How does under pining work?

Answer 1

THEY DIG UP SOIL ROUND YOUR HOUSE, UNDER YOUR FOUNDATIONS AND THEN FILL THE HOLE WITH CONCRETE

Answer 2

Hi Monty - Here in the UK underpinning is done in, say, 1200mm sections at a time,it depends on the structure. They will dig down to a suitable depth, usually specified by a structural engineer. They will excavate, say, a 1200mm section, leave the next section undisturbed, then dig out another section. They will do this all along one wall, or more, it depends on specific conditions. This excavation will be filled with concrete. When the concrete is dry, they will excavate all the sections previously untouched and dig out and repeat the concreting process. Sometimes, as the concrete dries it shrinks a little. This narrow gap is 'dry-packed' - with dry concrete (no water) and this is forced into the gap and it absorbs moisture from the air and sets.

Edit -
boyboy - Interesting point about the dry-packing. I've seen underpinning done where dry-packing was specified by the structural engineer. Still, what do they know :-))

Answer 3

here in the UK we normally excavate a metre lenght at a time ..leaving as much in between but never excavate two corners at a time ..this excavation is normally a metre deep sometimes we insert miniacrow props ..sitting on solid concrete blocks ..these are normally left in when you concrete these days .the concrete must be machine mixed ..and very important ..it must be vibrated from bottom to top .. you would amazed how much this consolidates the concrete ....i never dry pack ..don't trust it ..always overfill footing and vibrate until all hollows are filled ..and i have never had to go back and repair any cracks ..some buildings i have done were six storeys

Answer 4

Underpinning is a method of stabilising subsidence in a building.The earth is excavated from under the foundations where the problem is and then filled with concrete.Hope this helps.

Answer 5

you've had an assortment of answers here haven't you.
some of them being writ by some right crack pots.
underpinning is normally carried out to strengthen a section of the foundations of your house where there is in tented to increase the load. it is rarely carried out to stop subsidence, but used where subsidence has occurred and all movement stopped.
take the leaning tower of pizza for example: no amount of underpinning will ever stop that from moving.
and underpinning a moving property could cause more damage....

Answer 6

In cases of subsidence, underpinning is pouring concrete under the structure to stabilise it.

Answer 7

I'LL FINISH.... THE HOLE SUPOSEDLY GO DOWN TO STABILL SOIL & ARE THEN PARTIALLY FILLED WITH CONCRETE... THEN THE HOUSE IS JACK UP LEVEL, CONCRET BLOCKS WITH STEEL SHIMS HOLD IT IN PLACE, & THE HOLES ARE FILLED WITH CONCRETE.