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keyser soze 03-17-2008 11:37 AM

Going to build a retaining wall. Want to run my idea by you guys and gals
We have a slope that we'd like to put a wall in front of. I want to use steel I beams and PT 4x6's like they do on the sides of the interstate (at least they do around here). I would be laying the 4x6's flat so that they are 6" deep, 4" high and 5' long. The original plan was to use the locking blocks but it looks like anything over 30" needs to be reinforced which sounds like more work than the I beam wall.

I'm planning on using 6" beams with a 4" flange. I was going to bury 2/3 of what is above ground and cement the beams into the ground before I start dropping the lumber in place. That is to say that 3' above ground would have 2' below ground for a 5' total beam. Does this sound way off? Overkill is fine, that's how I do things so if this is just barely enough I'll go 50/50.

I see that in most places a 4' or higher wall needs to be engineered but this wall isn't being built in "most places". It's actually in a large campground and this wall will be by far the strongest wall in the place. Some existing ones are made of railroad ties and are 15-20 feet tall!

It will only be 5' at it's highest anyway (most of it at about 4'). The back fill would only be about 18-24 inches deep at the top and the bank is existing dirt that has been freestanding. We will use gravel for the back fill.

Thanks a lot for any help you can provide. I know it's a odd question but I thought some of you experts could help.

concretemasonry 03-17-2008 12:12 PM

Going to build a retaining wall. Want to run my idea by you guys and gals
If you are limited to 30" for height, you were looking at the wrong system or the person selling it is ignorant!!

Take a look at the sites for the different Segmental Retaining Wall (SRW) systems - Allan Block, Anchor Wall Systems, Keystone and Versalok. None of these use steel reinforcement, but some higher walls and different may require geo-grid mesh for anchorage or to reinforce the soil behind the wall.

They all have great applications, instructions, details and design tables for the different size products they each make. - Most have 3 or 4 different size and shape units. With engineering, the heights can go up to 45 feet.

keyser soze 03-17-2008 12:28 PM


I was googling around and that was the only site I found... Shoulda googled harder I suppose. I don't call stores to ask about this kind of stuff anymore. I'm off to check out the names you provided. Thanks a million.

You think the SRW will be easier to build than the I beams and 4x6's? I know it will be prettier, that's for sure but almost no one will see it since a camper will be in front of it. I guess it comes down to cost. I think we can get the I beam version up in 3 days or less, the block may cost less but take more time or vice versa. Plus I assume we'd need to lay a foundation to keep it from settling. That's no biggie since my buddy knows concrete.

I'll go do some research before I ask anything else.

Thanks again CM. :thumbup:

concretemasonry 03-17-2008 12:57 PM

You never put a segmental retaining wall on a concrete footing. You usually place the first course on a gravel or stone base about a foot deep. - The states, counties and all municipalites do it all the time because the walls work better without a concrete footing.

The sites mentioned earlier have the installation standards and suggestions.

tigerbalm2424 03-17-2008 01:20 PM

Heres the one I completed:

I dont have final pics posted but its three tiers around the house with the highest about 5-6 feet. The geo-grid or "engineering" is pretty inexpensive and is simple to install. If you want to over-engineer the wall just put down a roll of geogrid after every three courses of block.

The geo-grid is just the black mesh that you see on the last 3-4 pircutres laying over the blocks.

keyser soze 03-17-2008 05:33 PM

Oh, OK CM, thanks. I was wondering why they never mentioned it on the sites... Now I know. I thought it might settle in places and start to look bad but I guess not. I'll bury the bottom course fully and maybe the bottom edge of the second course as well. It will be about 11 courses at the very highest and only for the width of a few blocks it tapers down on both sides so the geogrid sounds like a good idea. When the word engineering was mentioned I pictured a structural or mechanical engineer needing to be hired (which sounds expensive to me). They just mean to use geogrid? Please forgive me if I'm misunderstanding this.

I'll have to look into this geogrid some more, I don't quite understand it's purpose on first look but I'm sure it won't be hard to find info about. I didn't have time this afternoon to do as much research as I'd like so I'm still a little in the dark.

Turns out that the SRW blocks are approx the same cost as I beams and 4x6s. That's the good news. The bad news is that we need almost 350 blocks. At least we don't need as many as you did tiger. Whew!

Thanks guys. I really appreciate the help. I promise not to ask any more stupid questions until I research this for a few more hours.

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