Concrete wall

[Nick]

I'm converting a large carport into a garage. The end away from the door has soil outside about 400mm above the floor, so I intend pouring a 700mm high concrete wall, 6 metres wide, starting 200mm below the floor, with a 200mm wide footing, and the rest of the wall 100mm thick. I will have a slotted drain pipe outside the wall. Later I will fill the whole floor with concrete.

I have plenty of reinforcing rod that I can put in the wall. How much should I use? And are those wall dimensions OK? The wall will not support anything except the soil and the plywood wall cladding. The ends of the wall will rest against two existing

150mm square treated poles that have 600mm square footings.

[The Natural Philosopher]

I'd save yourself some trouble and build it of concrete blocks tied together with ties EVERYWHERE..

Ive got a garden wall retaining about 10000 sq meters of 800mm deep soil and rubble. Its basically concrete block faced with brick - but that was for show. Two lines of block is fine. Only thing is to remove soil for about a foot or two upstream, and backfill with something looser than hard packed clay. And more permeable..otherwise you will have a water problem. In Germany I've seen them actually do cellars this way - go down deep, strip foundations, then a block wall, and run a DPM under the wall and up the outside, then 4" slabs of low density polystyrene to ground level, both for insulation and to protect against heave, back filled with gravel and a perf pipe, loose rubble and topsoil over.

Its fast and quick and the DPM keeps the water out, and the poly keeps the heave and the cold out.

If you like casting concrete, by all means use rods laced together and pour it, but do still use some poly outside...but I reckon blockwork is simpler and quicker for DIY.

[Nick]

Maybe, but I have already poured smaller walls around most of the carport. I have free builders' mix and boxing timber. I've almost finished the boxing. All I have to pay for is the cement. I have a concrete mixer. Next door there is a huge construction job going on. They may even have some concrete left over from their job :)

[meow2222]

8" is plenty thick enough to support 40cm of soil.

Adding 1% chopped plastic fibres would give you a tougher crete, though its not needed.

NT

[The Natural Philosopher]

If its all there, then go for it. Shove in some steel, and do think about a heave absorbing layer and DPM outside it though.