Contraction joints - Foundation contraction joints

[Chris101]

hi,
i am laying concrete footings for a low garden wall (650mm). the length is 25 metres. i have prepared the trench, which is mostly very sound, but there has been some slippage to the sides at one end. i am going to use wooden shuttering where the trench is less sound. does the timber need coating to rleease from the concrete? does the length of the footings mean i need to provide contraction joints. thanks

[lutonlagerlout]

architects and such love expansion joints but i am not a big fan,they look naff in walls
when you say 25 m long i suppose you could split the footing in to 2 or even 3 parts using 18 mm chipboard as a shutter, a lot depends on the ground as well, clay being bad for walls, while chalk is the best
btw if you hit nice chalk 225 mm deep is ok for a garden wall
regards tony