Browse Forums Landscape & Garden Design Re: Retaining wall 3Jan 06, 2012 8:43 am that's what I thought. Thanks for your help. But now I'm thinking what thickness to do the wall? Since it's only 400mm high at it's highest point. I'm tossing up between: 200 x 75 x 3000 treated pine 200 x 100 x 3000 treated pine I'm not sure if I need that extra thickness?? Re: Retaining wall 4Jan 06, 2012 9:25 am At 400 high, I would use 200 x 50 x 3000, with maybe an extra post in it. I made a wall 800 high using 50mm sleepers, that was 2+ years ago, only supporting fill/garden and it hasn't moved an inch and sunk the posts about 6-800 where we could, had to use a jackhammer so we went as deep as we could through the rock or till we got sick of hammering.... Re: Retaining wall 5Jan 06, 2012 7:42 pm I used 200 x 75 treated pine on 1200 centres for my posts and 2400 x 200 x 50 for my wall panels. Gal Coach bolts secure it all together. Have a look at some pics on my landscaping thread. (Page 2 onwards) viewtopic.php?f=19&t=44663 Re: Retaining wall 6Jan 10, 2012 9:26 am Here is the guide on how to do it and what to use ot make it structurally sound: http://www.jimboombatimbers.com.au/Retaining%20Walls.pdf The question is what will be the spacing between the posts. @ 1200mm use 150x50mm posts in 400mm deep and 150x50mm wales (the sleepers) @ 2400mm use 200x100mm posts in 400mm deep and 200x100mm wales (the sleepers) Building a Plantation Emperor Q1 at Spring Mountain Estate, Greenbank SE QLD Re: Retaining wall 7Jan 10, 2012 10:20 am kodaz @ 1200mm use 150x50mm posts in 400mm deep and 150x50mm wales (the sleepers) @ 2400mm use 200x100mm posts in 400mm deep and 200x100mm wales (the sleepers) Got to disagree with those post sizes. If using timber for posts I would use no less than 200mmx100mm posts at any span. Also please don't use 50mm for anything more that single height sleepers and even then they will warp. OP, 200mm X 75mm X 3000m will be fine if you have 1500mm post centres. This should mean you have little to no warping in the sleepers. Re: Retaining wall 8Jan 10, 2012 10:24 am Then I suggest you take that up with Timber Queensland. They have undoubtedly made the above attached data sheet to cover them with enough over engineering to ensure they don't get sued if the walls fall down. And when you think their job is to ensure more wood is sold I doubt they have scrimped on timber sizing. But who am I to argue, your credentials will stand on their own. Building a Plantation Emperor Q1 at Spring Mountain Estate, Greenbank SE QLD Re: Retaining wall 9Jan 10, 2012 4:35 pm chrisandkate Also please don't use 50mm for anything more that single height sleepers and even then they will warp. OP, 200mm X 75mm X 3000m will be fine if you have 1500mm post centres. This should mean you have little to no warping in the sleepers. My wall tends to disagree. 200, 50, 2400 with 1200 posts at offset joins, 3 and 4 high has not warped at all, and it has been 2 or more years now I can't remember. Re: Retaining wall 10Jan 11, 2012 5:51 pm Chrisandkate is spot on with sizings of timber although you could use a 75mmx200mm upright and it wont fail at 400mm high if you have non to low reactive soil ( and not holding up the neighbours house), if you can afford it use Galv. h and c sections, they do look a bit industrial though. dont forget a min. 200mm beam of non expansive aggregate drainage behind wall with a slotted aggy pipe. And dont use black plastic to line it you will get major negative hydrostatic pressure build up and the wall could fail. I use core flute as a timber protectant when needed. Da Vinci Outdoor Living Architectural landscaping http://www.davincioutdoor.com Re: Retaining wall 11Jan 12, 2012 10:55 am I'm pretty sure the only people responsible for any failure of a wall are the people who build it or an engineer who specifies and product/unit/size that is later found to be inappropriate. It may be a case of the person chose the incorrect size also. Timber Queensland can release as many data sheets as they like but they will in no way take responsibility for the the final installed product regardless of who built or specified it. Testing under controlled conditions only gives an example of what products are capable of and there are many other factors to take into account that vary in each case. As for 50mm sleepers warping or not. I have seen many warp and many not. I prefer to live on the cautious side in these cases. I have an old retaining wall at my place that has 200mm X 100mm posts and 200mm X 75mm sleepers. Granted it is over 1mt high and its hardwood so will be able to take more load, but I would not feel comfortable in using posts that are the same size as the sleepers unless the sleepers were in fact way over sized. I have no qualification in engineering/building/other (in fact no qualifications at all if it makes a difference to anyone, but I doubt that) but this has been a focus of mine recently during our build and I would hate to see someone have to rebuild a wall in a few years where a little bit of info I have gained could have helped. Good luck with you project OP. Regards Chris Thank you again Simeon.. I will call my certifier for that. Have a good day 4 5188 Thanks for the insights, that makes perfect sense, and yeah, I will be leaning on the experience of the excavator operator entirely. 6 16147 Hi All, I engaged a tradie to install concrete retaining wall 600-800mm high over 32 meters in Victoria. Sleepers are 200*75*2000 mm installed over 17 steel posts. I… 0 6917 |