Firstly, sorry if this has already been answered- i had a look but couldnt see anything so if i have missed it, please feel free to point me at it!
I have an old single garage at the bottom of my garden that leads to a road running perpendicular to it, parallel to the garden. The garden is level, but built into a hill ( house built in the mid 30's) so the road is higher than the garden meaning the garage was erected on top of a 1 metre high plinth. On the other side of the garden (so opposite the road) the garden is retained by a wall, which looks about 2 metres high (hard to judge when peering over the fence!) The existing structure has around 1 metre between it's end and the retaining wall. Now, the garage is really too small to use as such, so I would love to extend it/demolish/ whatever to end up with a double garage. Unfortunately, while the actual garage building doesn't worry me, I want to make sure that the new plinth will work properly so.... do I just design the strip foundations as though i was buiding a normal building, but 1 metre higher, build the first metre with thicker blocks then infill the first metre with broken bricks etc then the floor.... Or do i need to do something funky??? oh yeah i'd describe the sub soil as firm clay, there has been on movement of the retaining wall while the garage has been there (garage built in the sixties, you can tell the wall is original) there are no trees etc nearby and I was looking to build the walls from thermalite blocks.
Any advice would be greatly appreciated,
Thanks in advance