One thing is guaranteed in straw bale construction, no matter what building approach you take, you will need to make custom bales during the construction process. Bales need to be shortened at corners, windows, doors, and in gable ends along with several other areas of the home. Consider the window to the right. Obviously a series of rectangular bales would not fit against this window so adjustments would need to be made during construction.

If you plan to use a post and beam system that is encapsulated within the bale walls, then you will need to notch your bales so that they fit tightly against the posts. As discussed yesterday in the Framing Considerations section, the size of the posts is important in regards to minimizing the work involved with cutting your notches. In addition, the skill set needed to make the notches efficiently is one you will want to practice because all of the notching and resizing takes time to accomplish and the more skilled you are at each job, the better.


Needle and ThreadCutting a bale to a new, shorter length is not quite as simple as it sounds. Unlike working with wood, you cannot simply cut a bale to the length you need with a saw. Instead, you have to mark the bale where you want to cut it and then use a set of baling needles, like the one shown here, to tie new strings in place before you cut the old ones away. Be sure to insert your new strings as perpendicular to the bale as possible so that you keep a nice square end on the bale once the old strings are cut and the excess straw is removed. In addition, I suggest that you place your new strings on the inside of the existing strings. This allows you to make sure you don’t lose any ground in terms of the available depth for your post notches later on.

I have seen people use bale presses and cut the strings first, but I believe this is unnecessary. By using a high quality baling needle, you can create two custom bales from one original bale in a short amount of time once you have practiced the technique. The most important skill for retying bales is learning the miller’s knot.  This simple and strong knot is the only thing you need to keep the bales from falling apart. In fact, when you learn this knot, you will be able to retie bales even tighter than the baling machine that created them. This knot is simple, fast, and strong; however, it never fails that at every workshop I teach there is someone who does not figure out the knot with ease. This is fine, it is a new skill, so be patient with yourself as you learn it. Once you get it, like the participants who struggle with it at my workshops, you will be amazed that you ever wondered how it works. It’s that simple. Grab yourself some twine, settle in and then click here to watch a video of how to tie the knot. It’s worth practicing! If you prefer to read about the process with photographs and step by step instructions, please click here.


If you are building a straw bale house with a structure that is encased within the bales, then you will need to create notches in the bales like the one shown below in order to fit the them tightly around the framing members. Notching bales requires the use of a chainsaw and a can of spray paint to mark the notch locations. It is a simple yet important part of baling. When notching for posts, the tendency is to cut the bales almost exactly to the spray painted outline of the posts. This would make sense if working with wood, as a tight joint is important. Even though a tight joint is also valuable in straw to post unions, cutting the initial notch to fit a post location exactly will prove to be a mistake. The reason being that when the straw is removed from the notch, the bale will move to fill that void because it is under tension. That movement will cause the notch to shrink and the bale to no longer fit around the post in question. Instead, slightly over-cut the notch to accommodate for the movement in the bale. Knowing exactly how much to over cut will come with practice as that is a direct relation to the density of the bale. You will know after your first few attempts.

Deep NotchIt is important to be aware of your chainsaw blade at all times when cutting your notches. This is especially important for safety reasons and is also important because you do not want to cut the strings on the bale during the notching process. Some notches can be quite detailed and intricate and if you spend a lot of time working on a bale only to cut the twine by mistake, you may end up frustrated with the process. Any notch less than 4-5” deep can be made without too much concern for the location of the twine; however, a notch greater than 4-5” deep will require the extra step of tying the original twine out of the way on both sides of the bale (top and bottom) or retying a new piece of twine further back on the surface of the bale to replace the existing twine.

Like I mentioned above, these two aspects of straw bale construction are time consuming. Take the time to learn these steps well and have patience with your learning curve. What may seem redundant at first will be something well worth your effort once you start into your own build. Consider that in a typical 2100 square foot home, you can expect to retie 200 bales or more. Perhaps you don’t plan to build that big, but even half of that is a lot of retying!


Tomorrow we’ll take a look at the best methods of shaping your bales to get smooth and rounded edges etc…

Happy Baling!

Andrew Morrison