Generally the height of a wall follows the profile of the ground. However, walls on undulating ground, especially significant walls such as estate boundaries, may be ‘evened up’ for better appearance.
To keep the wall stockproof all along its length, the wall height is increased in the hollows. This requires extra stone, so adding to the expense and time involved in wall building and repair. Some levelling of hummocks and filling of hollows may be worthwhile, depending on the situation, the availability of stone and other factors. For a new wall on undulating ground, a day’s work with a JCB may be a good investment to make the wall-building easier and cheaper. Preferably do any ground preparation some months before building the wall to allow time for the ground to settle.
When building an even-topped wall on undulating ground, great care must be taken to keep the wall width and batter constant. There are two ways of approaching this.
- The usual method is to keep a uniform batter from the wall top to ground level. This means that as the wall becomes higher, the width at the base increases. Careful measurement with line bars or use of a range of batter frames is necessary to make sure that the foundations are built to the correct base width for the corresponding height.
- An alternative approach, used in the Highlands of Scotland and elsewhere, is to build a platform called a scarcement, to create a level base from which the wall itself is measured and built. The scarcement is built with large foundation stones, ignoring strict grading in order to create a level top. The sides are vertical, with the width just slightly larger than the base width of the wall. Usually the wall is stepped in about 1″ (25mm) on both sides.
Walls built in this way are usually very sound, as the level scarcement allows good subsequent layering of the wall, and makes it easier to build a uniform and strong wall as the same dimensions are used throughout.
