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]