How to build a Treated Pine Retaining Wall

How to build a Treated Pine Retaining Wall
This is a guide only for building a wall up to 600mmH without using an
engineer or machinery. Any retaining wall over this height we suggest you
contact an engineer and check your local council requirements.
A treated pine retaining wall can be made from sleepers, round logs, or slabs.
The choice of round or flat is a personal choice. We recommend you use
round logs over sleepers for the posts as they are more durable.
Once you have chosen what style of pine
wall you are going to build measure the
length and height and drop into one of our
Gardenworld stores. We will work out how
much you require along with all the other
landscaping supplies you will need to do
the job.
Stake a wooden peg at one end of the wall to be constructed and another at
the other end. Tie a string line to this to enable you to keep your wall straight.
Measure along the string line and mark where you will need to put your vertical
posts or logs. How far apart you space the posts is dependent on the soil, the
load to be retained and the diameter size of the log. In saying that a general
rule of thumb is 1.2mt intervals if you are using 2.4mt H sleepers, or 1.5mt if
using 3mtH sleepers. If using 2.4mt logs cut them in half, so that you have the
required height of 1.2mt for a 600mm wall. (Make sure to seal any cut ends of
the timber)
You can hire a post hole borer, or use a Bobcat but
with a bit of hard work you can also dig the post holes
yourself. You need to dig about 650-750mm deep and
allow 400mm for width (500mm for 3mt posts)
381 Hillsborough Rd
Warners Bay 4954 6999
Fax: 4956 6826
72 Pacific Highway
2214 Pacific Highway
Ourimbah 4362 2822
Raymond Terrace 4987 2302
Fax: 4362 1190
Fax: 4983 1854
To email all stores: [email protected]
Place approximately 100mm of aggregate into the bottom of the hole for
drainage and place your post in. Aggregate can be bought in bulk by the
scoop from your local Gardenworld store. Fill the hole with concrete (sand,
cement & gravel or a pre-mixed bag) to the level of the ground. Lean posts
slightly (about 5 degrees) towards the bank. Work your way from the outside
posts in to the centre. Posts can be braced with a timber peg if necessary and
then left to set in the concrete for a day.
The first row of horizontal timber is the most important. It needs to be level.
Drill your hole slightly smaller than the galvanized nail or spike you are going
to use to secure the timber and place into position. Check with a level before
nailing. You can start at the top of the wall and build down, or the reverse,
making sure joints meet at a vertical post. If using logs angle them (see
diagram) to ensure an even surface.
Now it’s time to ensure you have your drainage correct. It will make all the
difference to the end result. Agricultural pipe needs to be laid behind the base
of the wall with aggregate spread on top to a level of about 100mm. The pipe
should extend past the wall and disperse to a drainage outlet.
You may use some Geotech fabric directly
behind the timber wall to help reduce any
soil colouration or leaking. (It is available
by the metre from Lee Rowan’s). Do not
use black plastic sheeting, as it will hold
the water instead of allowing it to disperse.
Backfill your wall with soil to just below ground level. If planting a garden at the
top of the wall try to use a good quality garden soil such as Lee’s Rich Organic
to give your plants the best start.
NB. This is a guide only, therefore no liability can be accepted by Lee Rowan’s
Gardenworld.
381 Hillsborough Rd
Warners Bay 4954 6999
Fax: 4956 6826
72 Pacific Highway
2214 Pacific Highway
Ourimbah 4362 2822
Raymond Terrace 4987 2302
Fax: 4362 1190
Fax: 4983 1854
To email all stores: [email protected]