Image Map

Sunday, August 11, 2013

DIY Concrete Edger or Retaining Curb

During our backyard remodel project last year, one of the biggest projects we took on was creating a concrete curb to surround our play structure. We were going to be adding 6 inches of playground mulch to the area (in the hopes it would keep our crazy son from breaking anything). But, before we could load up that area with mulch we needed something to contain it.

Enter: the curb idea. It was so simple at first. "Hey! Why don't we put in a concrete curb like you see at the park! That way we can make it into any shape we want!". Poor, dumb people.

Professional curb installers use what is called a "curb extruding machine". Sadly, no where around these parts rents one. This left us to figure out how to do it on our own.

4x8 Hardboard: Have the people at Home Depot or Lowes cut it into 6" (or whatever height you want your curb to be) lengths.  You get 8-8' pieces out of each 4x8 sheet.  You need enough to go the length of the curb times two.
Concrete (27 bags at around $2.70 a piece)
Concrete mixer ($25 rental)
Wooden stakes
Screws (any kind will do)
4x8 OSB: cut to size for spacers ($8)
Pam cooking spray
Flat head shovel
Concrete curber
Concrete scorer
Concrete float
Garden hose
Several helping hands: we did it with 4 people, but 5 would have been nice

Overall cost of project (with borrowed tools): around $125

First you want to mark out your border. The easiest way to do this is to lay an old garden hose on the ground and shape it until you are happy with how it looks. I would advise to keep your curves large and smooth. Avoid sharp turns, as the hardboard may crack when forced into extreme angles.

Next, take a flat shovel and begin smoothing out the area, following the shape of your garden hose. Once you have smoothed out the shape clearly with the shovel, move the hose and go over it one more time with the shovel.

Next hammer a few wooden stakes along the perimeter of your shape.

Depending upon how wide you would like your curb, cut a block of wood to use as a spacer. This will be the block of wood you wedge in between the front and back board as you go along, ensuring the curb is uniform throughout. In our case, our curb was 4 inches wide and 6 inches tall. So our spacer was 6" tall and 4" wide.

Attach your hardboard to your steaks using screws. Make sure you place your spacers as you go along. We would adjust the position of our steaks and hardboards to ensure a snug fit with our spacers.

Once you have your curb outlined with steaks and hardboard, with spacers placed throughout,it's time to bust out the Pam. That kitchen helper isn't just for pans you know. Spray the inside of your form generously with pam. This will ensure the forms separate from the curb cleanly. Now you can begin the concrete process.

We rented a cement mixer from home depot, and with the help of a friend with a truck we brought it and 27 bags of concrete mix home.

Trent began mixing the concrete following the directions on the bag. This was how he spent hours of his day. Once a batch of concrete was mixed, we dumped it into a wheelbarrow and trucked it over the the edger.

We had to work fast as it was another hot day (which is everyday between March and November) and the concrete was setting fast.

We shoveled concrete into the forms one small section at a time. As we poured in the concrete we would remove the spacers.
Using a concrete float, first I stabbed down into the concrete to release air bubbles, then I smoothed the top until there was a nice sheen of water. Then we would pour the next section and repeat.

If you want the curb to have nice rounded edges, you can purchase a concrete edger. Once the concrete is partially set (doesn't look shiny wet), you run it along the edges and it creates the smooth edge you see in professional curbs.

At this point you should lightly brush the top with a broom to create a texture.  This gives the concrete a more pleasant appeal, and creates a non slip surface.  Since the kiddos would be playing on the curb, this was very important.

Make sure that every two feet you score your curb. This means creating a line indentation along the top. When dry, concrete wants to crack. It needs to crack as part of the settling process. Creating score marks gives the curb a place for pressure to be released and crack if it needs to.

Keep your forms on and concrete wet according to your concrete bag instructions. For us, we watered it multiple times a day for 48 hrs. This allowed it to cure nice and strong before we took off the forms.

 Right after we removed the forms.

Look! A concrete playground edger!!

After all that hard work, when the weed cloth was laid and the mulch poured in, it was worth it!



It was an all day project, and it sure left us sore the next day. But in the end we had a nice safe place for the kids to play. Worth it.


  1. nice pictures and commentary Megan...

  2. Did it really take 27 bags of concrete? I want to do a similar project, but my area is maybe 2-3 times longer than yours. That's a lotta bags! Maybe I'll make mine thinner/shorter.

  3. Yes it really did take that many bags! We had to have the mulch a specific depth because it was a safety feature for our jungle gym, but if you aren't using it for that purpose then of course you could adjust the height and thickness. There's a multitude of concrete calculators out there to give you a general idea of how many bags you would need, but I'd suggest getting at least 10 additional bags then you think is necessary. It's much easier to return bags then it is to try and rush to the store in the final stretch with the concrete drying!

  4. You wrote "Once you have your curb outlined with steaks and hardboard". Were they T-bone or Ribeye steaks? You neglected to say how/where you cooked them. (or did you really mean stakes like at the beginning of your post?)
    How much of the mulch comes into the house when he is done playing? I remember building my kids a sandbox and we were always cleaning up the sand.

    1. Well since you're using steaks to secure the hardboard down, make sure they're T-bone and cooked to char. It's not very cost efficient but it really smells great. Slice them into triangle shapes prior to cooking because once they're bricks you can hammer them into the ground with the anger of the hulk. Make sure that you scream with each mallet blow.

      The mulch falls right off the kids, the only issue we've had is them putting it into buckets and sharing it into the yard/random places like my toolbox. The mulch pieces are much larger then sand and naturally fall off themselves

  5. Wow, I can't believe you guys did that in one day! I could imagine you were sore for a week after! It looks very nice and safe! I do not know if I would have the patience to do it myself!

  6. Thank you for the great post. I was looking for some guidance to do something very similar myself. Your post is the best thing I came across.

  7. How has the curb held up as far as cracking? I am considering the same project and I am gathering all the info I can get. Could you send a current close up photo?