When building a dry stone wall, it is important to stand back and look at the work that has been completed. It is often difficult to see potential issues when you are working right on top of the wall. I have got into the habit of taking photographs at the end of each work day. Often these photographs reveal issues that even standing back cannot reveal.
If you look at the top image, the far left hand edge of the coping stones (the ones on the top of the wall) you can see that the wall trends downwards. This is more obvious if you look at the line of the wall directly underneath the coping stones.
The next image shows that this issue was corrected, but in the next section of the wall, the course of stones just underneath the coping stones now trends upwards. In the bottom image you can see that this issue has been again corrected. With a dry stone wall, it is relatively straightforward to strip off the coping stones and rebuild the wall and replace the coping stones.
So how do these errors occur? Simply put, by not religiously following the line that has been set up. On the other courses in the wall, you can deviate from the line of string knowing that this can be compensated for on subsequent courses. However, on the final course (the one before putting on the coping stones), you have no such leeway and the line of the string must be following very carefully.
