need help with retaining wall project!!

[Mr. Potato Head]

Hello,

This weekend warrior needs to build a 40 foot by 3 feet high retaining wall. After that, I'm going to build terraces toward the back of my patio to hold back a dirt hill.

chose Keystone's Legacy stone because I can get it at Home Depot, it's cheap and they'll deliver many palettes of this stuff for $65. RCP block wanted $800 to deliver four palettes--the choice was easy. Also, the stones lock in place and don't have to use anything else other than to stack them on top of each other. I've never worked with concrete so I don't even want to get into that *yet*.

My questions are:

1. How deep does the foundation of the wall have to be? I'd hate the thought of making a four inch trench with a sand base, and then burrying attractive (expensive) rock to support the wall. Can't I use dirt filled cinder blocks, would that support the wall? Please folks, keep in mind that I've never done this before so I appologize if that's a stupid question.

1. The large stones are heavy (50lbs). I can stack them but I'd be doing it myself. My wife wants to help--is looking forward to it--but they're too heavy for her. What do contractors use ( that you don't have to rent) to lift these monsters around?

2. What's the rule of thumb for using small stones versus large stones. I'm considering using the small stones simply because they're lighter. Why would I want to use larger stones?

Thanks

- Alex.

[RicodJour]

Generally for a low wall like yours the first course is buried. You will complicate your life if you try to save money with concrete block.

Hands. The wife can be in charge of backfilling and filter fabric.

Heavy stone provides more mass which provides more strength - you can go higher with the wall with larger, heavier stones.

The manufacturer's installation guides available on their web site will spell all of this stuff out for you.

R

[jeffc]

How are you going to attach the Keystone stone to the cinder block? The point of that stuff is you don't have to do any mortaring or anything.

[Jonny]

Recipe for disaster. Sand can washout, either immediately, or over time. Use a combination rock and gravel base. Pour a 4" deep slab on top of that. Backfill the slab with gravel/rock combination on the lower side of the incline. First course of cinder block with concrete fill. I would recommend putting a drainage slot every 3rd cinder block, no mortar between, if you had mortared joints above that first row. Cover the backfill with soil and sod when done.

Am assuming you're referring to this below as this is the only one weighing in at 50 pounds each.

would choose a structural stone used later in the webpage that you provided as you may get hydraulic bulging with loose laid stone.

Larger units used in building mean less overall work and time usage, assuming of course the workmen can lift/carry/manipulate these larger units. There is less chance of mistakes in joints and rows as there are less joints and rows. Cinder block vs. brick as an example. Smaller/shorter units give you more options for height and length without cutting.

[Nightrider.36]

Ok, good point--as I said, I've never done this before so there's a bunch of things I haven't solved yet. Scratch the cinder block idea.

It just seems wasteful to bury that nice, $4 rock. There has to be an inexpensive solution that does not involve mixing concrete.

Also, the guy at Home Depot who teaches a class there said that I would probably not need drainage because of where I live and because it's only going to be a 3 foot wall. The soil around my place is pretty shoaly--gravelly? ( I don't know if that's a word ). He said that I can put gravel, and drainage in but I'd be doing something that mother nature's already done.

I'll gladly spend the money on something that I know is going to benefit this project in the long run. I just want to also take advantage of money saving measures if I can without hurting the overall outcome. There's a fine balance and I need to find it.

Thanks all.

[DanG]

I disagree about pouring concrete under the decorative walls. They are designed to flex with the ground. It is always easiest to terrace the hillside, build a short wall, step back into the hill, another short wall. Holding back large vertical lifts requires heavier block and deadman tie backs.

The key to any of the decorative walls is getting water through the walls and not holding moisture. The most important thing is getting gravel under the wall and behind it, ideally protected by geotextile cloth to prevent blocking the gravel drain with dirt. The "garden wall" blocks are the easiest to use, but are limited to 2' tall walls. There are full technical design and installation directions at the Keystone site:

go to the site map at the top right of the page. You will find the answers to most all your questions. They have complete installation directions available, same place.

Great looking walls when done right. We have done several that have been in place for over ten years with no problems. You need to decide whether you want the walls to run on true horizontal or follow the ground. All that I have done have run on true level which may require slightly more block in some circumstances. The full Keystone blocks weigh about 100 pounds and they require 2 men. Depending on how close you can get the pallets or skid steer/backhoe/whatever makes a lot of difference. ______________________________ Keep the whole world singing . . . . DanG (remove the sevens) [e-mail]

[Nightrider.36]

Thanks Dan, I'm not going to use concrete. But I think that may have been the answer I received because I considered using cinder blocks as the first course. I didn't want to have to bury decorative rock as it's expensive. But, I guess that's the way it goes.

I'm going to stick to the directions on the keystone website and even call them if I have any questions.

Thanks to all, you've been very helpful.

- Alex

[RicodJour]

Doing the stuff you don't see the right way is just as important as the stuff you do see. You're not throwing money away. It's a system, each individual block is not that expensive, and whatever cost-saving attempt would most likely result in an inferior wall and more labor.

R

[jeffc]

It's easy and cheap considering alternatives.

The drainage for these things is built in if you don't mortar. Water just seeps through the joints between your stones.