use a post hole borer to dig 300mm diameter holes so that the total depth is as deep as the wall is high. angle the borer to allow for the slope of the poles 1:10 so the posts lean 100mm for every 1m of height . place about 100mm of drainage metal scoria in the holes and then put the two end posts in place.
retaining wall base trench dig a base trench 24 in. 600 mm wide the length of the wall.** the depth of the trench will be 6 in. 150 mm plus an additional 1 in. 25 mm for each 1 ft 300 mm of wall height for the amount or buried block that is needed.**
for example if your wall is going to be 800mm high, the holes for your posts should be 500mm deep. time now to concrete your posts into position. sleeper retaining wall posts come in two varieties steel galvanised h beams or a vertical sleepers. using sleepers as your posts costs about a third of the price of h beams.
how to build a timber retaining wall. wall height; round or square posts this will determine post spacing and hole depth. measure the height of the hole from top to bottom which also represents how deep the hole is. assume that the height or depth for your hole is 10 cms.
build a retaining wall. construction how-to, landscaping january 2, because theres so much post buried in the earth, a wall like this is solid state and resists moving, even if the soil on the hill youre holding back is mobile. we dug 30 4-foot deep holes in one long day with this machine, including all the bucket work.
to make a retaining wall the stone or other immutable material must be make a 45-degree angle into the hillside. the footing must be as broad as the plinth and must go as deep as the frost line. in new england where i live the frost line is 4 feet deep, so i have used that depth in the diagram.