This section will explain how to make a garden retaining wall along an existing fence, which can transform a dull front or back yard into an exciting garden. The retaining wall will be 1 meter (40″) in from the fence and on average 400mm (16″) high (depending on the contour of the ground), and with a Covering A piece of sawn, or dressed lumber of greater width than thickness. Usually 19mm (3/4") to 38mm (1 1/2") thick and 75mm (3") or more wide. on top will also double for a seat the length of the retaining wall.
The drawing above shows an example of the shape the retaining wall might take, but other shapes and ideas are only limited by the imagination.
The posts will be spaced a maximum of 1200mm (4ft) and concreted into see PILE holes 500mm (20″) deep.
Capping: Treated 150×50 rough-sawn.
Step 1: Determine perimeters
Determine the shape and perimeters of the retaining wall and mark out with a string line slightly above ground and tied to stakes where needed. The string line will mark the outside boundary of the retaining wall.
Step 2: Preparing holes
Mark out all end and corner post holes first. External corners will have 2 posts and internal corners will have 1 post (see drawing below)
Dig all the post holes 250mm (10″) diameter and 500mm (20″) deep.
Note: If the ground is exceptionally soft or subject to frosts, then the hole should be deeper and the diameter larger. Commonsense stuff.
Step 3: Putting in the posts
Cut all the posts 1 meter (40″) long. That is slightly longer than required, but the tops will be trimmed later.
Make a mix of A mixture of sand, gravel, water and cement which hardens to a stone like condition when dry..
In a wheelbarrow or concrete mixer make a mix consisting of 5 parts aggregate (gravel and sand), to one part A powdery type substance made from a mixture of earths materials such as limestone and shale, which is sintered (cause to become solid mass by heating without melting), ground, and mixed with small amounts of calcium sulphate and calcium carbonate. Cement is activated by water and when mixed with gravel and sand, forms concrete..
Pour in clean water and mix to a uniform consistency with a spade or shovel.
The mix should be stiff enough to hold up the posts without the need of bracing props yet wet enough to work around the posts
Put the corner and end posts in first. Position the posts to almost touching the string line and ensure post is Vertical; Upright. or Plumb, upright. by way of holding a Tool used to ensure surfaces are level or plumb by means of a bubble in a tube of liquid fitted to the level. against two adjacent sides of the post.
Shovel concrete around the post and fill to within 50mm (2″) from the top of the hole.
Lift the post up slightly in order to allow some concrete to flow under the post. Shake the post repeatedly slightly back and forward (having a vibrating effect) to enable the concrete to flow evenly under and around the post. You shake it to the left you shake it to the right you do the hippy shake and you shake it all about…
Check the post again for position and plum.
Repeat this action until all posts are in. First the corner and end posts and then the intermediate posts.
Leave a couple of days to How much the teeth are angled out on a circular saw blade..
Step 4: Fixing the retaining boards
The posts should be approximately 550mm (22″) out of the ground. That is more than needed, but the tops will be trimmed off later.
The retaining boards are 150×50 (2×6) treated rough-sawn Any of the framing wood., and the required finished height of the wall including the capping is 400mm (16″) which is a good seat height, but of course the height will vary in places due to the contour of the ground.
To obtain the required height, the first (bottom) board needs to be 80mm (3″) above ground level. Achieve this by either ripping (cutting) along the board or by digging the board into the ground. To secure with nails or screws. the first board level to the inside of the posts with 100mm (4″) Covered with a protective coating of zinc. nails. Join boards only on posts.
Fix another two boards on top of the first.
If the ground is not even, it will be necessary to either step up or step down the retaining wall depending on the contour of the ground.
Do this as shown in drawing below.
Step 5: Trimming the posts and fixing the capping
With a handsaw, The finish materials in a building, such as narrow boards applied around openings (window trim, door trim) and vertical corner battens. the top of the posts off level and Being even with. with the top of the retaining boards.
Fix the capping on it’s flat so it covers both retaining board and post. Miter corners and rises and fix to both retaining boards and posts with 100mm (4″) galvanized flathead nails.
Step 6: Fixing the retaining boards to the fence
Fix the top retaining board to the fence posts with 100mm (4″) galvanized nails so it is level with the top of the retaining wall capping
Fix the second board under the first and A short nail with a large flat head used for securing roofing felt, plasterboard, sheet metal to wood etc. also to the fence posts.
The third board (bottom) can be placed on the ground and against the second board. It does not have to be ripped (cut) or dug into the ground. The loose fit is good for water seepage.
Fence posts are not purpose designed as retaining wall posts, so a To make rigid. is required to The part of the plywood wall panels that overlaps the door and window frame, and protrudes into the door or window area and covers any gaps between the door/window and the surrounding frame. It acts as a stop for the door and also stops the rain getting in. the fence from leaning or being forced out when the soil is placed in the retained area.
Brace each post as shown in the drawing below using 75×50 (2×3) treated lumber for both braces and pegs (A cut lengthwise along a board that also runs with the grain. (As opposed to cross-cut.) 150×50 (2×6) retaining board in half to get the braces and pegs. A metal rod that has a head on one end and threads on the other and is used to fasten together lumber. The most common bolts used or referred to in projects within this website are coach/carriage bolts and hex bolts. the braces to both the fence posts and the pegs using galvanized bolts or galvanized Are round headed bolts with square shoulders that resist rotation when located or driven into place. They can be called coach bolts or carriage bolts depending on which part of the world you live in. The head end of the bolt does not need a washer, but the other end of the bolt (the nut end) usually does. screws.
Step 7: Drainage and fill
This retaining wall retains little soil and not subject to the forces of higher walls, however, a drainage system is still advisable to take seepage away and to avoid any possible waterlogging.
Position old sheets of cardboard, hardboard or gibboard (or some other material that will disintegrate) down the back, about 100mm (4″) behind the retaining wall.
Commence filling the retaining area up. Fill between the sheets and the wall with drainage metal and behind with soil, keeping the level the same on both sides of the sheets.
If there are gaps between the retaining boards, that will be enough to let the seepage through and complete the drainage system.
If there are no gaps between the retaining boards, either drill weep holes in the bottom retaining board about every 1200mm (4ft) or run a drain coil or drain tile the length of the wall at the bottom of the drainage metal backfill.