Building a rock wall

My side flower bed, which is adjacent to my gravel driveway, has a really ill-defined border and it looks like crap. My front lawn was torn up to put in a new septic system leach field, and there are tons of boulders of all shapes and sizes for the taking. Thought I might build me a rock wall around the flower bed. I already started by putting the first set down, which are flat rocks about a foot wide. It looks pretty cool, so I want to make it taller, maybe 6" high? The bed goes down a steepish slope, if that makes a difference.

Anyone ever do this? Do I need mortar, or can I just stack the rocks? If I don’t use mortar, will the winter undo the whole thing? Would I use regular old concrete mix, or is there something better for this job? I don’t want to spend a lot of money, since this is just a whimsical little (back breaking ) project I decided to do in the murderous heat of summer. :smiley: Any tips would be welcome.

Frost heave in winter will shift the whole thing. If you are going to mortar the bricks together, frost heave will just bust the and cracks the bricks/mortar.

You have two options and it doesn’t look like you chose either one:

  1. to brick and mortar a wall: Dig down and set a cement foundation below the frost line (24-36" depending on where you live). The foundation would support the brick and mortar wall. The foundation would prevent the ground from heaving up and busting up the wall.
  2. To set stones together, no mortar: Dig down anywhere from 12-24" and set down a gravel foundation. Atop the gravel, set down sand specifically desgined to support bricks/stones. The gravel will allow water to drain away, so that there is no water to freeze and heave the wall. The sand should be a type that drains water as well, yet can support and level the stones/bricks/whatever.
    If you have ever seen a half-assed crooked wall, fence, border, etc…the builder never addressed the frost heave issue.

If you’re going for a rustic-style dry stone wall, the issue of distortion and degradation may not be a problem (and may in fact be part of the attraction), although you may have to be prepared to maintain/rebuild it once or twice per decade.

Dry stone walling is quite an art though - there’s more to it than just stacking a bunch of rocks together. Personally though, I think it’s worth the extra work and maintenance, because the nooks and crannies in a wall of this kind can be planted up with succulents and creeping plants and/or left as a habitat for wildlife such as beetles, lizards etc…

Rock walls are my moms favorite walls. They seem to hold up quite well in Pennsylvania, there are walls still on my moms property over 50 years old made of just rock. The shifting gives a rustic look and nothing to be ashamed of as its the look. She does it like tetris, putting the pieces together, usually starting out with about ten times the amount of stone as she needs so she always has the right piece.
She also digs out the area where the wall will be and uses sand as the base, not sure why.

As Mangetout pointed out, the nooks and crannies make an excellent home for insects and crawling plants. But I guess this all depends on your taste in yard decor, none of this would fit right in my yard, but it fits perfect in other yards.

Since you live somewhere “South of Heaven” you’re probably in a pretty warm climate, so frost heave may not be much of a problem. If you’re only going up 6" or so you won’t need mortar, just stack carefully - there’s a real art to picking just the right rock for a particular spot.

I’ve done something similar in my back yard in Austin, TX and it has survived reasonably well for over 10 years.

It sounds like you live in the South. If so, then frost heave shouldn’t be a problem.

I’ve done the same thing around my house using the pavers that sprout out of the ground around here (the Texas Hill Country is basically built out of layers of limestone.) It might be nice to lay a 4-6" bed of mortar in the earth so that the stones don’t sink as the earth moves, but you can also just stack the rocks, trying to lock them together as you go along.

There are rock walls around here that were made, without mortar, a century or more ago by the farmers who first cleared the fields. Of course, they have probably been added to as more rocks surfaced.

El Zagna, apparently you have a faster dialup connection on your side of town!

I, too, am interested in doing a bit of field-stone work. Are there books about this stuff?

For a simple rock wall barrior around a garden I wouldn’t think digging down that low would be necessary. In New England and PA you can see centuries old rock walls that have somehow stayed together. They compensated for Frost heave by not using mortar, and by using varying gravity locks. Meaning they started out fat on the bottom and intertwined to a smaller top. Sometimes using filelr stones in the middle sometimes not.

For this project I’d think a simple dry stone build would suffice.

I bought this book last year and love it… it is very detailed.

Also google Andy Goldsworthy - I follow his work extensively and he is a master stone worker…with a twist :wink:

Okay, I was a bit anal with my description of how to build a wall, but this is because I have become overly suburbanized in South Jersey, and all I can picture is picture perfect walls around generic looking cookie cutter homes.

I grew up in Philly, PA and I have to admit that the older suburban PA landscape is much more charming. You probably can shoot for rustic and charming, and set the stones anyway you like.

Although, it is worth mentioning that if - on future projects - you do decide to use mortar outside, you might want to use a special mortar mix, not just any old cement.

I know what you meant Phil :slight_smile: I’ve recently gone from rocks, rocks everywhere in New England to having to BUY them if I need them here in az :EEK:

You can terrace the wall and use the rocks to build it. No mortar needed. you will dig back into the hill or slope excavating the top burden of soil/sand to pile behind you. You fill in behind the first row of boulders with earth and build it up, 2 or 3 terraces.

Need shovel and strong back that’s all!

That’s for sure. Back in Vermont, they say the main crop they raise is stones.

Also, the only way to plant corn in a rocky field is to use a shotgun. :slight_smile:

I built a three foot rock wall around a raised garden bed.

You’re right, it’s hard on the back, but the rewards are wonderful.

I used something called headstone, y’know, stones the size of your head.

I would suggest wider rocks on the bottom, I was told that’s how it was done in the olden days. You can’t tell by looking from the outside but my rock walls are actually 3 stones wide at the base.

I also had an oldtimer tell me to put small pieces of cotton rope in from one side of the wall to the other, obscured of course. Apparently this is important if winter weather is involved. However my walls are made with mortar not dry stacked.

It’s a very rewarding project, you’ll be delighted I predict.

How about a picture, when it’s done?

Good luck.

Other than what others have said here already, such as wider at the bottom, etc, there is one tactic.* Each rock should touch as many others as convenient. Ie, it rests on two or three rocks and presses against rocks on its left and right and offset behind it, while two or more rocks above it press on it. This is much better than just one under, one on each side, one behind, and one on top.

I believe that is why LostGoals’ mom gathers lots and lots of rocks before starting. It sounds as if she would work to avoid open space in her walls as much as possible.

Fool around with small rocks first. It was by making a prototype with small rocks that I became convinced that snugness and multi-touching are indeed desirable. The result feels stable and looks good.

*IANARWB (I am not a rock wall builder)

A little off topic. One of my first summer jobs was building rock walls for a guy. He had a house on the water.

He paid some one to blow-up his beach so there were piles and piles of slate coloured shale rock.

I built a series of rock retaining walls (no mortar) that were about 15 inches thick by about 3 feet high. Total linear length was around 500 feet!

It was insane, if the rocks were too big I had to break them with a sledge hammer. The dust was so crazy that when I took my jogging pants off (I always wore jogging pants back then) my legs were black from the dust! I imagine I took a couple of years off my lungs with that job!

But I have drove by that house a couple times in a boat and I must say those walls look spectacular!

MtM