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How to Build a Stackable Block Retaining Wall
By: Julie Day 
Stackable stone walls create a nice border and increase lawn or garden space.
Retaining walls can be a great way not only to help with erosion and water drainage, but also to create beautiful, usable garden space. And thanks to interlocking, stackable blocks, the project can be completed in a weekend. Building a retaining wall is a tough job, but it’s something most homeowners can handle, as long as you’re able to do some heavy lifting and are willing to get dirty. Here’s what you need to know to build your own stackable retaining wall.
Stackable blocks come in many styles and colors.
Stackable Concrete Blocks
Stackable stones are made of concrete, with a decorative finish on the front and a lip on the back. The lip fits snugly against the block below it, creating an interlocking joint that holds up to pressure, while the decorative front gives an attractive finish. The stones are often slightly wedge-shaped to allow you to create gentle curves. With many styles, thin “topper” stones are also available, to give the wall a finished appearance.
Building Tip
Stackable stones are generally recommended for walls less than 3’- 4’ high. Taller walls typically need additional structural reinforcement and may require a building permit along with professional advice or help.
Low retaining walls can also be used to create pleasing curved lines.
Materials Needed
For this project, you will need:
- Work gloves
- Shovel and/or mattock
- Brick chisel and small sledgehammer
- Level
- Wooden stakes
- String and a line level
- Soil tamper
- Gravel (sharp, not rounded) or rock dust
- Landscape fabric (optional)
- Interlocking stackable stones and toppers
Estimating the number of blocks you’ll need is tough. Count on at least one block per linear foot, and count on it taking more blocks than your estimate suggests!
Stackable stones interlock to create a strong joint with a stepped-back effect.
Layout and Planning
- Before you begin, check with your city utilities office, or dial 811 to make sure there aren’t any buried pipes or cables in your digging zone.
- Use a garden hose to lay out a pleasing line for your retaining wall. Mark the ground using flour layout lines or landscape marking paint.
A properly leveled and tamped-down trench is important for building a strong wall.
Digging the Trench
- Along your marked line, carefully dig a trench slightly wider than the blocks (ideally, the width of your soil tamper), and deep enough so the first course of blocks is below ground level. Cut straight down with the shovel keep from disturbing the surrounding soil.
Building Tip
The pressure put on your wall will be tremendous. Putting the first course of stones below ground level will give the wall something solid to press against.
- Make the trench as level as you can, to save time later.
- If your wall goes across a slope, you can dig a series of stepped trenches so that only one course of blocks is below ground.
- Tamp down the bottom of the trench using a soil tamper.
- Add several inches of sharp gravel or rock dust to the bottom of the trench, and use this layer to do your final leveling and tamping.
Burying the first course of stones keeps the wall from sliding or moving.
Laying the First Course
- Start at the edge of the wall that’s most visible, or the edge that butts up against another structure. If your wall goes across a slope, start at the lowest end.
- Position the first stone in your trench. Make sure the stone is level from front to back and side to side. Adjust by lifting the stone and adding more gravel or digging deeper as necessary.
- Hammer wooden stakes in the ground at each end of the trench, and stretch a string between them even with the top of the first stone. Level the string with a line level, and use the string as a guide for laying the rest of the first course.
- Continue laying stones side-by-side along your trench, making sure they are level. Getting the first course right is the key to a successful wall.
The first course goes in carefully with the help of levels and a string guide.
Laying Additional Courses
- Each row of blocks is offset from the one below it. If your wall has straight edges on the ends, start your next course with a block that has been cut in half.
Building Tip
To cut a block in two, score a line around the middle with a brick chisel, then position the chisel on your scored line, and strike it with the small sledgehammer.
- If you’ve worked hard to make sure everything is level, then this is the fun part. Continue laying courses of stones, making sure the lip of the stone is tight against the stone below it, and also making sure the seams are offset. The front edge will have a slightly “stepped-back” look due to the lips on the stones.
- Periodically check to make sure the stones are level and wobble free.
- Build up the wall to the desired height, and top with topper stones if desired.
Topper stones add a finished look.
Cross-section view
Backfilling
- To keep your wall clean, spread landscape fabric up against the wall before backfilling.
- Backfill the area behind the wall in layers, with gravel against the wall and fill dirt behind it, firmly tamping down each layer.
- Finish with a layer of topsoil.
Building Tip
If your wall is intended to divert water runoff, place a perforated drain pipe against the back of the wall before backfilling.
This wall is stepped up to fit the contours of the slope.
Further Information
- Retaining Walls (Video)
- Types of Retaining Walls for Your Yard (video)
- How to Cut and Install Retaining Wall Topper Stones (article)
- How to Build Retaining Wall Corners (article)
- How to Align Blocks in a Curved Retaining Wall (article)
- White Efflorescence Stains on Retaining Walls (article)
- Building Retaining Wall (PaverSearch)
Please Leave a Comment
29 Comments on “How to Build a Stackable Block Retaining Wall”
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June 2nd, 2009 at 1:38 pm
I have a question. I did a a small retaining wall that I use blocks last year and now I see that they are turning or they age getting white. When I wet them down the blocks look great but when they dry out I see the white again. Is there something I can do to make them look like they do when they are wet? I don’t like to see the white that I am seeing. Can you help me?
June 15th, 2009 at 12:33 pm
Hi steve, i am in the process of building a retaining wall, and am prepared to guess that your wall is made of concrete blocks. If this is so, the white stuff s simply efflorescence. As far as I know, this is just a side effect of the concrete curing and aging. This website might have something to do about it :http://factsfacts.com/MyHomeRepair/efflorescence.htm
but i just skimmed it
Ben Erickson Says:June 17th, 2009 at 12:02 pm
Steve,
Your question about white stains on concrete walls has been answered by Julie Day on our website at White Efflorescence Stains on Retaining Walls.
September 28th, 2009 at 11:55 am
I need to create a low retention wall in a family community. What keeps the “vandals” (mostly kids 8-15yo)from simply disassembling this type of wall and what can I do structurally to prevent that?
Thanx.
October 14th, 2009 at 12:46 am
Patrik,
You could always use some masons adhesive which is easily applied using a caulk gun. That would prevent someone from vandalizing the wall and also provide additional stability.
May 27th, 2010 at 8:41 am
I would like to put a small retainer wall for my patio that is made like a figure 8. I want to know how hard is this project to complete?
May 28th, 2010 at 6:57 am
I am having a hard time finding a manufacturer of Stackable blocks you show on your web site at http://www.dannylipford.com/images/article/how-to-build-a-stackable-retaining-wall-8.jpg. I live in the Knoxville, TN. Any suggestions would be appreciated.
Julie Day Says:May 28th, 2010 at 9:26 am
Wayne, you can find stackable blocks at home improvement stores or landscape supply yards. The ones I used (in the next-to-last photo) are Pavestone Natural Impressions Flagstone from Home Depot.
Villia, stackable blocks work very well in curves. As you can see in the photos, the blocks are usually tapered to make moderate curves without needing to be cut. They’re a great choice for your patio! Any retaining wall is a hard project requires a lot of digging and heavy lifting, but a curved wall is really no harder than a straight one.
June 2nd, 2010 at 12:26 pm
I want to build about a 4 foot high retaining wall that will be straight is some spots but also with some curves. I live outside Anchorage. My concern is not earthquakes, but more dealing with the frost heave affects. Do you think the stackable block approach would work? Or do I need to use a foundation type approach?
Thanks
June 22nd, 2010 at 12:51 pm
What is a good way to cut the blocks, I have been using a circular saw with a carbon blade ( mason ) then knocking it with a chisel it seems to work ok ,but is there a more accurate way to do it ?
July 21st, 2010 at 11:16 am
I am building a retaining wall with stackable block. It is curved on one end and then straight for about 35 feet. The straight portion goes up a slope. The slope increases about 3′ from top to bottom therefore I have to step up as I proceed. Because of this and the fact that the blocks are stackable and have a 1/2 lip on the back of them, every time I step up the wall moves back 1/2 an inch. How do I get around this? It is preventing my wall from being straight.
July 29th, 2010 at 4:51 pm
Does anyone have more pictures of the Pavestone Natural Impressions Flagstone installed sold at Home Depot? I’m planning on installing them in two yards on a slight slope and would like to see how these were installed. Also looking at how to make turns to finish into top of slope, landscape fabric used behind pavers, what mason adhesive for caps, as well as any other tips.
Also curious if HD is flexible on their pricing if you buy a pallet vs by the block $2.58 a piece
Julie Day Says:August 3rd, 2010 at 8:44 am
Tom, I used the Natural Impressions pavers for my driveway retaining wall – I’ll send you a few more photos. They were easy to install – like other stackables, if you get the base nice and level, they just fit right into place.
I didn’t haggle over the price, but I should have – they’re more expensive (and smaller) than other styles of pavers!
Good luck!
August 4th, 2010 at 12:24 pm
Thanks… look forward to the pics.
August 17th, 2010 at 1:50 pm
What are “corded” stack blocks? I heard this term used at the local supply yard.
September 14th, 2010 at 8:56 pm
I am building a retaining wall up a slope with stackable blocks. The ground from the bottom to the top is about 6 feet with a length of 22 feet curving around the house. I am going to put in about 6 terraces to allow for the slope and am making each section about 12 inches high to allow for clearance with the siding on the house. I am having a hard time estimating the number of blocks that will be buried for each terrace going into the hillside. I am using grid paper and squares to scale 4″ by 12″. Is there any formula as to how many blocks you have to build into hillside?
September 17th, 2010 at 7:11 pm
Hi, I would like to build a small retaining wall on either side of my driveway around the concrete drainage pipe. Is there anything I should be aware of with this project, or is it just a straight forward retaining wall as stated here.
October 13th, 2010 at 12:24 pm
I am also attempting(for the first time) to put a retaining wall around the drainage pipe on either side of my drive way. I have started and stop a few times now becuase it doesn’t seem to look right. When I finally get it level at the very top there are open spaces in the areas where the blocks touch the pipe. I should say that once I get this wall completed( if ever) I will back fill with top soil and plant grass. Whtat do I fill the spaces with so if it rains the top soil won’t wash away. I am almost to the point of getting a contractor to do the job…lol. Thanx for your help
October 15th, 2010 at 10:09 am
I am putting a 10′ ring, three rows high, around a tree with blocks that have a tab in the back. The tab causes the circle of each row to be smaller than the one below. Should I space the bottom row of blocks 1/2″ apart and the second row 1/4″ apart so the top row fits snugly? Or what spacing would be better? Thank you.
October 23rd, 2010 at 9:07 pm
I want to extend my parking spot straight into a hillside, by about another 8′. Right now the left side is about 4′ high and sloped without any wall is and quite stable. The right side goes from 1/2′ to 4′ again without any wall and is stable. Once I get the area ahead of my car dug out, I’d like to have an open and staggered ( _-_-_-_ )cement block wall.. or treated 4×4′s and then block. Will I need a deadman into the slope ahead of my car spot if it’s as stable as the other areas? If so, how is it put in? The block retaining wall would have open spaces so I can plant flowers and to allow for any drainage. How steep or at what angle will I need to make the slope ahead when I’m digging it out? I hope eventually to build a lattice sided carport just to keep the weather off the car, I currently have two 4×4′s with lattice on either side as a wind break but can only pull my car in 1/2 way. Thank you for your input~!
October 26th, 2010 at 3:30 pm
Could we have a retaining wall of 15meter high using concrete block with cement/concrete inside?
October 30th, 2010 at 9:43 pm
I made a 10′ diameter circle 2 rows high, then capped. After i leveled 1st row, I started the second row with block centered over the seam of the lower. I thought it should stay centered over seam all the way around since they are all same size, but instead as it went around it gradually was off more and more and not centered over seam even though I am putting them end to end in an almost perfect circle. How or why did this happen?
Ben Erickson Says:October 31st, 2010 at 10:01 am
Hi Steve,
My guess is that the blocks you’re using are aligned when they lock together so each row is slightly stepped back from the one below, as are the rounded stones in the photo in the article above. That would result in each row having a bit smaller diameter circle than the one above it, and since the blocks are the same length, the cumulative effect would be that it would take fewer blocks to make a circle, throwing the joints off.
March 14th, 2011 at 2:17 pm
I have a retaining wall made with 4 x 4 cedar logs. It is pushing out. Can I replace it with stacking bricks? It is a straight wall.
March 23rd, 2011 at 2:57 pm
I am building a retaining wall that is 2 course high plus cap do i need two bury one? or can i go with one course plus cap?
April 6th, 2011 at 2:57 pm
I have a 1 foot retaining wall(wood) on the side of my driveway that needs replacing. Can I replace it with stacking blocks if they are to sit on top of my blacktop driveway?
July 6th, 2011 at 5:21 pm
I am building a 2 brick high “wall” around the base of my 15 foot round pool. The river rock comes out about 1 foot. I am going to use blocks that are advertised as being 3-1/2″Hx11-1/2″Wx7″D. How many blocks will I need to make a perfect circle?
August 14th, 2011 at 10:40 am
I just built a LARGE retaining wall (65′ x 7′); it was might first, and looks great. I researched on the internet how to do everything, and used over 40 tons of road gravel to backfill and compact as I built it.
I notice in the morning several rows (randomly) will have an inch or two of wet area across several blocks. sometimes this is near the bottom, other times this is in the fourth or fifth row. It varies to the right or left of the wall. This happens even when there has been no rain.
What is going on? Have I done something wrong?
November 21st, 2011 at 7:54 am
I am building a retaining wall with the larger block that have the lip on them. I am placing them on a flat concrete footer, do I start the first one with the lip up or down to get started level.