Hi,
I'm building an extension (I'm not a builder, but I've renovated a few houses and can do most things!), and want some advice on underpinning.
The project involves knocking down some of an existing single storey extension to the house, and building a 2 storey timber frame extension. It also involves knocking the second (really it's 1.5th) floor off of an original part of the house, retaining the ground floor.
The architect and SE have decided we can keep the existing floor slab + foundations, but will need to partially underpin with several 600mm square pads.
I've dug some of the pads under the modern concrete foundations, and don't see the need for any support etc (no movement or cracking).
However, I'm a bit concerned about the original walls, as they just corbel out by a brick width, and are then sitting on soil (clay). If I dig a 600mm wide hole underneath 100 year old brickwork, is it likely to stay in place? Or am I going to be saying goodbye to a section of the wall? This is a 9in solid wall if that makes any difference.
I also can't see the reason for needing the underpinning on this part of the extension - surely a half storey of brick that's being removed weighs more than the full storey timber frame that's replacing it. And the rest of the original house will still be sat on corbelled brick and soil!
Thanks.
I'm building an extension (I'm not a builder, but I've renovated a few houses and can do most things!), and want some advice on underpinning.
The project involves knocking down some of an existing single storey extension to the house, and building a 2 storey timber frame extension. It also involves knocking the second (really it's 1.5th) floor off of an original part of the house, retaining the ground floor.
The architect and SE have decided we can keep the existing floor slab + foundations, but will need to partially underpin with several 600mm square pads.
I've dug some of the pads under the modern concrete foundations, and don't see the need for any support etc (no movement or cracking).
However, I'm a bit concerned about the original walls, as they just corbel out by a brick width, and are then sitting on soil (clay). If I dig a 600mm wide hole underneath 100 year old brickwork, is it likely to stay in place? Or am I going to be saying goodbye to a section of the wall? This is a 9in solid wall if that makes any difference.
I also can't see the reason for needing the underpinning on this part of the extension - surely a half storey of brick that's being removed weighs more than the full storey timber frame that's replacing it. And the rest of the original house will still be sat on corbelled brick and soil!
Thanks.
