Browse Forums Landscape & Garden Design 1 May 16, 2011 4:50 pm Hey all, I've got to build a few retaining walls for our new house (when I say "I", I mean pay someone to do it!). A bit of research and I'm as confused as when I started about the difference between the longevity and suitability of treated pine vs hardwood. Some say one, some say the other. The highest wall we need is 800mm tapering to 200mm, most of the others are 600 -> 200. The natural soil type (according to our soil report is Gravelly Clayey Sand, but there is also fill described as Gravelly Silty Clay. Assuming they are laid correctly, with appropriate drainage, at the correct angle, etc. would do the masses suggest as being the victor in this battle? Cheers, Maz Re: Timber Retaining Walls -Treated pine or hardwood? 2May 16, 2011 6:25 pm Hi, What is your budget? Hardwood is more expensive than treated pine. Have you considered other materials such as Concrete Sleepers, rendered Besser block, Sandstone, or the various dry-stack block systems that are available. There is more to walls than just timber, be it hardwood or treated pine. Food for thought. Rgds Leonard. Re: Timber Retaining Walls -Treated pine or hardwood? 3May 16, 2011 8:29 pm Its an expense we didn't plan on, so the cheaper the better. Another issue is the horizontal space they take up - all of the walls we need done now are pretty close to the house. I'm planning on doing some dry stack walls out the front post-handover, but i can't do that in this initial instance. Can't stand the look of the concrete walls... Re: Timber Retaining Walls -Treated pine or hardwood? 4May 16, 2011 9:02 pm I think you may have answered your own question. Mazisto Its an expense we didn't plan on, so the cheaper the better. Re: Timber Retaining Walls -Treated pine or hardwood? 5May 16, 2011 9:11 pm I think we were looking at walls of a similar height to yours. While I was keen on the dry stack blocks (going by looks) someone told me the weight of the water might push the blocks forward, so we may just go with treated pine. Just my thoughts. Now: Building another new home Settlement: 8 July 2021 Construction due to start: In two months Re: Timber Retaining Walls -Treated pine or hardwood? 6May 16, 2011 9:18 pm I'm guessing to make it cheap if someone else is doing it then Galvanized posts (100UC) with treated pine sleepers is the way to go. The gal posts are expensive but there is less labour involved and an 800mm wall is going to need alot more labour if done with wood posts. That being the case I don't think you'd bother with hardwood sleepers as IMO they are worthwhile only if you were building with wooden posts and wanted a better appearance and less chance of warping/twisting that pine can have. BTW the gal posts are pretty ugly but I've seen some people actually paint them along with the sleepers all in one color and it can look reasonable. Re: Timber Retaining Walls -Treated pine or hardwood? 7May 16, 2011 9:59 pm karmaz I think we were looking at walls of a similar height to yours. While I was keen on the dry stack blocks (going by looks) someone told me the weight of the water might push the blocks forward, so we may just go with treated pine. Just my thoughts. Sorry to hijack this thread. I promise only one off topic post. In most cases it is poor drainage behind the wall that causes a wall to fail. If the water cannot get out then it has to go somewhere so it just sits in the earth behind the wall. The more water added = the more pressure in the sodden earth and it begins swell and push, and easiest way for it is to go forward. This applies to any materials used to construct a wall not just dry stack. Hope this helps in you decision on what type of wall you end up choosing. Rgds Leonard. Re: Timber Retaining Walls -Treated pine or hardwood? 8May 16, 2011 10:41 pm I have stacked volcanic rock, cheap but heavy work. Looks great, very little prep needed, no drainage issues. Just stack the rocks to required height like its been done for centuries. I think the professional term is "rock armouring". Re: Timber Retaining Walls -Treated pine or hardwood? 9May 17, 2011 11:20 am KnockItDown karmaz I think we were looking at walls of a similar height to yours. While I was keen on the dry stack blocks (going by looks) someone told me the weight of the water might push the blocks forward, so we may just go with treated pine. Just my thoughts. Sorry to hijack this thread. I promise only one off topic post. In most cases it is poor drainage behind the wall that causes a wall to fail. If the water cannot get out then it has to go somewhere so it just sits in the earth behind the wall. The more water added = the more pressure in the sodden earth and it begins swell and push, and easiest way for it is to go forward. This applies to any materials used to construct a wall not just dry stack. Hope this helps in you decision on what type of wall you end up choosing. Rgds Leonard. No it's all great information. Thanks everyone. I'm pretty sure that I'll go with treated pine. The installer says he uses ash + ag pipe, which seems to be what's mostly recommended. Re: Timber Retaining Walls -Treated pine or hardwood? 10May 20, 2011 10:08 pm O.K. your in Brisbane, there is no provision in the Queensland Timbers tech data sheet for treated pine at the height you mentioned( 1m) the highest you can go is 800mm with 1500mm centers on your posts (75mm) whoever is installing your wall should be following these span tables. Hi All. I'm currently resurfacing the hardwood floors and when removing the old layers that there's a long dark line running across the boards. 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