Eugene, an avid self-taught DIYer and engineer, has acquired almost 40 years of experience with power/hand tools, plumbing, and woodwork.
Giving Your Driveway a Crisp, Clean Look
Edging a lawn or driveway gives it it a crisp, clean look and helps the eye to define the boundary between grass, flower beds and the harder look of the concrete, stone or blacktop surface of your drive. There are lots of options including brick and cut stone, but in this article we look at an inexpensive method, using concrete edging stones. These are reasonably easy to install if you have basic DIY skills.
Tools Required for Laying Concrete Edging Kerbs
- Shovel for mixing concrete
- Cement Mixer (optional) for mixing concrete quicker and more thoroughly
- Level for checking edging is plumb
- String line and canes, bars, or pegs for supporting line
- Mallet or alternatively builder's hammer for tapping stones into place
- Kerb stones
- Ballast (mixed aggregate) or alternatively small stone and building sand
- Portland or flyash cement
As an alternative to making your own concrete, you can buy ready-made drymix.
Kerbs are supported by a bed of concrete on the underside and haunching or supporting concrete at the rear. Since most of the pressure will be from vehicles and human traffic on the driveway surface, this prevents the stones from being pushed backwards into flowerbeds or the lawn. You can also use concrete at the front for added support or back fill with stone.
I deal with 2 inch by 7 inch edging in this guide. Thicker kerbs with a wider base are normally used for a driveway, but in my case the stones are under bushes at the edge of the drive and unlikely to be driven on. You can also use thin edging stones like these as a trim on the boundary of a lawn.
Follow these steps to lay your stones
Step 1. Dig a trench
Dig a trench about 8" (200 mm) wide by 7" (175 mm) deep. A 2" to 3" (50 mm to 75 mm) bed of concrete is sufficient for laying light edging kerbs, so that allows 2" to 3" of the edging to project above the surface when placed on top of the bed. However you can adjust the depth of the trench to modify this.
Step 2. Place a Line the Length of the Trench
A string line acts as a guide for laying stones which are placed so that the back edge of a stone just touches the line along it's whole length. The line also acts as a height guide. You can make a line with a couple of iron bars, wooden stakes or similar and some string. Tie the string loosely onto each bar so that it can be moved up and down the bars when they're hammered into the ground, rather than pushing the bars in or out of the ground to adjust height.
- Push or hammer the first bar into the ground.
- If the trench is straight, pull the line tight and hammer the bar at the other end of the line into the ground.
- Adjust the height of the line at each end so that it's at the height you want your edging stones (2" to 3" above the surface). If the ground is sloped, usually you want the edging stones to follow the slope, so don't level the string.
- The string will sag along it's length just like a clothes line or electricity wires. So you need to support it every 6 feet or so with additional bars/pegs. Instead of tying these to the line, just twist the string around each bar. The easiest way to do this is by holding the bar horizontally and wrapping a single turn of string around it. Then twist the bar into a vertical position and push into the ground.
- By sighting along the entire length of the line, if necessary adjust the position of the bars from front to back of the trench so that they all line up.
- Again by sighting along the line, adjust string up or down on the intermediate pegs so that the line is straight along the full length and doesn't dip on any peg.
Step 3. Mix the Concrete for Bedding the Edging
Use a C20 general purpose mix which is 1 part cement to 4 parts stone and 2 parts sand. (These proportions are by volume not by weight). A single mix with a small cement mixer will produce about a wheel barrow full of concrete, sufficient to bed three, 3 foot long (approx 1 m) kerbs. Concrete should be mixed stiffly with as little water as possible so that it will support edging stones without being squeezed out from underneath. You can learn how to mix concrete using either of my two guides:
Step 4. Lay a Bed of Concrete
- Lay enough concrete in the trench to bed two or three stones and extend it just beyond where the last edging stone in this group will be placed. I've found a garden spade is the most convenient tool, but you can also use a brick laying trowel. As shown in the diagram below, concrete should extend backwards 2" to 4" beyond the the line and stones so that it acts as a base for the haunching and also extend a couple of inches forward into the trench. The depth of the bed should be about 2" to 3" (50 mm to 75 mm).
- A short piece of timber (e.g. 1 foot of 2 x 7) the same height as an edging stone, is useful for checking the bed is sufficiently deep. Allow 1/2" to 3/4" (12 to 18 mm) or so of concrete for sinking/ tapping a kerb into place. Therefore when the top edge of the timber is this distance above the string line, the bed is the correct depth.
- Smooth off the bed with a piece of timber or trowel to make it roughly level.
Step 4. Bed the Edging in the Concrete
- Lower a stone gently into place. If concrete is a bit on the soft side, plonking it into place can result in it sinking too much. Ensure it butts tightly up against stones previously laid. Align it so that the back of the stone lines up with the string line.
- Using a mallet or the end of the handle of a builder's hammer, tap evenly along the top surface of the stone to bed it into place so that the rear top edge is barely in contact with the line. This can be a bit tricky to judge with curved top edging stones, so use a level from the front, extending back to the line. The level should barely touch the line when a stone is sufficiently bedded down.
- If the stone is too low in the concrete bed, lift it back out and add concrete in the low spots. If your mix is too wet, concrete can squeeze out from under a stone, so allow a little extra time for it to stiffen and pull it back into place.
- Check the vertical face of the stone is plumb using your level and adjust as necessary.
- If you intend to lay further stones later after concrete has set, smooth and taper the bed of concrete that extends beyond the last stone downwards so that it doesn't obstruct laying the next stone.
Step 7. Add Support at the Front and Back
I found that using blobs of concrete at the front and back at each joint helps to keep stones in place until haunching is placed at the back. A pointing trowel is small and useful for doing this. Press the blobs tightly against the stones to give a buttress effect. Continue to lay stones, adding blobs of concrete at each joint.
Step 8. Place the Haunching Concrete
- Once concrete is sufficiently stiff, place haunching concrete at the back along the full length of edging. Use a spade, shovel or if the space is narrow, a trowel.
- In general, haunching should extend at least half way up the back of a stone but you can finish it 1" to 2" (25 mm to 50 mm) below the top edge. The width of the haunching bed should be at least the width of an edging stone. (For my edging project the stones were 2" wide, but I made the haunching bed 4" wide).
- Pack the haunching with a piece of 2 inch board. You can slope it slightly to aid water run off.
- Most pressure will come from the front of a driveway as vehicles push gravel downwards and outwards to the side. So haunching is necessary to prevent edging stones from moving backwards relative to each other. You can also add haunching at the front. I just used three blobs per stone, extending up to about 3" below the top of a stone and then back filled in front of the stones with a mixture of sand and small gravel. I can't guarantee this is adequate though, so you can haunch along the full length of stones with concrete to be totally certain they won't move. Front haunching doesn't need to extend up the stones as far as at the back, a couple of inches being adequate.
Bed and Haunching Dimensions
At least half height of stone minium, but ideally up to 2" (50 mm) below top edge of stone
At least width of stone, but ideally about 4" (100 mm)
2" to 3" (50 mm to 75 mm)
Haunch width + width of stone + 2" to 3" (50 mm to 75 mm) in front of stone
My kerbs are 2" above the level of my drive. In retrospect maybe I should have raised them an inch or so higher to prevent soil in the raised flower beds from spreading over them if there's any movement over time or I get a new layer of gravel for the driveway.
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
© 2020 Eugene Brennan
Danny from India on October 20, 2020:
Helpful tips, need to try at my place.
Eugene Brennan (author) from Ireland on October 19, 2020:
Audrey Hunt from Idyllwild Ca. on October 19, 2020:
Thanks for this tutorial. Helpful photos.