I am not a huge fan of using battens to strengthen my bale walls. I much prefer to use welded wire mesh as I believe it not only provides a stronger hold, but also a superior “all around” structure for the walls. There are, however, specific cases where battens are needed and if you find yourself in one of those situations, this is the system I suggest you use.
One of the major problems with battens is that they sit proud of the surface of the bale wall so plastering around them is difficult. For starters, it’s all but impossible to get plaster behind the batten so to fully seal the wall in the scratch coat application. This leave the wall susceptible to air infiltration later on. Secondly, the battens, once covered with plaster, become a weak spot in the finish because the plaster is obviously thinner over the top of them and it also does not have as strong of a key as it does in the bales themselves. So how to fix this issue?
Use an angled batten. The battens that we used on a recent workshop build are shown here. Notice the profile is such that the triangular shape helps to pull the face of the batten flush with the face of the bale walls. This still leaves plenty of surface area to tie them to the walls (inside and out) and it also leaves a flat surface to be covered with roofing felt (all wood should be covered with felt if plaster is to go over it). It may take a little effort to work the battens into the bales so to get them flush with the wall, but it is well worth it and your plastering will be significantly easier as a result.
The last trick to an easy installation was given to me by John, a recent workshop participant. He created “the ultimate batten needle” which I have shown here as well. It is a simple wood jig designed to automatically space two needles to fit around the battens with ease. Plunge the batten needle through the bales (one needle on either side of the batten) and then have a friend on the outside attach the twine to both needles.
As you pull the needles back through the wall, the helper inserts their batten in between the twine and their side of the wall which is then pulled tight to the wall. Once you have the twines back on your side, tie them off in a tight miller’s knot. Simple and efficient. Thanks for the great jig John!!!