paul wheaton wrote:this video has a lot of good info:
Good stuff about:
- make the wall lean in
- set your rocks so the length of the rock goes into the middle of the wall rather than along the wall (3:33)
- don't have running joints (4:05)
- starting the build on top of the soil rather than starting below the soil. That can be okay.
- tie stones and cap stones
This bloke really knows what he's talking about, great video!
Having done a bit of dry stone walling, I can say that while it's easy to understand the basic principles it can be quite difficult to put them into practice. Especially if your stone happens to be of the awkward variety! I've always been told that the occasional deliberate mistake can be acceptible if there are no other options. You'll see in the video that there are some running joints but not too many. There are things you can do to mitigate some tracing or running joints.
For tracing, and as a general good practice for walling, you're trying to trap the stone with as much friction as possible. If the traced stone is firmly gripped by the stones next to, beneath and above it, then this is good. I would ensure that these stones were laid into the wall as it's important not to have another or multiple traced stones in the same location as this just compounds the weakness in that section.
For running joints I have been told that two stacked stones is fine but three is not. Again, you want to ensure that the neighbouring stones are well placed in order to mitigate any weakness from the running joint.
Another consideration is 'bridging'; this can happen when your coursing is uneven or if you're using smaller/larger than ideal stones. The stones you lay want to be sitting "two over one and one over two" much like in bricklaying so, if you end up doing one over three, you are bridging the middle stone and thereby establishing a weakness where the middle stone is not being trapped and held by the stones above it.
In terms of a walls foundations, I have always been told to dig them in unless we've been building on bedrock. If not, soil can be erroded from beneath the wall by wind and water allowing the bottom course of the wall to shift over time.
If your tie (or through) stones aren't long enough you can get at least some of the benefit by having the longest stones you can find sitting at least half way but ideally 2/3 to 3/4 of the way through and then alternating the side in which the end of the tie stone is hidden in the wall. As the stone that makes up the final 1/3 or 1/4 will be at a relatively shallow depth it's important that it is trapped by a longer stone or stones above it.