Tieing in old & new foundations

[jassdhali]

Guys,
I know am I asking a load of questions but have more one please.
Dug my strip foundation for porch ( No building regs required) against the corner of my house 600mm and 1m deep.
The old house foundations stops at 800mm.
Question is what is the best way to tie new and old together, shall I just dig further down and under old foundations so that they sit on new foundations? and If so by how much..
Thanks again

 

[handyman77]

Do not undermine your existing foundations. Just dig down for your new foundations. You shouldnt leave the soil under the existing foundations uncovered for a long period of time because the soil/clay can shrink causing some damage. Not really anything to worry bout as your only exposing a small section( i think). Just a cautionary note.

 

[^woody^]

You don't tie new foundations in to the existing ones and dont do under them either

 

[jassdhali]

Cheers guys,

I will cover the foundation back up, handyman - was only a small section.
Thanks