Strengthen Your Walls
If you look at the picture above, and you know about my style of construction, you might think that when I talk about ways to strengthen your walls that I am going to talk about mesh. Although I am a big proponent of using mesh on my straw bale walls, that is not the topic of this conversation. Instead, I want you to focus on the boxed soffit above the bales. That is where a huge amount of strength is built into this wall. The soffit does not always need to be that big in order to get the strength because it's not the box itself that makes the wall strong. The key is in the location of that box, or more precisely, the elevation of the box.
By placing the bottom of the box LOWER than the height of the total amount of bales to be stack underneath it by 2" to 4", we make the space too small for the bale stack to comfortably fit. This means that the bales will have to be forced into position. This force provides a huge amount of compression on the walls and tightens things up tremendously.
For those of you who have been to one of my workshops, you have experienced this firsthand and can attest to the increase in wall strength this procedure provides (and the sweat it requires!). There are several ways to get the bales to fit into this small space. None of them is what I would consider to be easy, but that is actually the point. If it were easy, the walls would not be very tight. Hopefully that doesn't scare you away.
The fact of the matter is that we can minimize the difficulty, but as is true with so many aspects of home construction, this process will take some sweat to do properly. The photo to the left was taken in the Australia hands-on workshop and many of the participants did not believe we would be able to get the last bale course to fit into the space provided.
They thought it was too small for a full size course of bales to fit into. In the end, it did fit (after some persuasion) and the walls were incredibly tight as a result of the participant's hard work. I've outlined the best approach to achieve this large amount of compression with relative "ease" for you below.
Lay two ratchet straps over the top of the second to last course of bales. It is best to lay these over a piece of 1/2" plywood so that they will not bight into the bales when tightened. Make that plywood wide enough so that you can cut two handles into it that will stick out beyond the face of the bale wall when installed. The handles make the perfect spot for the straps to pass through. This gives you a way to get the plywood OUT after the wall is tight.
Place a small section of 2x6 on top of the second to last course of bales, on top of the plywood and in such a way that you can compress the entire bale with which you are working. By the way, we are working one bale at a time here...
Attach the ratchet straps firmly at the base of the wall. You may want to use large nails driven into the toe ups or, better yet, cut a piece of 1/2" plywood that can be attached to the toe ups and has a cut out for the strap hooks to attach to. A 2' x 2' piece should be sufficient.
Install a scissor jack (or two if that works better to push the bale down evenly) between the 2x6 and the bale stop (box soffit). If you cannot line the jack up underneath a framing member within the box, be sure to span across the soffit with a piece of 2x4 so that you don't attempt to tighten the wall against only the 1/2" layer of plywood of the box soffit. In fact, you may choose to "permanently" attach a piece of 2x4 to the top of the jack for the purpose of the wall tightening wide enough to span from outer frame to outer frame of the soffit (roughly 18").
Crank the jack down to compress the wall. As the wall tightens up, tighten up the straps to hold things in place. Go back and forth between using the jack to compress the walls and the straps to hold things in place. Don't try to use the straps to pull the wall down as you are better off using the jack.
Be careful to watch that the wall doesn't pop out of plane and fall over!
Once fully compressed and secured with the ratchet straps, remove the jack(s) and slide in the final bale for that area. It may take more muscle than you would expect, but that is okay...tighter is better!
Remove the tension from the straps and then pull the straps out of the wall.
Remove the top piece of plywood (this takes effort) and the strap anchor plywood pieces and move to the next bale.
Sound like a lot of work? Well, it kind of is. The good news is that every other aspect off the construction that you do moving forward from this point on will be easier as a result of the wall tightness. Stuffing, shaping, meshing, sewing, installing electrical and cabinets, plastering, and absolutely everything else will be easier.
It's like the old adage "spend a dime to save a dollar." For me, the extra work is more than worth it in the end and the quality of the overall job you will get as a result of this step is measurably better than working with soft or loose walls. If you have other ways of accomplishing the same level of wall compression (or better), I'd love to hear about them in the comments section below.
-Andrew Morrison