Watershot
In some regions wallers stress the need to lay stones at a slight angle in order to shed water and prevent it running into the wall. This avoids water gathering in the stonework, where it could disrupt the stonework by freezing and swelling. This technique, called watershot or weathershot, works best with small, flat stones. It is common in the Cotswolds and in the Lake District around Ambleside, Grasmere and Keswick. A mortared version of this style is known as ‘Lake District masonry’.
The stones only require a minimal tilt in order to shed water. If the stones are tilted too much they will themselves tend to slide.
Throughstones can be tricky to lay. Depending on the characteristics of the stone being used, you will need to decrease the tilt of the stones one or two layers before the throughs, to bring them up level enough for the throughs to be set securely. This is awkward to achieve with very regular stone.
Tracing
Whilst tracing is frowned upon for producing a weakened structure, it is a common practice in some areas.
The basalt walls of Skye and many granite walls in Aberdeenshire and elsewhere contain stones too large to fit length into the wall, even given the wider than normal width of these walls. With some stone types you can break large stones in half, and use the two parts placed length into the wall. However, stones such as basalt and granite are too dense to easily break, and the weight and size of the stones means that they sit solidly even when traced. They should be placed so that the width of the traced stone into the wall is greater than the height.
Tracing is also commonplace in the Cotswolds. Here the stone is oolitic limestone, which is amongst the lightest ‘walling’ stone. Tracing tends to cause poor bonding between the stones, resulting in walls which flake away, course by course. The individual stones are small, regular and light, which tends to increase the problem. To counteract this, many Cotswold wallers refer to ‘clapping’ the stones in place, which means that rather than being placed gently, they are virtually dropped into position. This places extra force on the stones below, firming up the structure and showing up any weak stones, which are then reset.
If it is necessary to trace stones in order to maintain a local style, then it becomes increasingly important that the other basic principles of construction are closely followed. Good line, batter and crossing of joints are especially important, so that all stones are well bound and forces evenly distributed. Avoid tracing very narrow stones, especially when placed low in the wall where they are a major cause of collapse. The style can be maintained while losing the worst traced stones.
Jumpers
Jumpers are tall face stones which in coursed walls ‘jump’ through two or three courses. They are used where you have a number of large stones, but not enough to form a complete course. The term does not strictly apply to random walls in which a layer necessarily contains neighbouring stones which are of different height. However, some random walls are built of fairly regular stones, in which the taller stones can be termed jumpers.
A jumper should be placed length into the wall to be secure. A jumper which is also traced will be inherently unstable. In extreme cases the face height of the jumper exceeds its length into the wall, being similar to, and sometimes referred to as ‘shiners’. These stones are particularly unstable. Generally they are not part of any regional style, but are just the occasional stone badly placed to save time. However, they do occur more routinely in the granite walls of Aberdeen and the basalt walls of Skye, where true shiners are common. Here the nature of the stone limits the way in which it can be used, and the style may represent the best use of what is available.
Green faces
Many wallers like to see gapping or rebuilding carried out using the stones with their weathered faces on the outside, a practice also called ‘green’, ‘mossy’ or ‘lichen’ side out. It’s argued that this not only makes the gapping or rebuilding blend with the old, but also helps accelerate the greening of stones placed with a fresh side out.
In practice greening is partly dependent on stone type and climate. In the wetter west, particularly in the uplands, the greening process is relatively quick, and even new walls lose their fresh look within a couple of years. However, placing the stone green side out may have some merit with more friable stone, such as Cotswold limestone and some laminates such as mudstone, which can become crumbly and disintegrate with age. Here the mosses and lichens provide a protective skin, reducing the effects of weathering. In general though, other principles of building are much more important, and green side out should not be used as an excuse for the incorrect placing of stone.
Pinnings
Pinnings or pins are wedge stones which are forced into gaps in the wall face, and are a traditional feature of walls in some areas, including much of Scotland. There are two main arguments in favour of pinning:
- It prevents snow from being blown into the heart of the wall, where it may melt and then re-freeze, slightly shifting the stones. This process of ‘freeze-thaw’ can seriously destabilise a wall over a period of years.
- Reducing the number of gaps in the face of a wall strengthens it by reducing the potential for settlement. Some pins may work loose under settlement and pop out, but others will be bound tighter, and it is these which will help extend the life of the wall.
In other areas pinnings are frowned upon, for the following reasons:
- You may disturb face stones or fillings when pushing in the pinnings.
- Pinnings, even if tapped with a hammer, may not be really secure, and often they are forced out as the wall settles or frost disturbs the face. Even with gentle tapping the pinnings often crack, allowing water to seep into them so they soon fragment.
- Pinnings are usually unnecessary as long as the face stones are properly placed and wedged from behind. Cracks and gaps are not a problem provided every stone sits tightly and the openings are too small for fillings to wash out. It is not essential to have every face stone snug against its neighbours if this might cause them to sit poorly.
Where pinnings are used, bear the following in mind:
- Use wedges and slivers, not rounded or square stones as these are more awkward to get tight, and more likely to pop out.
- Use one stone to one hole. Several small pins in a single hole are unlikely to stay tight.
- Preferably use freshly broken stone, as this tends to be rougher than weathered stone and will key better.
- Pins should be as long as possible to maximise stone to stone contact, but should not protrude beyond the face of the wall where they are likely to be knocked.
- Knock pinnings in with another stone or a wooden mallet as using a hammer tends to shatter them. Take care and don’t knock too hard as this can force the stones apart. Hart (1980) suggests that they should be pushed in by hand rather than hammered in.
Many wallers pin as they work along a layer, rather than pinning a complete section of wall. It must be remembered though that pins are a supplement to a wall’s strength, and should only be used to consolidate a stable structure. Resist the temptation to use pins to solve problems or to fill larger gaps which could be avoided with a little more patience.
