Underpinn bay window

[trevorbayliss]

I am underpinning my bay window. I dug out the first section today and got down to the brick spread foundation. I am down 650mm to the top of the brick spread foundation.

Do I now need to go under this foundation or could I just clean up what I’ve done and add the concrete.. the bay has pulled away from the main wall hence I am strengthening the foundation and then I will strap the walls internally.

Photos show what I did today

 

[noseall]

I am underpinning my bay window. I dug out the first section today and got down to the brick spread foundation. I am down 650mm to the top of the brick spread foundation.

Do I now need to go under this foundation or could I just clean up what I’ve done and add the concrete.. the bay has pulled away from the main wall hence I am strengthening the foundation and then I will strap the walls internally.

Photos show what I did today

The idea of underpinning is that you dig wholly under the masonry and fill with concrete. It's a thankless task and one which I now, do not put my hand up to do.

 

[trevorbayliss]

Ok, thanks Noseall. It was pretty easy going doing this today. About 40 mins. To get down and under I will prob have to make the whole area bigger. Do you know roughly how deep I will need to go below the current foundation ? Am I looking at going the same depth again ? So another 600mm ?Or just till I hit clay. It is a clay area where I am.

 

[stevie888]

Little point in going deeper than the main founds otherwise your bay will sit still while the rest of the structure moves

 

[ree]

OP,
You need to bring in a SE esp. with the presence of a clay site.
IME, common causes of bay movement are Differential Settlement or a failing Bressumer Beam.
There are other causes eg. leaking drains - cellars -trees.
Safe Remedial work can sometimes be complicated.