option. The BCO can not argue with an engineers calculated design. Also the 45 deg guide is a general guide, and may not apply to all soils and situations.

My concern with such a deep (and wide) trench so close to an adjacent property, would be restraining the ground and preventing any movement of the neighbouring building. There are practicalities of actually excavating and shoring too. A piled foundation may be more appropriate and cost effective

Make sure you serve a Party Wall Notice first, to prevent any delays when you come to do the work, and I would arrange a survey of the neighbours property to record its current condition - else risk claims later

 

[JohnD]

There's a trick for filling an excavation like that with a sort of liquid clay called bentonite to stop it caving in, then you pump in concrete and the bentonite floats to the surface and is pumped away for re-use.
Never seen it done, it would be entertaining to try it. I bet you could sell tickets

If you end up with a 2M foundation, you might as well dig it right out and have a basement.