Crack stitching

[Tim Lamb]

Ah! I've got one of those for my own use. You need big doors if you are going to assemble in comfort.

regards

[Huge]

Huh? :o)

[Tim Lamb]

I didn't understand it either. Something like the original foundation is not in direct contact with the underpin block but rests on a layer of hard rammed sand/cement mix. I thought you might be able to explain the reasoning:-)

regards

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[Tony Bryer]

Yes, you need to be sure that the existing foundation is fully supported on the new base. If you just filled the hole up in one go there would be no way of ensuring compaction at the back and the new concrete would shrink a little anyway. So, as described about, the top of the new base should be about 50mm below the underside of the existing footing and once it is hard the gap is filled in with 'dry pack', a mix of cement and sharp sand 1:1-2 with just enough water to hold it together. This is pushed into the gap and rammed tight with something like a hammer and piece of 4x2 so that the gap is fully filled.

[Tim Lamb]

Right.

Not the easiest job I guess, as you have just filled up the hole you were standing in and can't dig the next until you have properly supported the first bit:-)

regards

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[Andy Dingley]

I suggest reading a copy of "The Winchester Diver" before starting, then not complaining!

[Rod]

Agreed! Then he died of flu!

(Mrs Pierce, in this story about the diver, is my mother. )

[Tim Lamb]

I vaguely knew about that. Build not your cathedrals on a bog?

regards