retaining wall footing

I have an area under the house about 2.7m high, the plans are for a future room under neath. I will need to put a retaining wall around three sides, only 900 high.

Could I put the footing on top of the soil or does it have to be dug. I was thinking of boxing it up on the level thats there. I could dig into the soil bank which is about 1.5m high so the footing is keyed in. I dont like the idea of digging thats all.

Im sure the weight of the concrete and double brick would be ample. The bank holds itself almost vertical and the only cave ins have been from water run off when we've had big rains otherwise its dry. I will put appropriate drains behind and aggregate.

See below diagram to what i had in mind

I’d be inclined to place the footings under the purposed floor level. Mainly because these places usually have a habit of becoming water traps and if you use blocks for the retaining wall you can build in engaged piers to take bearers if you go timber or trimdeck as the formwork if you go concrete.

What ever you do, water will always be a hassle and you’ll need to paint the retaining wall with tar and cover it with plastic membrane then sheets of fibro cement and the put in Agricultural Pipe coved with gravel so the pipe stays clean so if water does get down there it has some where to run.
I'd go with something along this line, I'm not an engineer, this is just a rough idea what I would do.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p>




Good luck with that you'll need it!

anymore thoughts

Dan574, what ever you do dig the base into the ground, because as you said you have had a water problem in the past and if the ground behind the wall becomes wet it expands, especially so if its clay, and puts tremendous pressure on the wall. If the base is above ground or floor level it will just push the wall out of alignment at best, at worst it may push over the house supports shown in your sketch. Along with the reinforcement shown in Auspiciousdna's sketch and filling the blocks with concrete where the rods are, as well as adequate drainage you will have a retaining wall that will outlast you.

thanks the only problem is that Im well below the natural level and its all mud rock so digging will be a *****

You project going terribly wrong would be a costly %$^@,
what would be the better option, just a %$^@ or a costly %$^@.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p>

Hard work is less likely to kill you, than stress!

Hire yourself a Kanga hammer and go for it, your body will benefit after the initial soreness