Retaining Wall

[gamecoder.nz]

Hi everyone,

I'm building a timber retaining wall around the edge of my layout and two of the corners are angled like this but I'm not sure how I would go about building them

 

[GAP]

Cut the diagonal board longer than the 2 side boards so it overlaps them.
Sit it on top of the 2 side boards mark the angle then cut the side board ends at the angle.
Drop the angle board down and mark the length using the side boards as a guide for the angle, then trim it.
When all boards are trimmed drive some "batten" screws board into the upright posts to secure them.
You can also drive some "batten" screws through the angle board into the side boards to give extra strength.
Use batten crews about 30% longer than the timber to make sure you go all the way through and get a good purchase in the upright posts.
Dig the uprights at least 300mm into the ground and use rapid set concrete to stop them moving. The hole depth depend on how high you ares going with the wall.

 

[maxi-model]

My instincts would be to use the boards at the sides as a means of retaining the board in the centre. I.E. your centre board is cut long at the back tapering to a narrower front with the side boards "clasping", so to speak, this center board. Certainly use, as stout as practical, support posts cemented into the ground with "postcreate". The facing boards need to be pretty thick as earth, even on level ground will compress and cause these to bulge if not thick enough. My local garden works specialist spec'ed 4" thick stained oak "sleepers" for my retaining walls and 3" square support posts. Screw fixings same as sugggested by GAP. My walls though meet at 90° or are free standing at one end. They have been up 10 years and not failed yet. Some old concrete sloped paths, capping debris and hardcore, were removed to create the flat and permeable, 20mm green granite surfaced, area in front. Retaining walls are 30" tall. Max

Basic works before track laying. Note "rice crispy" pads put in to level and support points & crossings

90° Butt jointed corner. Note cossing beam that supports one side of turning triangle (Y)

Free standing end, this part just has free standing waste concrete "rocks" acting as capping.

View out the kitchen window now. Those little trees and plants have grown. The little folk have moved in and built a town too

 

[Gerard]

Hello Gamecoder,

This is how you make a proper foundation for an earth retaining structure:
First some soil mechanics explanation:
1 The stability of a slope depends on the slope angle.
2 Normal sand and/or loose material has a natural angle of repose of about 30 degrees.
3 So when you trying to build a wall of sandy material the slope will be maximal about 30 degrees.
4 This means that when building a vertical retaining wall using concrete slabs or alike you have to put anchors on long horizontal steel double wires in the soil so the reach behind that 30 degree stability line.

You can make simple cheap and durable anchors from concrete slabs but you must use strong anchor wires made from stainless/galvanized steel so they can withstand time.
When there is no soil slope allready available then start building layer by layer the 30 degree slope and put the concrete anchors beyond the 30 degree line.
In case the sand layer is allready there and is not completely dry and loose but a bit moisty, it will have some clay like extra shear properties , meaning you can build a more steep wall as long as it does not dry out. In that case you can dig out narrow cuts for the wires and the anchors.

After placing the anchors and wires you first must fill in the cuts for the wires and anchors and compact the infill.
Then bring tension on the anchor waires by turn around the wire.
Now fill the space behind the retaining wall and do the compaction and if necessary bring more tension in the anchor wires in order to keep the retaining wall vertical upright.