Retaining Wall Questions

[Rich Riddle]

I am looking at installing a retaining wall system about three feet above grade. Do you folks recommend a segmented block system or a poured concrete system? I know little to nothing about the segmented blocks or who makes a superior product. Any information or links you can provide will be appreciated.

[Don Morris]

I used 6" x 6" pressure treated pine (which you can get at the local big box store) to create a retaining wall system on a portion of the hill which forms my backyard. I drilled holes through the logs and used Rebar to form them into a 3' tall wall. On the side of the house, which is still on the slope of the hill, there is an air conditioner and a heat pump within a couple feet of each other. To accommodate for the drop in elevation the HVAC people used the same PT pine system (did they get the idea from me or I from them) to form a 1' wall. The neighbor across the street has his backyard at the opposite end of the slope as is mine. His backyard ends with a 4' or 5' wall of PT pine emptying onto an open field. It's late at night or I'd take a photo and include it, but if you really want, in daytime, I'll take a couple and send them, if you're really interested. I thought about cement, but it cracks over time and I didn't want to go that route. This seemed more user friendly and the hardest part was transportation. I thought the esthetics was a little better too. And this system, at least in my community, is commonly used as a retaining wall. That may be because of HOA laws, if you have to pass inspection.

[Bryan Rocker]

When I was younger, I used to build retaining walls out of railroad ties. The boss would go buy them for 5 bucks or so and we unload them and sort them. They last a dam long time. They were the ones removed from service from the railroads. As long as you canted them back a bit and staked them well they will hold most anything back as long as you don't go to high, 3' isn't to much, maybe 5 rows high at most. I think you can still pick them up for $8-10 a piece at the local BORG. We would cut them with chainsaws, did dull the blades after a few cuts, usually from hidden rocks, and toe nailed them with 12" galvanized nails and treated 2x4 driven in behind. Now days I would secure them with exterior grade screws for a stronger hold and maybe drop a post hole or two behind the wall to anchor the wall with.

Good luck with it, young backs are they way to go regardless of how you do it......its not for us old farts.

Bryanf

[Fred Perreault]

Around here we build low-medium height retaining walls out of native rocks or wood timbers more often than with concrete or blocks. Each has it's own merits. Rocks would cost more than anything else, and are usually bigger than 1-2 men can handle and place. However, rocks last a long time, and can be used as a planting bed, for ivy, etc. There are numerous wood options, all of varying quality and life span. One can stack them up nearly vertically, based on finished height, if you use a timber section as a "dead man" anchor every so often. These would be 4'-6' pieces that are spaced along the wall and extend back from the wall into the excavated area that will be fackfilled. The weight of the backfill, coupled with the frequency of the dead men versus height, will hold the wall in place for the life of the wall. We use pressure treated timbers where space or economy are a concern. We use 10" Timberloc fasteners to tie the timbers together....they are fast and easy with a strong electric drill/driver. A 3' timber wall could be built up by one person quite readily, and if other platforms or such were needed nearby, it would be easy fastening to wood.

[Rich Riddle]

For the application we are considering the options have been narrowed to ether a concrete retaining wall or segmented block retaining wall. There is a segmented block retaining wall near the location where the new wall will be located. This wall will more-or-less be unseen on the front side. On top of this retaining wall we are placing a patio area for the pool. At the current time a deck is located where the wall/patio will be located. When it gets sufficient light outside, I will post a picture so you understand why the choices of materials have been limited. Thanks.

[David Weaver]

I've got walls on either side of my driveway (that basically goes into my basement level). They are block. I'd suggest block solely because depending on where you're putting them, they may move before the blocks are bad (they will soften a little over the years, but not too much too fast), and when they do that, fixing the situation is free other than your labor.

[Stephen Musial]

Definitely block over poured concrete. With block, you go down so one course is buried and then build the wall up a course at a time. Put a 4" drain line and landscape cloth behind it, backfill with landscape cloth and cover the last couple of rows with dirt (after bringing the landscape cloth over the top so the dirt doesn't filter into the stone). With this system, there's no hydrostatic pressure to speak of which is why it doesn't need to be engineered.

With concrete, you'll have to have an engineer design the footing and steel schedule, pour the footing then pour the wall - big bucks compared to modular blocks.

Depending upon your municipality, you may not even have to get a permit for a modular wall if it's below 3 or 4 feet tall.

[Joe Tilson]

Rich,
Broken up sidewalk does a good job, as well as block or even better, and it looks like natural rock when finished. After replacing two wooden walls twice each we finally went with segmented block in the front of the house, and in back we used the sidewalks the city was digging up in front of the house to build a retaining wall in the back of the house. If I could get pictures on this blog from windows gallery, I would post them for you. Alas, so far this cannot be done. Timbers lasting thirty years from big box stores is a joke. Suggest you use stone, old concrete, or block filled with concrete. Good luck.

[Joe Tilson]

Rich, Send me a pm as I am coming up your way Wednesday and will be crossing Black Mt. on my way to Lynch. I would like to meet some of my fellow bloggers, if possible.
Thanks, Joe

[Rick Potter]

You might check with your building department. They should have a handout showing what is recommended. There are requirements in many places for foundation, rebar, etc. In my case, I installed a 3' high, segmented block wall, and later removed it, and put it block. For me the segmented block took up too much space and was always messy. A normal cement block wall will outlast your kids.

The block wall behind my house is 16' tall, miles long, and has a foundation 6-8' deep, with large key, courtesy of the highway which is my back yard.

Rick Potter

[Lee Schierer]

One thing to remember about any retaining wall is that you need to deal with water coming up behind the wall. You must drain away this water or the wall will fail sooner than later. In areas where you see freezing temperatures, this failure can occur after the first winter depending upon how much water there is and how cold it gets.

[Von Bickley]

I would use the landscape stones. In the past, I have used railroad ties, landscape timbers, and PT lumber. In the area where I live, if wood is in contact with dirt, it is an invitation for fire ants.

I would go with the stone and a good construction adhesive.

[Bruce Page]

I installed a segmented block wall 10-12 years ago that has been rock solid. They weigh 40# each and have fiberglass pins between the layers to keep them from moving. I bought them from a local masonry yard.

[Rich Riddle]

Well here are the pictures so you know the job. The deck in these photographs goes away when the retaining wall is built. Instead of another deck, we will use pavers. We want to evict the skunk and mink families living under the deck. They are friendly with us, but we don't want to push their tolerance of us or the dogs.

Here is the wall running perpendicular to the one that will be built. If the walls are the letter T this would be the vertical component of the T while the one being built will be the horizontal member of the T. The new wall will be entirely below the existing one. A close-up reveals that this wall started to sag this winter. There is also a slight dip in the concrete that just occurred on the patio. That will likely get mud jacked back in place. The wall will be dismantled and a new base laid on the portion that needs repair.
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Here is the hill after removing honeysuckle and running it through the shredder. It's a lot of time to shred this much honeysuckle. We live at the top of this very steep hill. Only the very edge will be retained and before the steep decline. The wall will most likely correlate to the current deck boundaries. This does give an idea of how steep the hill rapidly gets.

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Only the far edge of the property has the hill failing. The rest of the supports have remained stable and straight as seen in this photograph.

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Here you can see the far edge of the property line where the deck support is sliding. This is the only deck support on the entire forty foot run that is bent and failing. Despite that, the retaining wall will span the entire length of the old deck and then even some toward the opposite property line where a retaining wall was built by the former owner. You can also see the edge of the other retaining wall that slightly bent.You can also see the rather large column that weighs six tons (literally). That column sits on a pad that is four feet deep and three feet in diameter, steel reinforced and 5000 psi concrete. It hasn't budged.
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A close-up of the tilted support for the deck.

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[Rich Riddle]

I am having some problems loading other photographs but will load them when capable.

[Brian Elfert]

Landscape timbers don't last worth a darn. You'll be lucky to get over ten years based on my parent's experience. They have been in their house 30 years and the landscape timbers need replacement for a third time. They installed a fairly large block retaining wall at least five years ago and the only problem has been that it has dropped an inch or so.