The Brew Cabin

Posted: **Thu Jun 21, 2018 12:23 pm**

Hi all,

Been browsing the website for a while now but things with my house renovation are beginning to crack on and "unknowns" are staring to arise so thought i'd sign up.

As per the title, I am looking to shortly start digging out a 6m by 6m chunk of my sloping front garden to form a driveway. The existing garden is rather steep and I would need retaining walls on two sides (garage is on the other side). Weighing up costs and ease of myself and a friend doing it all DIY (with digger etc for soil excavation etc), I have concluded that horizontal rail way sleepers slotted between 152x152x23 steels is a reasonable solution.

The wall will need to be between 1500 - 1800mm high maximum. The wall will be over 5m away from the house. The soil behind the wall will be clay and I am fully aware of the need to allow for drainage behind the wall etc etc.

My question regards the depths of the steels below ground that will be buried in concrete. From reading I seem to have deduced that the steels should be the same height in the ground as they are out the ground (1500 - 1800) and that the holes for the steels should be roughly 450mm in diameter. Can anyone give any guidance on this please? I acknowledge the forces applied to retaining walls and its important to me that the wall is suitable however 15-1800 does seem pretty significant.

Any advice appreciated. Thanks.

Posted: **Fri Jun 22, 2018 3:34 am**

only a structural engineer can advise you on this and they wont advise you to make a timber retaining wall
I hear you on cost overuns though
2 big issues here are the steel rusting and the timber rotting
you would be far better doing a wide flattish footing say 900 wide and 300mm deep of concrete and using H blocks and filling them with concrete then back up with shingle and drain etc
the thing you described with sleepers and steels and steels is what we use for storing manure and leaf mould at the allotments :;):
cheers
LLL

Posted: **Fri Jun 22, 2018 8:19 am**

With LLL on this. Structural engineer must be on board. Maybe stepoc blocks are good for retaining walls.

Posted: **Mon Jul 02, 2018 12:11 pm**

Hi there, thanks for the comments.

Just thought I'd do an update on this. Out of chance, I managed to speak to an experienced Structural Engineer I met through work last week and discussed my conundrum in passing conversation. The engineer quite confidently said that if he was building a wall for his own purposes then he would use a steel depth beneath the ground that matched that sticking above it and that would be more than enough. If however he was advising a client, and in order for him to hang his hat on his calcs for insurance purposes, he would advise the steel depth to be double the depth of the height of the wall.

My decision i guess!

The Brew Cabin

Railway sleeper & rsj retaining wall query