Dealing With the Top Bale Course

Written by Andrew Morrison

straw baling top courseExactly where the top course of bales will end depends directly on the size of the bales and the height of the wall. In addition, the way the frame is built will also have an effect. For example, if the floor/ceiling joists are sitting on top of the beam, then there will be a section of framing that will need to be notched out of the bales whereas if the floor/ceiling joists are hanging on the beam the bales will end tight to the floor/ceiling system without any notching for the beam.

It is likely that the bales will not fit perfectly into the wall assembly no matter how it is framed. This is simply part of the reality of construction. Even the best intentions of design can go astray in the field. If framed properly, a 9’eiling will provide a perfect fit for bales (of the right size) stacked tight to the floor/ceiling joists. For a 10′ ceiling I have found that turning the last course of bales on edge often creates a tight fit for the wall. The problem with this is the twine which ends up in the face of the bales. To plan ahead, I retie the bales so that when turned on edge the twine will not be on the face of the wall. This allows me to weed whack the bales as needed.

The cool thing about this system is that if the floor/ceiling joists are on top of the beams, the width of the bales turned on edge and placed against a 4x beam is almost exactly the same as the width of a bale laying flat and notched into the frame. So, it not only speeds up the stacking and strengthens the wall, but also fits perfectly! A little stuffing from the outside during meshing is all that is required. On a 9′ 6″ ceiling, you may need to simply add some flakes and stuff the top of the wall. This does not provide as strong a connection for the bales, so you may want to anchor the bales with a 2×4 between the frame as described in an earlier post.

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2 Responses

  1. At 2:22 PM, Anonymous said…

    Hi Andrew,

    I have a question about the detailing for a curved finish above windows. We plan to build a story and a half with straw bale on the main floor and double walls with blown-in cellulose on the second floor. The exterior walls will be 2×4 @ 24”O.C. stud walls (7 bale courses tall). Bales will be notched to finish with a flush exterior – much as you show on your DVD. I’m having trouble visualizing how to finish above the windows on the interior. For example, a 7’ window would have two 2×12’s as the lintel. Should one leave room to put a bale above the window opening, notched to fit around the top of this wide lintel? That would mean building a narrow box beam to sit in front of the lintel (narrow to allow curving of the bale before plastering – I know you don’t usually recommend curving the bale itself…). The window rough opening would then be sized at 14” (bale height) plus 1.5” (box beam) below the second floor joists. This leaves 12” on the back of the bale against the lintel that will not be plastered. Is this a problem? I noticed on the DVD that you did some windows with box beams and others with mesh stuffed with clay slip. Would the clay slip be the better approach here?

    The bales will end at the bottom of the second floor joists. The joists are 13” open web. We’ve been advised to insulate the between the joist space above the bales with blown-in insulation finished with rigid insulation to hold it in. What do you think about this method?


  2. Hi Andrew. I asked you about this in another topic, before we had gotten to this point in our construction. But now we’ve done it, so I would like to offer this alternative.

    My house is small, 25′ x 35′, with a simple shed roof and a cathedral ceiling. The roof is made with I-joists. This means that the two side walls have a slant.

    We had lengthy discussions about this, between ourselves (my finish-carpenter brother, who is the builder, and me, the unskilled labor), and with local straw-building experts.

    The solution we hit upon worked really well. First, we made a bale stop of 5/8-inch drywall nailed to the bottoms of the I-joists above the bale walls, abutting the beam. We laid the bale walls in a running bond as is customary. But when we got up to where things were getting tight (12-20″ of space left to fill), we made custom-shaped bales that were set *vertically* (as opposed to on edge as you described in this article). We used polyester strapping and a ratcheter to split our bales, and I got pretty good at splitting bales at a 7.5° angle to match the roof slope, then fine-tuning their shape with an electric chainsaw — which is our preferred notching tool too, by the way. Then my brother would do any beam and post notching that was needed. These vertical chunks fit so tightly that they had to be hammered in with the aid of a sheet of lumber tarp, which was pulled out afterwards, similar to your masonite suggestion under another topic.

    For the back wall, we made 7.5° wedges out of 2 x 4’s, nailed to the underside of the I-joists with the drywall under that, yielding a flat bale stop for that wall. The 8′ height of the wall didn’t allow for an even number of courses of horizontal bales, so the last course was vertical pieces hammered into place the same way, only in this case they were all the same height.

    I believe there are two advantages to this over putting the bales on edge as you described. First, there’s no need for “a little stuffing from the outside during meshing”. We decided that notching around the beam was a lot easier than stuffing later. Second, with the bale in the same orientation as “normal” bales in regard to the twine, the same amount of notching etc. is possible; in other words, you don’t have to worry about accidentally cutting a tie.

    The front wall, the tallest one, faces south and has a lot of glass for passive solar; that wall is frame construction, not bales.

    BTW most bale hammers end up with a name. Ours is Grabthar’s Hammer. You can google that.

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