The best straw bales for building are those that are packed tightly into nice rectangles that allow for solid walls to be built.
The straw needs to be clean with no weeds or seeds as they may grow when wetted in the building process.
Straw bales are need to be very strong and robust to allow for the render to be applied and to be stacked many bales high. If the bales have been poorly made the strings can be loose and may slide of when being packed into the wall.
It also important that the straw has been stored inside and not outside in the rain. Rain and mould can weaken the bales and cause them to rot, which will ruin their structural integrity.
We have some great straw bales for sale currently, check them out!