I'm at the start of a landscaping project where I want to build an 8m x 50cm retaining wall with a 90 degree turn followed by a further 7m x 50cm wall along the edge of a patio and retaining a gradual lawn increase which will be levelled out to approx 4m back. As I only want a 50 cm wall I thought about laying the 250x125 sleepers on their narrow side two high but am not sure if I need them to be supported from behind due to the weight of soil (or it is better to go for the broadest side)? And if so by rebar or posts? I considered cutting the slabs and putting the sleepers onto the already settled base of sand and gravel but this was stumped by two grids which would sit under the sleepers so may have to cut into the garden instead. The problem with this is that there is garden drainage going across the 8m length just in front of the patio which the beams would sit on. The drainage pipe was laid about a foot underneath a layer of aggregate which was then topped with turf and I am not sure if the weight of the sleepers will crush the pipe? Assuming I am ok to lay the sleepers on top of the aggregate I then need to create a foundation for the 7m length which is only half patio and half garden at the moment. I've done lots of research which varies from it being fine to lay straight onto the soil, laying a loose pea shingle base 15cm deep by 30cm wide or laying a course of concrete. Out of the three options the shingle would be my choice but would this be ok with the dimensions and weight? I've attached a picture with the design and am aware I will also need to create a foundation for the sleepers which make up the steps. Thanks in advance Chris
If your plans are to have the fencing as per your drawing, you could set the fence posts into the ground a couple of feet, as you should, then you could attach the sleepers to posts from behind.
Yeah. I thought about doubling up and using the fence posts as the retaining posts but the other half wants them sat on top of the sleepers not recessed I would have put a counter argument together if it weren't for the drainage. If I need to put posts in they will need to be set in a concrete base at least a foot down which is about the depth of the drain
Hi Shaggy. Whether the sleepers are on their ends or flat, what will hold them vertical and stop them moving under the slow-but-relentless force of the raised garden? Sis is going to have to do something a bit similar - build a retaining wall to hold back next door's garden which is a good metre high. The plan is to use sleepers as posts every 1.2m spacing or so into the ground by 2.5' and then slip additional sleepers on their edges (actually 8x2s as they'll still look like sleepers from the front... ) down behind them to act as the wall. Ie - there will be solid posts to hold back the garden. What are you planning to use to hold your sleepers in place?
I did this in my son's garden a couple of years ago and it was very effective. I too got excellent advice from the members of this forum (thanks again). I had a stepped wall, that allowed long bench seating along his patio. This has proved very effective. Steve
With the relatively low height, the butting upto the lipped edge of the patio slabs, weight and timberlock screws if I went with the non-post method I hadn't planned on having anything else to hold back the pressure. I've seen 2400x200x100 with low delivery ata reasonable price and adjusted my design to have the broadside down and stack them 5 high instead. Each 2400 weighs 30kg. Is the combined weight going to be a problem for the drain and is it ok to use aggregate as the sole base for this weight?
Aw, Jit - how can we get on with important forum stuff with all the endless Simpsons vids to watch... Anyhoo, here's Homer being Mr Ha...:
Thinking of going with a 150mm deep 300mm wide course of loose pea shingle with a 150mm bed of sharp sand to sit the sleepers on their broadest (200mm) side. I've read about piling 6mm rebars in but will this be pointless driving them into gravel?
Forget the sand, it will just wash away through the gravel anyway. Just sit them on 100mm of gravel for drainage. If your not going to fit any form of fixing into the ground, then span the sleepers over each other like a brick bond, and join them together behind with treated timber supports at 1 metre intervals.
Fair enough. So no rebars and no sand - check. I'd already planned on interlocking the beams and joining them with 150mm timberfix screws (one at each end and one in the middle). I've read about deadmen - is this over kill for the small gradient? Do I actually need anything to stop it being pushed forward given the situation?
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