Add 2nd storey to existing extension

moneyuser

In process of buying house with existing extension, built 1985. Ideally, would like to add 2nd storey. The existing planning doc says the following about the foundations;

600mm X 250mm conc strip founds to comply to CP 2004 1972 to min depth of 610 MM or as determined by L.A
50mm site conc. on 150mm hardcore

Would this be suitable to add another storey?

Typhoon2000

No idea, but I wouldn’t rely on any planning docs. You would need to dig some holes and get a structural engineer to work out if the foundations and walls are ok to support another story.

Doozergirl

moneyuser said:

In process of buying house with existing extension, built 1985. Ideally, would like to add 2nd storey. The existing planning doc says the following about the foundations;

600mm X 250mm conc strip founds to comply to CP 2004 1972 to min depth of 610 MM or as determined by L.A
50mm site conc. on 150mm hardcore

Would this be suitable to add another storey?

That says the minimum planned, not the actual.  You'll need to dig trial holes to establish the actual depth but the minimum then was not good enough to meet current regulations where the minimum is a metre deep.  

weeg

Foundations completely depend on what the ground is and how well they are constructed, as well as the load on them.

So, the answer is 'maybe'. 600x 250 is pretty typical for housing in reasonable ground.

The minimum depth also varies with soil and location. (I hesitate to disagree with Doozergirl on this - or anything - but I'm not sure of her source of 1m depth)

stuart45

weeg said:
(I hesitate to disagree with Doozergirl on this - or anything - but I'm not sure of her source of 1m depth)

The best source of information is BS8004. If you've got access to the Construction Information Service you'd read it for free.

weeg

stuart45 said:

weeg said:
(I hesitate to disagree with Doozergirl on this - or anything - but I'm not sure of her source of 1m depth)

The best source of information is BS8004. If you've got access to the Construction Information Service you'd read it for free.

Also the NHBC Standards. BS8004 specifies 750mm min for clays, 450mm for frost. Nhbc goes into a lot more detail. It really varies across the country. 600mm is pretty typical across the central belt of Scotland.

Doozergirl

weeg said:

stuart45 said:

weeg said:
(I hesitate to disagree with Doozergirl on this - or anything - but I'm not sure of her source of 1m depth)

The best source of information is BS8004. If you've got access to the Construction Information Service you'd read it for free.

Also the NHBC Standards. BS8004 specifies 750mm min for clays, 450mm for frost. Nhbc goes into a lot more detail. It really varies across the country. 600mm is pretty typical across the central belt of Scotland.

I won't argue as I completely respect you! but it's every conversation with building control we've ever had, though I'm including block work, so the dig depth rather than pour.  Maybe that's where we're differing. 

stuart45

I think weeg was talking about dig depth as well. 1 metre deep in clay soils provided there's no trees close by is quite common with Building Control, as it covers for the higher volume types of clay. 750mm minimum is only for the low shrinkable types of clay. Even when you get to the required depth, I've known the BCO drive  a piece of 2x2 into the ground and want the trenches dug out deeper.