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retaining wall on a budget

Posted by festucablue 5 (My Page) on
Tue, Jun 3, 08 at 23:37

I would appreciate any suggestions on what materials to use to build a 12 foot long, 4 foot high retaining wall, using cheaper materials: pressure treated wood is expensive ... rocks are too heavy and it would take too long to gather ... what else can I use? Also, I cannot use any concrete, town regulations for the area.

Thanks.


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RE: retaining wall on a budget

  • Posted by laag z6CapeCod (My Page) on
    Wed, Jun 4, 08 at 6:50

If it is cheap and it works, you'll see it a lot.

Usually, there is a lot more to a retaining wall than what you see. There is a lot of pressure behind a 4' wall. Whatever you use to hold back that 4' has to be able to more than match that force.

There are two basic retaining wall types used on residential property for the most part - a "gravity wall" and a "cantelever wall".

A gravity wall uses mass to counteract the force of what is being retained. You can look at it as being heavier than the force being applied to it. Modular block retaining wall systems, dry stone walls, and pressure treated tie wals are all variations of a "gravity wall".

Pressure treated ties use cribbing or deadmen to tie some of the backfill of the wall to the wall in order to add mass to the wall (it is not to anchor the ties as many believe).

Modular blocks have a certain amount of mass to them by just being heavy. Often they are designed to be filled with gravel to further add mass to them to stand up to more pressure. When that is not enough, a material called "geogrid is used to tie the mass of some of the backfill to the blocks.

A dry stone wall uses the mass of the stone.

A cantelevered wall works like a chair. If you walk up to an empty chair, you can easily push it over backward fairly easily. Put a fat guy in the chair and it does not roll over so easily. A cantelevered wall is often made of poured concrete or "cinder blocks" (cmu - concrete masonry unit) tied to a poured concrete footing with steel rebar. What we see is the face of the wall. What we don't see is that there is a wide footing that extends fron a few inches in front of the wall to sometimes several feet behind the wall to form an "L". The backfill sits on the bottom of the "L" like the fat guy in the chair which keeps the vertical part of the "L" from toppling.

Don't make the mistake that, if you cover the face of a cut or fill with a strong material, it will be an effective retaining wall.

The cheapest way to build a strong safe 4' retaining wall in my area is to use an excavator to line up large boulders like a sea wall. The mass of the boulders is enough.


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RE: retaining wall on a budget

tires, don't know how attractive it will be though, but my landscaping friend says when done well, they'll never budge. I guess you could always grow ivy or something similar on it.


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RE: retaining wall on a budget

  • Posted by laag z6CapeCod (My Page) on
    Wed, Jun 4, 08 at 21:20

I've taken apart tire walls. Don't do it!


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RE: retaining wall on a budget

Ok, I have used treated 8x8 to build a retaining wall for my parking area. It is approx 3' high and 16' long. It cost around $700 total. I used rebar, 10" galvinized spikes, and a 2 foot 1/2 drill bit. I also had to purchase a chain saw to cut them with (included in the price). I did all the work myself about 4 years. The wall has not moved one bit.

I believe that I spent a low price for what I have done. If you're doing the work yourself, it isn't hard. It would have been nice to have someone help lift the lumber with me. But I did it all on my own. I really don't think you are going to find a cheaper material than the landscaping ties. I looked into stone blocks as an alternative and the cost was too high.


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RE: retaining wall on a budget

Thank you for the replies.
laag, what an informative comment, and it's true, I always thought the deadmen were supposed to create leverage. I am suprised though to hear that hiring a landscaper to dig and lay bolders would be a cheap propostion, but I'll look into it.
drexel, your suggestion is what I initially planned to do, untill I got a quote of $2,500 to $3,000, including materials. Well, that is definitely above my budget, as doing it myself is above my stamina level. Good for you though!

So, this is why I thought to ask for a cheaper option. I always imagine there must be an innovative, out of the box solution, but I guess a retaining wall is not something to experiment with. I am getting a quote tomorrow from an outfit using keystones, but I don't expect it to be cheaper then wood.


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RE: retaining wall on a budget

  • Posted by laag z6CapeCod (My Page) on
    Fri, Jun 6, 08 at 7:05

That is a very high quote for a PT tie wall of that size unless there is an unusual circumstance or additional work.

I would expect to pay $1,800 - $2,500 for the Keystone and under $2k for timber, but prices and availability of qualified contractors varies from place to place.


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RE: retaining wall on a budget

I disagree- that bid doesn't seem out of line. 6"x8"x8' p/t timbers are what we use for walls and they're not cheap. By the time you factor in the materials & markup (timbers, spikes, backfill), the time to stock the job, the time on site, access issues, and the cleanup... it sounds like maybe you got a quote from someone who understands the business and isn't bidding off a blind SF price. That's a good thing, potentially.

Unfortunately, retaining walls involve three expensive elements: time, materials, and liability.


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RE: retaining wall on a budget

  • Posted by laag z6CapeCod (My Page) on
    Fri, Jun 6, 08 at 13:12

Unless there is an unusual circumstance, a "square foot" price works. The shorter the length of wall, the less prep time there is. Twelve feet is not a lot of base prep.. That is a tie and a half or 9 Keystone blocks. Fifty bucks a face foot is a lot of dough for a PT tie wall of that length.

If there is more work than that, it is not the price of the wall that is being talked about. $3k might not be much for a job that includes a 48 FF tie wall, but it is high for just the tie wall.


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RE: retaining wall on a budget

When I see what others have to pay, it sure makes me glad I live where it's warm, Arkansas. No freezing ground to worry with. No red tape, permits or inspections in my little town.

Here is a 28 ft by 4 ft high section of my DIY concrete walls, cost under $500 back when concrete was $72 a yard.

Photobucket


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RE: retaining wall on a budget

PT Timber is the cheapest temporary retaining wall. You'll be re-building in 10-15 years. Small retaining concrete blocks are under $2 per 4x12 blocks.
I've run into literature on a green retaining wall. Geotextile bags are filled with soil and stacked like blocks. Within weeks vegetation grows through the bags as they form a pretty strong retaining wall. I've seen very high walls built using this method nearly vertical walls.


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