How to build a dry stone wall

Building a dry stone wall is one of those jobs the difficulty of which could be defined as “easy” to “very complex”.

First of all, when we talk about dry stone walls we mean walls constructed without the use of any kind of mortar or concrete.

Like we already said, the difficulty level can vary a lot depending on the height of the wall, the terrain etc. It's certainly difficult to imagine your DIY neighbour building dry stone walls like those of Maiden Castle, North Yorkshire, or the well-known Mourne Wall in Northern Ireland. These were built with the aid of many people and above all a lot of skill.

A dry stone wall is in theory more difficult to construct than one built with the use of mortar. The reason for this is very simple: the mortar allows you to connect the stones and creates stability, even when the stones are badly laid out. Apart from this you'll need quite a bit of time and patience because in a day you'll not build much more than one cubic metre of stone, considering that you'll have to pick the stones carefully and if necessary reshape them so they'll fit in the spot where you want to lay them.

For a dry stone wall you absolutely have to work with patience, assuring that you put the right stone in the right place. The strength of the wall depends for a large part on your ability to fit the stones together as much as possible, like a kind of puzzle in which every piece has to be put in the right place.

dry stone wall in the countryside

If the wall that we want to construct is just a few dozen cm high (from about 20 to 50), anybody could probably do the job.

The higher your dry stone wall, the wider it'll have to be in order to guaranty stability; a 50cm high dry stone wall needs a minimum thickness of at least 30cm and if its thickness is equal to its height so much the better.

What we need in the first place are good stones and the more they are rectangular-shaped (meaning like bricks), the easier it will be to build our dry stone wall. Unfortunately, unless of course you buy already selected and prepared stones, nature will not often offer you perfect stones on a silver plate and you'll have to cut the stones at strategic places with a chisel or mallet so they'll fit in the best possible way.

With a small dry stone wall you could fence in your herb garden or give more emphasis to your flower beds or rock-garden plants.

We'd like to mention two types of dry stone walls, each with its own specific scope..

  1. The first type is the kind of wall we could define as “dividing” and which serves to border a piece of the garden. An indipendent wall like this nearly always has an “isosceles trapezoid” cross section, which guarantees its stability.
  2. The second type is the “earthbound” wall which has a more containing function and marks a different terrain level. Like we'll see in the second part of this article, this kind of dry stone wall is often used to create flower beds on a higher level than the surrounding land.

A dry stone wall as a border

First of all, we have to lay the “foundation” for our wall, meaning to excavate the terrain for about 15-20cm along its entire length and width. In this trench we lay the biggest and most massive stones which'll have the duty to give stability to the whole structure, even though only their upper part may remain visible.

How to use moulds for a dry stone wall.Like you'd already noticed from the pictures in this article, a bordering wall has the shape of a parallelepiped, the base of which is larger than the top. In order to create this shape you'll have to create two moulds (one for each end) with some pieces of wood and once positioned at each extremity of the trench you connect them with rope which will help you to build the wall according to the shape of the moulds themselves, like you can see on the picture on the right.

As an indication, the moulds would have a width of about one metre at the base and 30cm at the top, but obviously this can vary according the height of the wall; the mould we described could be used for walls of about a metre high or more, but in case you'd like to construct a lower wall (for whatever reason – let's say about 50cm high) you can easily do without the moulds and just use metal bars between which you tie some rope, just like with the moulds, which will help you to “go straight”.

An independent dry stone wall is basically composed of two stone “visible” walls in between of which you put smaller stones or the leftovers of the stones you cut in the process.

Angle of the dry stone wallTo raise the wall you obviously start from one of the ends, putting the stones alternating along the length and across in order to stagger the vertical joints. When placing the stones you simply follow the angle of the moulds so that the walls will lean inwards. Here at the left you can see a perfect example of one end, built according these criteria.

It goes without saying that building an independent dry stone wall requires at least two people, each working on their side and raising the various layers of stones. Once two or three layers have been laid, the internal part of the wall has to be filled with rubble and compressed as much as possible.

The construction of a dry stone wall has to proceed in layers, like with any other type of wall, until the final height is reached. As already said, try to make the stones fit as well as possible.

An important thing to note about positioning the stones: those of the upper layer must cover the joints of the lower layer and therefore tie them together in a way, like you can see in the picture..

Do not give in to the temptation to use dirt instead of mortar because that would be a mistake. Any precipitation will infiltrate the joints, wash away the dirt and so leave the stones “bare” (or better still “dry”) and therefore make them unstable.

Once the wall is finished, we must connect both faces of the wall with large, flat stones which will cover the top, protecting the structure against the rain. Above this closing layer you could eventually put other cover stones, which are often laid on their side or in a small slope (like you can see in the opening picture of this article) but which could also be placed alternating one vertical and one on its side.

A retaining dry stone wall

Building a dry stone wallA retaining dry stone wall differs from a boundary wall in the fact that it also serves to sustain an earth bank.

Like already said, a boundary dry stone wall can be made fairly easily, but impressive terrace structures like the ones that can be found in some regions are decisively beyond the skills of the passionate DIY

A garden dry stone wall can border an elevated herb garden or flowerbed, or emphasise and surround the trunk of a tree, its uses are many, but what truly matters is its rural aspect which can become stronger with time due to the presence of rock plants which tend to fill the cracks between the stones. We've seen previously how it's necessary to use a model to build a boundary wall which allows us to maintain the right inclination; also for a retaining wall we'll have to use a model which, however, in this case will be asymmetrical.

Retaining wallThe backside of a retaining dry stone wall has to be vertical in order to neutralise the lateral pressure of wet soil: the backside of the model therefore has to be perpendicular, while the front remains inclined towards the desired slope. As always, you'll have to use two models, one for each extremity of the wall.

If the wall is low, it can also be built with a sort of curve which sill “soften” its look. 

A retaining dry stone wall differs from a boundary wall in the fact that it also serves to sustain an earth bank. Like already said, a boundary dry stone wall can be made fairly easily, but impressive terrace structures like the ones that can be found in some regions are decisively beyond the skills of the passionate DIY.

If the wall is low, it can also be built with a sort of curve which sill “soften” its look.

For the rest, the construction of a retaining wall doesn't differ significantly from a boundary wall, with however one important remark: retaining walls are subject to pressure of the earth they have to contain and are therefore under more mechanical stress and are more susceptible to water infiltration which, in case it was poorly constructed, may compromise its stability .

The secret about how a retaining wall may resist time consists in the construction of a compensation “crate” between the wall itself and the terrain it is meant to contain. In substance, this “crate” consists of excavating a larger portion of earth behind the wall (or to place the wall more forward) in order to leave a cavity which will then be filled with rubble. This little “secret” makes that the weight of the earth behind is more uniformely distributed and doesn't put any direct pressure on the wall itself.

Here's a nice video which shows a few headlines about creating a retaining dry stone wall, but certainly not as tall as the one presented in the pictures: