Allotment Gardening Advice Help Chat

Chatting => Design and Construction => Topic started by: maddave on June 16, 2020, 11:40

Title: Sleepers as a retaining wall, do they need support?
Post by: maddave on June 16, 2020, 11:40
I've been given a free greenhouse, so have been leveling the only bit of ground in the garden that gets the sun all day. It's currently a slope, so I have been digging out the soil, with a view of framing the area with sleepers (250 mm x 150 mm x 2.4 metres) laid long side up on the sub soil which is very compacted.  See attached drawing I've made.

The question is, do I need to support the sleepers with some kind of posts, or will the weight of the sleepers on top of each other stop them from toppling/leaning over?  I was looking at potentially using the following stakes, rather than having to use posts. Would these be enough?

Link here (https://www.indooroutdoors.co.uk/products/2-tier-straight-timber-railway-sleeper-driveway-path-pathway-edge-edging-bracket?variant=23419858951&currency=GBP&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&gclid=CjwKCAjw26H3BRB2EiwAy32zhSxSv0Iz9P86uqBie8Gr6VJ2l1fIB9RWI8JK0-EccVt1KfozWnRSXxoC0FMQAvD_BwE)

Edit to fix long link - Yorkie
Title: Re: Sleepers as a retaining wall, do they need support?
Post by: Yorkie on June 16, 2020, 21:52
I can't answer your specific question (any structural engineers around?), but the one general thing I think I know about retaining walls is that it's a good idea to have seep holes near the bottom to allow water to escape - otherwise the weight of soil can gather behind the wall and make it bulge.

May not be a problem with a low wall, though.
Title: Re: Sleepers as a retaining wall, do they need support?
Post by: snowdrops on June 17, 2020, 09:20
I’m not a structural engineer but what I know of sleepers is that you can buy specific bolts to anchor them together vertically so maybe they’re an option & perhaps some going through the bottom sleeper in to tge ground a goodly amount. If you are only going 2 high as in your diagram I would imagine you are not going to have the same issues as if you were trying to hold back 6ft of ground. A good landscape suppliers should know of the bolts I’ve mentioned, I know they were readily available when our son used them
Title: Re: Sleepers as a retaining wall, do they need support?
Post by: maddave on June 18, 2020, 09:19
Thanks for the replies. Yes, the wall isn't very high and it will be built up against earth which is already very compacted, rather than building a wall and shoveling new soil one side of it. I think I'll go for the stakes as they look quite substantial and then see if it wobbles!! If so I can add some more supports.
Title: Re: Sleepers as a retaining wall, do they need support?
Post by: jezza on June 26, 2020, 20:28
Hello the stakes you've shown look as if they'll work, I would personally put 40 inch steel  bars through the sleepers into the ground as extra Anchorage if that's not possible screw them together with specialist drill bolts (they have a small drill bit on the end)   jezza
Title: Re: Sleepers as a retaining wall, do they need support?
Post by: Aunt Sally on June 26, 2020, 23:35
I would personally put 40 inch steel  bars through the sleepers into the ground as extra Anchorage

Did you really mean 40 inches or is that a typo ?
Title: Re: Sleepers as a retaining wall, do they need support?
Post by: maddave on July 01, 2020, 10:59
For anyone interested, in the end I discarded the idea of sleepers. This was due to wanting long lengths rather than lots of short sleepers and a certain height, so the sleepers I was looking at were 2.8 metres long and 25 cm high.  They said they weighed 70KG each and with lockdown, only I was working on this, so would have struggled getting them round to the back garden and in place etc.  I decided to use long lengths of building joists, which are much lighter and manageable.  I also used fence posts to secure the sides after buying an auger drill bit on amazon which worked brilliantly at digging the post holes.  The sides are all in now and just need to get the base laid and then get the greenhouse at some point!!
Title: Re: Sleepers as a retaining wall, do they need support?
Post by: New shoot on July 01, 2020, 12:12
Looking good so far  :)